sap db2 on db2 administration

DB2 Administration, Monitoring, Tuning

in SAP Environment

15 February, 20122

Agenda

Table space management

Table space concepts and administration Automatic Storage

Database administration

Log file management Backup / Restore / Recovery Table maintenance (runstats, reorg) DB2 Parameters Problem determination

Monitoring and performance tuning

Memory Management and STMM Monitoring Tools DB2 Parallelism

DB2 / SAP integration

SAP DB2 file system and table space layout SAP DB2 Cockpit ...

15 February, 20123

DB2 Table Space Management

15 February, 20124

Table Spaces Overview

DB2 table spaces store data and indexes

A table space consist of one or more containers. A container can be a

Directory

File

Device

There are two types of table spaces:

System managed space (SMS): The corresponding containers are directories. The operating system's file manager controls the storage space.

Database managed space (DMS): The corresponding containers are files or devices. The database manager controls the storage space.

15 February, 20125

Table Spaces And Containers

DB2 Instance

System

Database

SMS Table Space Tables Indexes Long data

Database objects Physical storage objects

Directory 1

DMS Table Space Tables Indexes Long data

Directory N

...

File 1

File N

...

Containers

Containers

15 February, 20126

Table Spaces Usage types

Depending on the usage type, the following table space categories can be distinguished:

Regular table space

Stores all permanent data

Uses 4 byte RIDs

Large table space

Always of type DMS.

V8: For example used to LONG VARCHAR and LOB data.

V9: Stores all permanent data. Uses 6 byte RIDs

System temporary table space

Stores temporary tables, i.e. work areas used by the database manager to perform operations such as sorts or joins.

15 February, 20127

Characteristics of DMS Table Spaces

Table space containers are

either pre-allocated files (DMS file containers)

or raw devices (DMS device containers)

Containers can be added, removed, or resized

The space allocation unit is an extent

Extents are striped across the containers of a table space in a round-robin fashion.

An extent consists of two or more pages

15 February, 20128

Characteristics of SMS Table Spaces

SMS table spaces use the file system manager of the operating system to manage the space where data is stored

Containers cannot be added after the table space has been created.

Table space capacity can be increased by enlarging underlying operating system file systems

The data in the table space is striped by extent across the containers

Database objects are stored in different files in the corresponding directories.

For example SQL*.DAT files store information about tables (the asterisk * is replaced by a unique set of digits that identifies the table)

Additional files may exist for a table (depending on data types, e.g. LONG fields and corresponding indexes that belong to the table).

15 February, 20129

Storage of Table and Index Data

Table data and corresponding indexes of a single table can be stored in different tablespaces:

Data can be stored in a DMS or SMS table space

Indexes can be stored separately from the data in a DMS or SMS table space.

Large data types (e.g. LONG VARCHAR) can be stored in a separate DMS LARGE table space.

15 February, 201210

Table Space Page Sizes

Table spaces can be created with the following page sizes:

4 KB

8 KB

16 KB

32 KB

A dedicated buffer pool is required for each page size which is used by the table spaces.

The default page size is 4 KB.

SAP uses uniform page size of 16K with Basis >= 6.40

Only one buffer pool required.

Increased table space size limits due to larger page size

15 February, 201211

Page Sizes And Table Space Limits (V8)

8KB

16KB

32KB

Page size

64GB

128GB

256GB

512GB

4KB

Table space size

Row ID (RID) 4 Bytes

4x109 Rows25516M

For tables in all table spaces (regular, temporary, DMS, SMS)

15 February, 201212

Page Sizes And Table Space Limits (V9)

8KB

16KB

32KB

Page size

2TB

4TB

8TB

16TB

4KB

Table space size

Row ID (RID) 6 Bytes

1.1x1012 Rows512M ~2K

For tables in LARGE table spaces (DMS only)Also all SYSTEM and USER temporary table spaces

15 February, 201213

Table Space Statements

15 February, 201214

Table Space Statements

The CREATE TABLESPACE statement defines a new table space

within the database, assigns containers to the table space, and records the table space definition and attributes in the catalog

The ALTER TABLESPACE statement is used to modify an existing

table space

Required privileges for the user who executed these statements are SYSCTRL or SYSADM authority

15 February, 201215

CREATE TABLESPACE DMS Example

CREATE LARGE TABLESPACE AKS#BTABPAGESIZE 16K MANAGED BY DATABASE USING(file'/db2/AKS/sapdata1/NODE0000/AKS#BTAB.container001'1000 M) EXTENTSIZE 2FILE SYSTEM CACHINGAUTORESIZE YES INCREASESIZE 200 M DROPPED TABLE RECOVERY OFF

15 February, 201216

CREATE TABLESPACE SMS Example

CREATE TEMPORARY TABLESPACE SYSTOOLSTMPSPACEIN DATABASE PARTITION GROUP IBMCATGROUP PAGESIZE 16K MANAGED BY SYSTEM USING ('/db2/V91/saptemp1/NODE0000/temp16/SYSTOOLSTMPSPACE.container000') EXTENTSIZE 2 PREFETCHSIZE AUTOMATIC BUFFERPOOL BP_STD_16K DROPPED TABLE RECOVERY OFF

15 February, 201217

Getting Information About Table Spaces

DB2 CLP commands:

db2 list tablespaces [show detail]

db2 list tablespace containers for [show detail]

DB2 snapshot:

db2 get snapshot for tablespaces on

SQL table functions:

Example: db2 "select PAGE_SIZE, EXTENT_SIZE, PREFETCH_SIZE from table(SNAPSHOT_TBS_CONT('sample',0) as o"

Command db2pd:

db2pd db tablespaces

15 February, 201218

Example LIST TABLESPACES SHOW DETAIL

Tablespaces for Current Database

Tablespace ID = 0Name = SYSCATSPACEType = Database managed spaceContents = Any dataState = 0x0000

Detailed explanation:Normal

Total pages = 166400Useable pages = 166398Used pages = 51408Free pages = 114990High water mark (pages) = 51408Page size (bytes) = 4096Extent size (pages) = 2Prefetch size (pages) = 2Number of containers = 1[]

15 February, 201219

Example LIST TABLESPACES SHOW DETAIL

[]Tablespace ID = 1Name = SYSTOOLSPACEType = System managed spaceContents = Any dataState = 0x0000

Detailed explanation:Normal

Total pages = 12761Useable pages = 12761Used pages = 12761Free pages = Not applicableHigh water mark (pages) = Not applicablePage size (bytes) = 4096Extent size (pages) = 32Prefetch size (pages) = 32Number of containers = 1

15 February, 201220

Example LIST TABLESPACE CONTAINERS

Output on Windows using DMS file containers:db2 list tablespace containers for 5

Tablespaces Containers for Tablespace 5

Container ID = 0

Name = c:\DB2\data.cont1

Type = Disk

Output on UNIX using device containers:db2 list tablespace containers for 5

Tablespaces Containers for Tablespace 5

Container ID = 0

Name = /dev/rdata1

Type = Disk

15 February, 201221

Changing the Size of a Table Space

15 February, 201222

Changing the Size of a Table Space

The ALTER TABLESPACE statement lets you

add a container to an existing DMS table space

or extend a container to increase its storage capacity

You can not ALTER a SMS table space instead you need to increase the size of the underlying file system

Data will be striped evenly across all of the table space containers until the individual containers fill up

Adding a container to a DMS table space which is smaller than existing containers may result in reduced performance

If some of the smaller containers become full, this may result in reduced I/O parallelism (e.g. during data prefetching).

15 February, 201223

Rebalancing

When new containers are added to a table space or existing containers are extended, a rebalance of the table space data may occur

The process of rebalancing is done in an attempt to keep data evenly distributed across all containers of the table space.

Access to the table space is not restricted during rebalancing but there can be a significant impact on performance

To avoid rebalancing you may

extend all existing containers by the same size

or add new containers in a new stripe set

15 February, 201224

Rebalancing (Contd)

A rebalancing is done asynchronously after the following ALTER TABLESPACE options:

ADD will result in forward rebalancing

DROP will result in reverse rebalancing

To avoid rebalancing choose the following ALTER TABLESPACE options:

RESIZE / EXTEND / REDUCE ALL CONTAINERS

BEGIN NEW STRIPE SET to create a new stripe set

15 February, 201225

ALTER TABLESPACE Examples

To add a new DMS container file to table space PSAPBTABD:ALTER TABLESPACE PSAPBTABD ADD (FILE '/db2/P01/sapdata5/PSAPBTABD.container005' 25000)

To extend all table space containers of table space ICP#STABD by10000 pages:ALTER TABLESPACE ICP#STABD EXTEND (ALL 10000)

To resize (e.g. shrink) all table space containers for table space Y9C#POOLI to a new size of 1000 Megabytes:ALTER TABLESPACE Y9C#POOLI RESIZE (ALL 1000)

To drop a DMS container from table space SYSCATSPACE:ALTER TABLESPACE SYSCATSPACE DROP (FILE '/db2/P01/sapdata5/SYSCATSPACE.container005')

15 February, 201226

ALTER TABLESPACE Examples (Contd)

To change the buffer pool for table space PSAPBTABD:ALTER TABLESPACE PSAPBTABD BUFFERPOOL SAPBP_32K

To change the prefetch size of table space Y9C#POOLI:ALTER TABLESPACE Y9C#POOLI PREFETCHSIZE AUTOMATIC

To turn off file system caching for table space ICP#STABD:ALTER TABLESPACE ICP#STABD NO FILE SYSTEM CACHING

To turn off dropped table recovery for table space APPL1:ALTER TABLESPACE APPL1 DROPPED TABLE RECOVERY OFF

15 February, 201227

Automatic Resizing Of DMS Table Spaces

DMS table spaces have a feature called "auto-resize (available with DB2 V8.2.2).

DB2 can automatically enlarge DMS table space for which the auto-resize attribute is activated.

SMS table spaces have similar capabilities for growing automatically but the term "auto-resize" is used exclusively for DMS

Two additional attributes, MAXSIZE and INCREASESIZE, are associated with auto-resize table spaces:

The MAXSIZE (Maximum Size) clause defines the maximum size for the table space.

The INCREASESIZE clause defines the amount of space which is automatically added when the table space becomes full.

15 February, 201228

How to enable Auto-resize

Creating a DMS tablespace and enabling the auto-resize feature:

CREATE TABLESPACE DMS1 MANAGED BY DATABASE USING (FILE '/db2data/DMS1' 10 M) AUTORESIZE YES

You can also enable or disable the auto-resize feature after a DMS table space has been created by using the ALTER TABLESPACE statement:

ALTER TABLESPACE NUC#BTABD AUTORESIZE YES

ALTER TABLESPACE NUC#BTABD AUTORESIZE NO

15 February, 201229

Auto-resize Monitoring (1/2)

Automatic resizing for DMS table spaces is displayed as part of the table space monitor snapshot output:

Tablespace name = NUC#USER1D

[]

Using automatic storage = No

Auto-resize enabled = Yes

File system caching = Yes

[]

Current tablespace size (bytes) = 10485760

Maximum tablespace size (bytes) = NONE

Increase size (bytes) = AUTOMATIC

Time of last successful resize = 05/18/2005 16:48:51.474454

Last resize attempt failed = No

15 February, 201230

Auto-resize Monitoring (2/2)

The db2pd command does also provide information about the automatic resizing of DMS tablespacesdb2pd db -tab[lespaces]

Tablespace Autoresize Statistics:Address Id AS AR Auto InitSize IncSize IIP MaxSize LastResize LRF0x00000004C3957960 0 No Yes No 0 -4096 No None 03/22/2006 16:19:51.434751 No0x00000004C395F960 2 No Yes No 0 -16384 No None None No0x00000004C3962920 3 No Yes No 0 -4096 No None None No0x00000004C3962FA0 4 No Yes No 0 -16384 No None None No0x00000004C396A0A0 5 No Yes No 0 -16384 No None 04/04/2006 07:42:36.268448 No0x00000004C396B1C0 6 No Yes No 0 -16384 No None None No0x00000004C396B840 7 No Yes No 0 -16384 No None 04/05/2006 15:41:02.263465 No

15 February, 201231

Use of Concurrent/Direct IO

Without file system caching DB2 always attempts to use concurrent I/O (CIO) wherever possible:

In cases where CIO is not supported (for example, if JFS is used), direct I/O (DIO) will be used instead.

NFS file systems usually do not support DIO/CIO (will result in warning messages in db2diag.log)

The settings for the table spaces can be retrieved with the GET SNAPSHOT FOR TABLESPACES command

Alternatively, use db2pd tab (search for column FSC)

15 February, 201232

Automatic Storage

15 February, 201233

Automatic Storage Overview

If automatic storage is enabled for a database the container management is completely handled by DB2.

Automatic storage databases have a set of one or more storage paths associated with them. Example:

CREATE DATABASE myDB ON /db2/ABC1, /db2/ABC2

If a table space is defined as "managed by automatic storage" DB2 performs the following tasks automatically:

Initial creation of table space containers in the given storage paths.

Extension of table space containers if required.

Adding table space containers if required.

15 February, 201234

Automatic Storage Overview (Contd)

A database can only be enabled for automatic storage when it is first created

You cannot enable automatic storage for a database that was not originally defined to use it

Similarly, you cannot disable automatic storage for a database that was originally designed to use it.

New storage paths can be added to the database later on. Example:

ALTER DATABASE myDB ADD STORAGE ON /db2/ABC3

15 February, 201235

Automatic Storage Database Path and Storage Path

The database path is the path where DB2 stores control files for the database. It is specified by the DBPATH ON clause in the CREATE DATABASE command.

The storage path is the path where DB2 creates automatic storage table space containers. It is specified by the ON clause. Multiple storage paths can be specified.

If the DBPATH ON clause is not specified, the first path listed in the ON clause indicates the database path (in addition to it being astorage path).

15 February, 201236

Automatic Storage Examples

CREATE DATABASE ABC ON /db2/ABC

Database is not automatic storage enabled (pre V8.2.2 default)

Attention: With V9 the database is automatic storage enabled per default

CREATE DATABASE ABC ON /db2/ABC1, /db2/ABC2

Database is automatic storage enabledDatabase Path: /db2/ABC1Storage Paths: /db2/ABC1, /db2/ABC2

CREATE DATABASE ABC ON /db2/ABC/sapdata1, /db2/ABC/sapdata2 DBPATH ON /db2/ABC

Database is automatic storage enabledDatabase Path: /db2/ABCStorage Path: /db2/ABC/sapdata1, /db2/ABC/sapdata2

15 February, 201237

Automatic Storage & SAPinst

Automatic storage is the default setup for all SAP NetWeaver 2004s (and higher) systems

15 February, 201238

Automatic Storage Table Spaces (1/3)

Automatic storage table spaces are an extension of the existing SMS and DMS table space types:

If the table space being created is a REGULAR or LARGE table space, it uses DMS file containers

If the table space being created is a TEMPORARY table space, it uses SMS directory containers

To create an automatic storage table space:

CREATE LARGE TABLESPACE myTS MANGED BY AUTOMATIC STORAGE

15 February, 201239


The names associated with the automatic storage containers have the following format:/

/

NODE0000/

/

T#######/

C#######.

EXT(ension) can be:CAT (system catalog),TMP (system temporary),UTM (user temporary),USR (user regular), LRG (user large)

Table space ID

Container ID

15 February, 201240


Example paths used for automatic storage in a NW04S system:

Tablespace Containers for Tablespace 0

Container ID = 0Name = /db2/SAT/sapdata1/db2sat/NODE0000/SAT/T0000000/C0000000.CATType = File


Container ID = 0Name = /db2/SAT/saptemp1/NODE0000/temp16/PSAPTEMP16.container000Type = Path


Container ID = 0Name = /db2/SAT/sapdata1/db2sat/NODE0000/SAT/T0000006/C0000000.USRType = File

Temporary table spaces are NOT using automatic storage in SAP environments

15 February, 201241

Automatic Storage Monitoring Storage Paths

A database snapshot includes the list of storage paths associated with the database:db2 get snapshot for db on

In addition you can use db2pd command:db2pd db sto[ragepaths]

Number of automatic storage paths = 2Automatic storage path = /db2/SXI/sapdata1Automatic storage path = /db2/SXI/sapdata2

Database Storage Paths:Number of Storage Paths 2

Address PathName0x237E0590 /db2/SXI/sapdata10x24260D90 /db2/SXI/sapdata2

15 February, 201242

DB2 Database Administration

15 February, 201243

DB2 Database Administration

Log file managementBackup / Restore / RecoveryTable maintenance (runstats, reorg)DB2 ParametersProblem determination

15 February, 201244

DB2 Logging Overview

Log Buffer Buffer Pool

db2agent

db2lo

gg

w

db2pcln

r

Online Active LogDatabase Files

synchronous write

on COMMIT/ ROLLBACK

every second

when log buffer is full

asynchronous write

chngpgs_thresholdis reached

SOFTMAX has been reached

No BP pages are available during insert/update

15 February, 201245

DB2 Logging Circular Logging

Default configuration after database creation

Not supported for production environments (no online backups possible no point-in-time recovery)

n

1

3

2Primary Logfiles

1

n

Secondary log files allocated if necessary / defined

15 February, 201246

Online archive:Contains information for committed and externalized transactionsStored in the active log directory

Offline archive: Archived fromactive log subdirectory to disk/ tape/ TSM

12

13

14

15

16

DB2 archives log file

(calls db2uext2 in V8.1)

Active: Containsinformation for non-committed or non-externalized transactions

DB2 Logging Archive Logging

db2uext2 located in $HOME/sqllib/adm (not provided by IBM)

15 February, 201247

DB2 Log File Management

Log Dir Mirror Log

DB2 Engine

Overflow Log

Failarch

Path

d

b

2

l

o

g

m

g

r

TSM DiskVendor

History

File

Tapedb2tapemgr

d

b

2

t

a

p

e

m

g

r

Beginning with DB2 Version 8.2 log file management is part of the DB2 engine

Supports disk, TSM, vendor library, user exit (db2uext2)

Log file location information is stored in history file

Configuration via DB configuration parameters

15 February, 201248

Logging Configuration Parameters (1/4)

Log archive method 1 (LOGARCHMETH1), log archive method 2 (LOGARCHMETH2)

These parameters cause the database manager to archive log files to a location that is not the active log path

If both of these parameters are specified, each log file is archived twice (e.g. to different media types)

The parameter value includes a media type and, in some cases, a target field. Use a colon (:) to separate the values

15 February, 201249

Valid values for LOGARCHMETH1and LOGARCHMETH2 are:

DISK:

Log files are archived to disk (e.g. log_archive directory)

TSM:

Tivoli Storage Manager is used for archiving.

VENDOR:

Vendor library is invoked. DB2 provides a vendor API for the log file management

USEREXIT

Program db2uext is invoked (not part of DB2 product)

LOGRETAIN

Log files are not archived automatically, i.e. inactive log files need to be archieved manually.

OFF


15 February, 201250


Log archive options 1 (LOGARCHOPT1), log archive options 2 (LOGARCHOPT2)

Specifies a string which is passed on to the TSM server or vendor APIs

Archive retry delay (ARCHRETRYDELAY)

Specifies the amount of time (in seconds) to wait between attempts to archive log files after the previous attempt fails

The default value is 20 seconds

Failover archive path (FAILARCHPATH)

Specifies an alternate directory for the archive log files if the log archive method specified fails

15 February, 201251


Log file size (LOGFILSIZ)

Size of log files (in 4 KB)

Number of primary log files (LOGPRIMARY)

Specifies the number of primary log files to be pre-allocated when starting the database

Number of secondary log files (LOGSECOND)

Specifies the number of secondary log files that are created andused for recovery log files (only as needed)

15 February, 201252

Logging Configuration Examples

To turn on direct archiving of log files to Tivoli Data Protector on AIX use the following command:

db2 update database cfg for QHA using LOGARCHMETH1 VENDOR:/usr/tivoli/tsm/tdp_r3/db264/libtdpdb264.adb2 update database cfg for QHA using LOGARCHOPT1 /db2/db2qha/tdpr3/vendor.env

To turn on archiving of log files to disk use the following command:

db2 update database cfg for TST using LOGARCHMETH1 DISK:/db2/TST/log_archive

15 February, 201253

LIST HISTORY COMMAND

The LIST HISTORY command lists entries in the recovery history file

To see entries regarding archive log operations the archived logs issue:db2 list history ARCHIVE LOG all for database

15 February, 201254

Closing Active Log File On Demand

A DB2 command allows users to close and archive the active log at any time

Allows users to acquire a complete set of log files up to the point in time at which the command is executed

Only useable on recoverable databases (i.e. database is defined to use archival logging)

Command:db2 archive log for database

15 February, 201255

Log Disk Full Vs. Log File Full

Two common problems that may occur regarding log space are:

SQL0964C: Transaction log full

Long running transactions are taking up all active log space of the database

Solution: force the oldest transaction (reported in db2diag.log) or increase the number of secondary log files

SQL0968C: Log disk full

DB2 cannot create new log files in the log directory because the file system is full

Usually caused by problems with the archiving of log files check the db2uext2, connection to TSM etc.

15 February, 201256

DB2 Backup

15 February, 201257

DB2 Backup Overview

The DB2 backup and restore utilities are built as part of the DB2 engine

Image(s) are logical format

Not file based

Provides more flexibility for restore, e.g. change disk layout on restore

Amount of resources used under complete control of the caller

The more resources allocated the faster the utilities will run

15 February, 201258

DB2 Backup Overview (Contd)

Backup Media available for DB2

Local devices, e.g. tape, disk, named pipe

Tivoli Storage Server (TSM)

XBSA compliant clients, e.g. Legato NetWorker

Vendor supplied DB2 library, e.g. Veritas NetBackup

DB2 Backup image contains table data as well as database configuration and history files

15 February, 201259

DB2 Backup Command Syntax (excerpt)

BACKUP DATABASE database-alias [USER username [USING password]]

[TABLESPACE (tblspace-name [ {,tblspace-name} ... ])] [ONLINE]

[INCREMENTAL [DELTA]]

[USE {TSM | XBSA} [OPEN num-sess SESSIONS] [OPTIONS {options-string | options-filename}] |

TO dir/dev [ {,dir/dev} ... ] |

LOAD lib-name [OPEN num-sess SESSIONS] [OPTIONS {options-string | options-filename}]]

[WITH num-buff BUFFERS] [BUFFER buffer-size] [PARALLELISM n]

[COMPRESS [COMPRLIB lib-name [EXCLUDE]] [COMPROPTS options-string]]

[UTIL_IMPACT_PRIORITY [priority]]

[{INCLUDE | EXCLUDE} LOGS]

15 February, 201260

DB2 Backup Command Examples

Example command for an offline backup of database SI1 using Legato NetWorker Module on Solaris with 2 sessions:BACKUP DB SI1 LOAD /usr/lib/libnsrdb2.so OPEN 2 SESSIONS

Example command for an online backup of database C11 to disk (directory c:\db2\backup):DB2 BACKUP DB C11 ONLINE TO c:\db2\backup

Example command for an online backup of two table spaces of database QH2 to Tivoli Storage Manager (TSM): BACKUP DB QH2 TABLESPACE (PSAPPOOLD, PSAPPOOLI) ONLINE USE TSM COMPRESS

15 February, 201261

DB2 History File

The DB2 history file contains a record of recovery and administrative events

Recovery events include backup, restore rollforward and archive log operations

Additional logged events include create, alter, drop, or rename table space, reorganize table, drop table, and load

Use the LIST HISTORY command to query the history file, for

example to see all backups for database QPT, issue:

db2 list history backup all for QPT

15 February, 201262

Op Obj Timestamp+Sequence Type Dev Earliest Log Current Log Backup ID-- --- ------------------ ---- --- ------------ ------------ --------------B D 20060110182712001 N O S0019095.LOG S0019100.LOG----------------------------------------------------------------------------Contains 7 tablespace(s):

00001 SYSCATSPACE00002 APPL100003 APPL00004 APPL200005 DFACT00006 APPL000007 SYSTOOLSPACE----------------------------------------------------------------------------

Comment: DB2 BACKUP QPT ONLINEStart Time: 20060110182712

End Time: 20060111013737Status: A

----------------------------------------------------------------------------EID: 32069 Location: /usr/lib/libnsrdb2.so

Op Obj Timestamp+Sequence Type Dev Earliest Log Current Log Backup ID-- --- ------------------ ---- --- ------------ ------------ --------------B D 20060110182712002 N O S0019095.LOG S0019100.LOG----------------------------------------------------------------------------Contains 7 tablespace(s):[]

LIST HISTORY BACKUP Example

Location: here Legato

Operation: BackupLog file sequence required for rollforward of ONLINE backup

15 February, 201263

DB2 Restore

15 February, 201264

DB2 Restore Command Syntax (excerpt)

RESTORE DATABASE source-database-alias { restore-options | CONTINUE | ABORT }

restore-options:

[USER username [USING password]]

[ TABLESPACE (tblspace-name [ {,tblspace-name} ... ]) [ONLINE] |

HISTORY FILE [ONLINE] | LOGS [ONLINE] | COMPRESSION LIBRARY [ONLINE]]

[USE {TSM | XBSA} [OPEN num-sess SESSIONS] [OPTIONS {options-string | options-filename}]

| FROM dir/dev [{,dir/dev} ... ]

| LOAD shared-lib [OPEN num-sess SESSIONS] [OPTIONS {options-string | options-filename}]]

[TAKEN AT date-time]

[TO target-directory] [INTO target-database-alias]

[LOGTARGET directory] [NEWLOGPATH directory]

[WITH num-buff BUFFERS] [BUFFER buffer-size]

[REPLACE HISTORY FILE]

[REPLACE EXISTING]

[REDIRECT]

[PARALLELISM n]

[COMPRLIB lib-name] [COMPROPTS options-string]

[WITHOUT ROLLING FORWARD] [WITHOUT PROMPTING]

15 February, 201265

DB2 Restore Command Example

Example command for a database restore of database SI1 using Legato NetWorker Module on AIX:

This command will replace the current SI1 database with the backup image taken at 05-05 2005 at 12:55:00

db2 "restore db si1 load /usr/lib/libnsrdb2.o open 2 sessions taken at 20050505125500 with 4 buffers buffer 2048 parallelism 2 replace existing without prompting"

Only if running older DB2 Version without self-tuning backup/ restore

15 February, 201266

Cross-platform Restoration

Supported by SAP for Heterogeneous System Copies

Windows 32-bit Windows 64-bit

HP-UX 32-bit

Solaris 32-bit

AIX 32-bit

HP-UX 64-bit

Solaris 64-bit

AIX 64-bit

Linux 32-bit Linux 64-bit

Big-endian Unix backup images are compatible

15 February, 201267

Database Copy Using Backup/Restore & Pipes

Database

RestoreBackup

Source Target

Database

1. Update .rhosts2. mkfifo 3. mkfifo 4. rsh "dd if= bs=8k" | dd of=5. db2 restore db from into 6. db2 backup db to

15 February, 201268

DB2 Recovery

15 February, 201269

DB2 Roll Forward Versus Restart Recovery

Two types of DB2 recovery:

Restart recovery (aka crash recovery)

Performed automatically during database restart (if DB parameter AUTORESTART is set to ON)

DB2 reruns all transactions that were performed previously but have not been written to disk

The DB2 log control file header contains the log sequence number, which must be used as the starting point of the recovery

Restore & roll forward recovery

Manually (using RESTORE and ROLLFORWARD commands or RECOVER)

15 February, 201270

DB2 Rollforward Command Syntax (excerpt)

ROLLFORWARD DATABASE database-alias


{[TO {isotime [USING LOCAL TIME] | END OF LOGS}] [AND COMPLETE]}

|

{COMPLETE | CANCEL | QUERY STATUS [USING LOCAL TIME]}

[TABLESPACE (tblspace-name [ {,tblspace-name} ... ]) [ONLINE]]

[OVERFLOW LOG PATH (log-directory)]

[RECOVER DROPPED TABLE dropped-table-id TO export-directory]

15 February, 201271

DB2 Rollforward Command Examples

To query the roll forward status of database A3M enter:db2 rollforward db A3M query status

To roll forward database B20 to end of logs (without using the db2uext2 to recover log files) and open the database afterwards,enter:db2 rollforward db B20 to end of logs and complete

To roll forward database BUD to 01-01-2006, 14:05 local time, enter:db2 rollforward db BUD to 2006-01-01-14.05.00.000000 using local time

The database will remain in rollforward pending state to open database issue db2 rollforward db BUD complete

15 February, 201272

Simplified Database Recovery RECOVER

The RECOVER DATABASE command combines the functionality of the RESTORE DATABASE and ROLLFORWARD DATABASE

commands

When you use this command, you specify the point-in-time to which you want the database recovered

You do not need to indicate which database backup image must be restored or which log files are required to reach the specified point-in-time

The RECOVER DATABASE command also supports recovery

operations to the end of the log files

15 February, 201273

RECOVER DATABASE Command Syntax (excerpt)

RECOVER DATABASE database-alias

[TO {isotime [USING LOCAL TIME | USING GMT TIME]

| END OF LOGS}

]


[USING HISTORY FILE (history-file)]

[OVERFLOW LOG PATH (log-directory)]

[COMPRLIB lib-name] [COMPROPTS options-string]

15 February, 201274

RECOVER DATABASE Command Examples

To use the latest backup image and rollforward to the end of logs using all default values:RECOVER DB XDM

To recover the database to a point-in-time, issue the following command:RECOVER DB PLN TO 2005-08-31-04:00:00

The most recent image that can be used will be restored, and logs applied until the PIT is reached

To recover a subset of partitions, issue:RECOVER DB J20 TO END OF LOGS ON DBPARTITIONNUMS(2 TO 4, 7, 9)

A point-in-time RECOVER cannot be done in this case, the recover must be done to end-of-logs

15 February, 201275

Monitoring Backup/Restore Operations

15 February, 201276

LIST UTILITIES Command

DB2 V8.2 introduces the LIST UTILITIES command

It can be used to monitor DB2 utilities like:

Backup

Restore

Crash recovery

Load

Rebalance

The SHOW DETAIL option of the LIST UTILITY command

provides information about the progress of the operation

Alternatively you can use the db2pd command, for example:db2pd uti[lities] [repeat 10]

15 February, 201277

LIST UTILITIES Command Example

15 February, 201278

DB2 9 Backup And Restore Enhancements

New table function to list all files in a database

Used to automate support of split mirror backup/recovery

Restartable Recovery

Re-issuing RECOVER command will pick up where it left off

Ability to change Point In Time in either direction

Rebuild partial database

Eliminate the need for FULL database restore

Ability to rebuild the database from set of table space backup images

Redirected Restore Script builder

Build a redirected restore script from a backup image:

...REDIRECT GENERATE SCRIPT file-name...

15 February, 201279

Table/Index Maintenance

15 February, 201280

Data Maintenance Process Overview

RUNSTATS REORGCHK REORG

RUNSTATS

FLUSH PACKAGECACHE

REBIND

Application Execution

YES

Reorganization needed?

NO

15 February, 201281

Overview of the REORGCHK Utility

REORGCHK is a data maintenance utility which uses the current database statistics to check if database objects need to be reorganized. Optionally it can also update database statistics.

It generates a report with multiple REORG indicators (e.g. F1,F2,F3) for tables and indexes.

Tables or indexes that require a REORG are marked with an asterisk.

C:\>db2 reorgchk current statistics on table user

Table statistics:

F1: 100 * OVERFLOW / CARD < 5F2: 100 * (Effective Space Utilization of Data Pages) > 70F3: 100 * (Required Pages / Total Pages) > 80

SCHEMA NAME CARD OV NP FP ACTBLK TSIZE F1 F2 F3 REORG----------------------------------------------------------------------------------------OLAF CL_SCHED - - - - - - - - - ---OLAF CLASS_LIST - - - - - - - - - ---OLAF DEPARTMENT 9 0 1 1 - 549 0 - 100 ---OLAF EMP_ACT 75 0 1 1 - 2850 0 - 100 ---OLAF EMP_PHOTO 12 0 1 1 - 2028 0 - 100 ---OLAF EMP_RESUME 8 0 1 1 - 984 0 - 100 ---OLAF EMPLOYEE 32 0 2 2 - 2784 0 68 100 -*-

15 February, 201282

REORGCHK Utility Examples

The following command checks table mytab based on the current table statistics:

REORGCHK CURRENT STATISTICS ON TABLE mytab

The following command updates the statistics and checks all tables created under the schema sapr3:

REORGCHK UPDATE STATISTICS ON SCHEMA sapr3

The following command updates the statistics and checks all tables:

REORGCHK UPDATE STATISTICS ON TABLE ALL

15 February, 201283

Overview of the RUNSTATS Utility

The RUNSTATS utility is used to collect statistics about the characteristics of a table and the associated indexes

Characteristics include number of records (cardinality), number of pages, average record length, and much more.

This information is used by the DB2 cost based optimizer to choose the optimal access plan

The decisions the optimizer makes are heavily influenced by statistical information about the size of the database tables and indexes

Therefore it is crucial to keep the database statistics up to date so that an efficient data access plan can be chosen!

15 February, 201284

RUNSTATS Syntax (excerpt)

RUNSTATS ON TABLE table-name [USE PROFILE | statistics-options]

statistics-options:

[table-object-options] [ALLOW {WRITE | READ} ACCESS]

[table-sampling-options] [profile-options] [UTIL_IMPACT_PRIORITY [priority]]

table-object-options:

[{FOR index-clause | [column-stats-clause] [AND index-clause]}]

table-sampling-options:

[TABLESAMPLE {BERNOULLI | SYSTEM} (numeric-literal)

[REPEATABLE (integer-literal)]]

profile-options:

[{SET PROFILE [NONE | ONLY] | UPDATE PROFILE [ONLY]}]

[UTIL_IMPACT_PRIORITY [priority]]

15 February, 201285

RUNSTATS Utility Examples

The following command collects statistics on the table db2user.employee; Read and write access is allowed while the statistics are being calculated:

RUNSTATS ON TABLE db2user.employee ALLOW WRITE ACCESS

The following command collects statistics on table db2user.employee and detailed statistics on all its indexes:

RUNSTATS ON TABLE db2user.employee AND DETAILED INDEXES ALL

15 February, 201286

Overview of the REORG Utility

The REORG utility reorganizes tables and indexes and eliminates fragmented or empty pages.

DB2 provides the option of performing the reorg online or offline

You may also reorganize a table using an index:

The order of RIDs in the index corresponds to the order of rows in the table after the reorg is completed.

This helps to minimize I/O operations when accessing data using that index.

Information about the table reorganization is available

in the database history file

in table snapshot output

15 February, 201287

Online Table Reorganization

Enhances database availability by allowing reorganization of tables while permitting read and write (online) table access

Reorg can be started, paused, and resumed.

Table is reorganized in a piece-wise fashion:

Vacate: Frees pages by moving

data to the back of the table

Fill: Fills the freed pages

VACATE PAGE RANGE: M O VE & C LE AN to m ake space

F ILL PAGE RANGE: M O V E & C LEAN to fill space

freespace

TIME

15 February, 201288

Index Reorganization

REORG INDEXES supports two different functions:

Rebuild: This is the default. Rebuilds the index data into unfragmented, physically contiguous pages.

Cleanup only: Indexes will not be rebuild. Removes committed pseudo deleted keys and pseudo empty pages.

Online index rebuild mechanism:

Shadow index is created during normal transaction processing

When index creation is complete, the old index is swapped out and the new index is made available

Sufficient temporary space needs to be available to build the new index

15 February, 201289

REORG Utility Examples

Reorg of table ATAB in-place while allowing write access db2 connect to

db2 reorg table sapr3.atab inplace allow write access

To start, pause, and resume an in-place reorg of the ATAB table use the following commands: db2 reorg table sapr3.atab inplace start

db2 reorg table sapr3.atab inplace pause

db2 reorg table sapr3.atab inplace allow read access notruncate table resume

Query database history file:

db2 list history reorg all for database

15 February, 201290

Automating Database Maintenance

DB2 allows the automation of certain database activities

BACKUP database

RUNSTATS on tables and indexes

REORG of tables and indexes

A Configure Automatic Maintenance wizard is available to specify

Maintenance objectives

Timeframe

Automatic Runstats is used for all new (7.00 and higher) SAP systems

Check SAP note # 860724 on how to enable older SAP releases for automatic runstats

15 February, 201291

Automating Database Maintenance Parameters

Enablement is controlled using the hierarchical set of automaticmaintenance database configuration parameters

AUTO_MAINT (parent of all other parameters)

AUTO_DB_BACKUP

AUTO_TBL_MAINT (parent of all table maintenance parameters)

AUTO_RUNSTATS

AUTO_STATSPROF

AUTO_PROFUPD

AUTO_REORG

Turn on all three values in blue to enable automatic

runstats

15 February, 201292

Automated Statistics Collection

Instead of the DBA triggering the statistic collection (deciding when to run RUNSTATS and which statistics to collect), there will be a background process which determines statistics that are out of date and collects them

Checking if RUNSTATS is needed takes place every two hours

There is no way for the DBA to change this at this time

Monitoring: Messages in the db2diag.log file indicate start / termination (success/failure) of automatic runstats execution

15 February, 201293

Automatic Statistics Collection db2diag.log

For databases with automatic runstats enabled you will see messages like the following in the db2diag.log:

2006-08-01-17.06.20.137341+120 I26461795A322 LEVEL: EventPID : 23400 TID : 2369 PROC : db2hmon 0INSTANCE: db2air NODE : 000FUNCTION: DB2 UDB, Automatic Table Maintenance, db2HmonEvalStats, probe:100START : Automatic Runstats: evaluation has started on database AIR

2006-08-01-17.18.31.757646+120 I26592803A377 LEVEL: EventPID : 23400 TID : 2682 PROC : db2hmon 0INSTANCE: db2air NODE : 000APPID : *LOCAL.db2air.060801151840FUNCTION: DB2 UDB, Automatic Table Maintenance, AtmTable::runstats, probe:500START : Automatic Runstats: runstats has started on table "SAPR3 "."DFKK_TRIGGER_PAY"

2006-08-01-17.18.33.704169+120 I26593181A388 LEVEL: EventPID : 23400 TID : 2682 PROC : db2hmon 0INSTANCE: db2air NODE : 000APPID : *LOCAL.db2air.060801151840FUNCTION: DB2 UDB, Automatic Table Maintenance, AtmTable::runstats, probe:900STOP : Automatic Runstats: runstats completed successfully on table "SAPR3 "."DFKK_TRIGGER_PAY"

15 February, 201294

Checking Database Statistics

To check if database statistics are up to date you can query theSTATS_TIME from the SYSCAT.TABLES system catalog view

Example:db2 "select substr(tabname,1,20), stats_timefrom syscat.tables where tabname = MYTAB"

To check entries in db2diag.log the db2diag tool can be used.

Example:

db2diag gi "function:=runstats,stop:=mytab"

15 February, 201295

DB2 Parameters

15 February, 201296

DB2 Environment

Configure the DB2 environment via:

DB2 Profile Registry

Operating System Environment Variables

DB2 Database Manager Configuration Parameters

DB2 Database Configuration Parameters

Server machine

DB2 registry

New features, platform

dependent parameters,

special optimizations

Database manager

configuration file

DBM CFG

Database configuration file

DB CFG

Database

Instance

OS environment variables

15 February, 201297

DB2 Profile Registry Variables

Use the db2set command to update registry variables

Parameters can be set globally or for a specific instance:

To set a parameter for current instance:

db2set parameter=value

To set a parameter for a specific instance:

db2set parameter=value -i instance_name

To set a parameter at the global level:

db2set parameter=value -g

Changes take effect after the instance has been restarted.

15 February, 201298

Registry Variables for SAP Installations

For SAP installations a special aggregate registry variable has been designed:db2set DB2_WORKLOAD=SAP

To see the values that are included in DB2_WORKLOAD=SAP run db2set gd DB2_WORKLOAD=SAP

15 February, 201299

Aggregate Registry Variables Example V8.2

[i] DB2_WORKLOAD=SAP[i] DB2_MDC_ROLLOUT=YES [DB2_WORKLOAD][i] DB2_SKIPINSERTED=YES [DB2_WORKLOAD][i] DB2_VIEW_REOPT_VALUES=YES [DB2_WORKLOAD][i] DB2_OBJECT_TABLE_ENTRIES=65532 [DB2_WORKLOAD][i] DB2_OPTPROFILE=YES [DB2_WORKLOAD][i] DB2_IMPLICIT_UNICODE=YES [DB2_WORKLOAD][i] DB2_INLIST_TO_NLJN=YES [DB2_WORKLOAD][i] DB2_MINIMIZE_LISTPREFETCH=YES [DB2_WORKLOAD][i] DB2_UPDATE_PART_KEY=YES [DB2_WORKLOAD][i] DB2_REDUCED_OPTIMIZATION=4,UNIQUEINDEX,JOIN [0][i] DB2NOTIFYVERBOSE=YES [DB2_WORKLOAD][i] DB2_INTERESTING_KEYS=YES [DB2_WORKLOAD][i] DB2_EVALUNCOMMITTED=YES_DEFERISCANFETCH [DB2_WORKLOAD][i] DB2_ANTIJOIN=EXTEND [DB2_WORKLOAD][i] DB2_SKIPDELETED=NO [0][i] DB2MEMMAXFREE=2000000 [DB2_WORKLOAD][i] DB2_RR_TO_RS=YES [DB2_WORKLOAD][i] DB2_FORCE_FCM_BP=YES [DB2_WORKLOAD]

These values have been overwritten (signified by the [O])

15 February, 2012100

DB2 Configuration Parameters

Two groups of parameters:

Database Manager Configuration parameters (DBM CFG)

Database Configuration parameters (DB CFG)

Types of parameters:

Configurable (changes take effect after restart)

Configurable Online (no restart required)

Configurable Automatic (self tuning)

Informational


How To Change The Parameters?

Parameters can be viewed/modified using the following CLP commands:

Database Manager Configuration commands:

GET DATABASE MANAGER CONFIGURATION(or: GET DBM CFG)

UPDATE DATABASE MANAGER CONFIGURATION(or: UPDATE DBM CFG)

Database Configuration commands:

GET DATABASE CONFIGURATION FOR (or: GET DB CFG FOR )

UPDATE DATABASE CONFIGURATION FOR (or: UPDATE DB CFG FOR )


Database Manager Configuration Sample OutputDatabase Manager Configuration

Node type = Enterprise Server Edition with local and remote clients...Diagnostic error capture level (DIAGLEVEL) = 3Notify Level (NOTIFYLEVEL) = 3Diagnostic data directory path (DIAGPATH) =...Default database monitor switches

Buffer pool (DFT_MON_BUFPOOL) = ONLock (DFT_MON_LOCK) = ONSort (DFT_MON_SORT) = ON

...Database monitor heap size (4KB) (MON_HEAP_SZ) = 66Java Virtual Machine heap size (4KB) (JAVA_HEAP_SZ) = 512Audit buffer size (4KB) (AUDIT_BUF_SZ) = 0Size of instance shared memory (4KB) (INSTANCE_MEMORY) = AUTOMATIC...Maximum query degree of parallelism (MAX_QUERYDEGREE) = ANYEnable intra-partition parallelism (INTRA_PARALLEL) = YES...No. of int. communication buffers(4KB)(FCM_NUM_BUFFERS) = AUTOMATICNo. of int. communication channels (FCM_NUM_CHANNELS) = AUTOMATIC...


Some Important DBM CFG Parameters

DIAGLEVEL (Diagnostic Error Capture Level)

DIAGPATH (Diagnostic Data Directory Path)

Monitor Switches (DFT_MON_SORT, )

NUM_POOLAGENTS (Size of the DB2 agent pool)

SVCENAME (TCP/IP Service Name)

INTRA_PARALLEL (Enables Intra-Partition Parallelism)


Database Configuration Sample OutputDatabase Configuration for Database sample

Database configuration release level = 0x0b00Database release level = 0x0b00...Self tuning memory (SELF_TUNING_MEM) = ONSize of database shared memory (4KB) (DATABASE_MEMORY) = AUTOMATICMax storage for lock list (4KB) (LOCKLIST) = 50Percent. of lock lists per application (MAXLOCKS) = 22Package cache size (4KB) (PCKCACHESZ) = (MAXAPPLS*8)Sort heap thres for shared sorts (4KB) (SHEAPTHRES_SHR) = 5000Sort list heap (4KB) (SORTHEAP) = 256...Changed pages threshold (CHNGPGS_THRESH) = 60Number of asynchronous page cleaners (NUM_IOCLEANERS) = AUTOMATICNumber of I/O servers (NUM_IOSERVERS) = AUTOMATICIndex sort flag (INDEXSORT) = YESSequential detect flag (SEQDETECT) = YESDefault prefetch size (pages) (DFT_PREFETCH_SZ) = AUTOMATIC...


Some Important DB CFG Parameters

BUFFPAGE (Buffer Pool Size)

LOCKLIST (Size limit for Lock List)

SORTHEAP (Size limit for one active sort operation)

UTIL_HEAP_SZ (Utilities Heap Size)

NUM_IOCLEANERS (Number of Page Cleaners)

NUM_IOSERVER (Number of I/O Servers - Prefetchers)

LOGFILSIZ (Log File Size)

LOGPRIMARY (Number of Primary Log Files)

LOGSECOND (Number of Secondary Log Files)


Configuration Commands Enhancements

GET DBM CFG SHOW DETAIL

Displays detailed information showing the current value of database manager configuration parameters as well as the value of the parameters the next time you start the instance

GET DB CFG FOR SHOW DETAIL

Displays detailed information showing the current value of database configuration parameters as well as the value of the parameters the next time you activate the database


GET DB CFG SHOW DETAIL Example Output

Database Configuration for Database

Description Parameter Current Value Delayed Value-----------------------------------------------------------------------------------------------------------

Database configuration release level = 0x0a00Database release level = 0x0a00

Database territory = en_USDatabase code page = 1208Database code set = UTF-8Database country/region code = 1Database collating sequence = IDENTITY_16BIT IDENTITY_16BITAlternate collating sequence (ALT_COLLATE) =Database page size = 4096 4096

Dynamic SQL Query management (DYN_QUERY_MGMT) = DISABLE DISABLE

Discovery support for this database (DISCOVER_DB) = ENABLE ENABLE

Default query optimization class (DFT_QUERYOPT) = 5 5Degree of parallelism (DFT_DEGREE) = 1 1Continue upon arithmetic exceptions (DFT_SQLMATHWARN) = NO NODefault refresh age (DFT_REFRESH_AGE) = 0 0Default maintained table types for opt (DFT_MTTB_TYPES) = SYSTEM SYSTEMNumber of frequent values retained (NUM_FREQVALUES) = 10 10Number of quantiles retained (NUM_QUANTILES) = 20 20

Backup pending = NO

[]


DB2 Configuration Parameters & SAP

As a starting point to tune your SAP DB2 database follow the SAPrecommendations.

SAP notes with DB2 standard parameter settings:

584952 DB2 UDB ESE V8.1 and V8.2

899322 DB2 9.1 Standard Parameter Settings




Problem Determination


Problem Source Identification

Essential diagnostic information to identify the source of a problem:

db2diag.log

db2level

DB2 configuration (instance, database, registry)

Other possible information needed SAP/IBM support:

db2nodes.cfg, trap/ dump files, stack files, core files, db2dart, DB2 Trace

Environment (set or env)

Use the db2support tool to collect the data


First-failure Data Capture (FFDC)

First-failure data capture (FFDC) information is the set of diagnosticinformation that DB2 captures automatically when errors occur.

Configuration parameters:

The DIAGPATH dbm parameter specifies the path to the FFDC storage directory

The DIAGLEVEL and NOTIFYLEVEL parameters control the detail of information you receive in the log files.

The information captured by FFDC includes the following:

db2diag.log and administration notification log

Dump files and trap files

Core files (on UNIX)


DB2DIAG.LOG

The first and most important source for problem analysis!

Contains records about errors, warnings and informational records.

Typical locations of DB2DIAG.LOG (values of DIAGPATH)

Standard on UNIX: $HOME/sqllib/db2dump

Standard SAP Installation on UNIX: /db2//db2dump

Standard on Windows: \\


DB2DIAG.LOG DIAGLEVEL

DIAGLEVEL

0 No logging

1 Severe errors

2 Severe and non-severe errors

3 Severe and non-severe errors plus warnings

4 Severe and non-severe errors, warnings and Info

Default is 3 and acceptable for most of the time

Level 4 generates a lot of information - only useful in special situations (e.g. installation, migration)


DB2DIAG.LOG Examples (1/3)

2004-07-14-15.45.13.569918+120 I1A895 LEVEL: EventPID : 20940 TID : 1 PROC : db2agent (instance) 0INSTANCE: db2xdm NODE : 000 DB : XDMAPPHDL : 0-474 APPID: *LOCAL.db2xdm.040714163353FUNCTION: DB2 UDB, RAS/PD component, _pdlogInt, probe:120START : New db2diag.log fileDATA #1 : Build Level, 144 bytesInstance "db2xdm" uses "64" bits and DB2 code release "SQL08020"with level identifier "03010106".Informational tokens are "DB2 v8.1.0.64", "s040704", "U498351", FixPak "7".DATA #2 : System Info, 1328 bytesSystem: SunOS us0014 5.8 Generic_108528-11 sun4uCPU: total:4 online:4Physical Memory: total:2048 free:644Virtual Memory: total:10229 free:7466Swap Memory: total:8181 free:6822Information in this record is only valid at the time when this file wascreated (see this record's time stamp).

Timestamp & time zone

Severity level

DB2 level information for started instance

Detailed Information: OS level, DB2 level, available memory, number of CPUs



2004-07-14-16.16.46.431884+120 I53029A379 LEVEL: EventPID : 23827 TID : 1 PROC : db2agent (instance) 0INSTANCE: db2xdm NODE : 000APPHDL : 0-8 APPID: *LOCAL.db2xdm.040714141645FUNCTION: DB2 UDB, config/install, sqlfLogUpdateCfgParam, probe:20CHANGE : CFG DB XDM: "Util_heap_sz" From: "5000" To: "131072"

Changes to configuration files documented in db2diag.log

2004-07-14-19.02.54.893205+120 E123020A589 LEVEL: ErrorPID : 7207 TID : 1 PROC : db2agent (XDM) 0INSTANCE: db2xdm NODE : 000 DB : XDMAPPHDL : 0-9 APPID: *LOCAL.db2xdm.040714165506FUNCTION: DB2 UDB, buffer pool services, sqlbAllocateExtent, probe:830MESSAGE : ADM6044E The DMS table space "PSAPLOADI" (ID "20") is full.

Additional space can be added to the table space by either adding new containers or extending existing ones using the ALTER TABLESPACE SQL statement.

Severity level Error



2006-04-21-15.26.11.839221+120 E6835E555 LEVEL: Error (OS)PID : 6259 TID : 182968115104PROC : db2med.6158.0 0INSTANCE: db2a3m NODE : 000FUNCTION: DB2 UDB, oper system services, sqloLoadModule, probe:190CALLED : OS, -, dlopen OSERR: EINTR (4)DATA #1 : Library name or path, 21 bytes/usr/lib/libnsrdb2.soDATA #2 : shared library load flags, PD_TYPE_LOAD_FLAGS, 4 bytes0DATA #3 : String, 80 bytes/usr/lib/libnsrdb2.so: cannot open shared object file: No such file or directory

OS error

Unique record ID

Formatted OS error code

Called OS function


Administration Notification Log

In addition to the db2diag.log an administration notification log (aka notify log) is available:

Focus on administrative events (db2diag.log is intended for problem determination). Intended for use by database and system administrators.

Notification messages also provide additional information to supplement the SQLCODE.

The notification log is available on UNIX & Linux. On Windows it is part of the Windows Event Log

The type of event and the level of detail of the information gathered are determined by the NOTIFYLEVEL (DBM parameter)

Location defined by DIAGPATH configuration parameter

File name is .nfy (for example db2sxi.nfy)

Log messages are NLS enabled (i.e. printed in the locale of the database) while the db2diag.log is always in English


DB2 Notify Log Examples With Errors

2005-06-08-11.46.52.310415 Instance:db2sxi Node:000PID:23941(db2wdog 0 0) TID:332701696 Appid:noneoper system services sqloRunInstance Probe:490

ADM0503C An unexpected internal processing error has occurred. ALL DB2PROCESSES ASSOCIATED WITH THIS INSTANCE HAVE BEEN SHUTDOWN. Diagnosticinformation has been recorded. Contact IBM Support for further assistance.

2005-03-24-11.34.29.242569 Instance:db2sxi Node:000PID:89198(db2agent (SXI )) Appid:*LOCAL.db2inst1.020205091435recovery manager sqlpresr Probe:370 Database:SXIADM1531E Crash recovery has completed successfully.


Diagnostic Information for IBM customer support

In addition to the db2diag.log (and the administration notification) you may find the following files in the DIAGPATH, for example:

Trap files: Function call stack, signals, exceptions.

Core files: Memory image of terminated processes.

Dump files: Additional information (control blocks etc)

DB2 event log: Circular log of infrastructure-level events occurring in the database manager.


A Typical DB2 DIAGPATH

-rw-r--r-- 1 db2qpt sysadm 747988 May 6 2005 xbsa.log

-rw-rw-rw- 1 db2qpt sysadm 4124675 Jun 16 2005 db2diag.log_2005-06-16-10.59.37

-rw-r----- 1 db2qpt sysadm 6291376 Jul 18 2005 db2eventlog.000.crash

-rw-r----- 1 db2qpt sysadm 6291376 Feb 12 15:57 db2eventlog.000

drwxr-xr-x 2 db2qpt sysadm 4096 Feb 12 16:58 DART0000

-rw-r--r-- 1 db2qpt sysadm 2731 Feb 12 17:04 t22378.000








drwxr-x--- 2 root sysadm 4096 Mar 1 19:37 c16591.000

-rw-r--r-- 1 root sysadm 14699 Mar 1 19:37 t16591.000

drw-rw-rw- 1 db2qpt sysadm 19514552 May 2 13:27 db2qpt.nfy

-rw-r--r-- 1 db2qpt sysadm 9262825 May 2 15:29 UserExit.log

-rw-rw-rw- 1 db2qpt sysadm 305440156 May 2 15:29 db2diag.log

Trap files

Core file

Notify log

Event log

db2dart files


Collect System Diagnostic Information db2support

The db2support utility is designed to automatically collect all DB2 and system diagnostic information available

The utility will collect for example:

The db2diag.log, all trap files, lock list files, dump files, buffer pool and table space control files, database and database manager configuration, system information

Collecting most of the information required to debug a problem:db2support -d -c

Information is stored in a compressed ZIP archive db2support.zip


DB2 Monitoring and Performance Tuning


DB2 Monitoring and Performance Tuning

Memory management

Self Tuning Memory Manager (STMM)

Monitoring Tools (e.g. snapshots, db2pd)

DB2 Parallelism (intra- and inter partition parallelism)


DB2 Memory

Database Shared Memory

Visible to all processes

Some restrictions apply for older DB2 releases (e.g. number of shared memory segments is limited on 32 bit plattforms)

Private Memory

Visible only to the process that allocates it


Agent/ Application Shared MemoryAgent/ Application Shared Memory

Agent Private MemoryAgent Private Memory

Application Global MemoryApplication Global Memory

Database Global MemoryDatabase Global Memory

DB2 Memory Areas

Database Manager Shared Memory

Database Global Memory

Application Global Memory

Agent Private Memory

Agent/ Application Shared Memory

Allocated when database manager is started.Contains monitor heap, FCM buffers, etc.

Allocated when database is activated. Contains buffer pools, locklist, shared sort area, package cache, etc.

Allocated when an application connects to the databaseUsed e.g. for communication between agents that work on the same SQL statement (if intra_parallel is enabled).

Allocated when an agent is createdUsed e.g. for private sort heap

Allocated e.g. when a client issues a connect requestUsed for communication between an agent and an application


Consumers of Database Global Memory

Database Global Memory contains the following areas which can be adjusted online:

Buffer pools (most important tuning area)

Sort heap

Lock list

Package cache, catalog cache

Utility Heap

Database heap (e.g. log buffers)

Size of Database Global Memory is defined by parameter database_memory.

If database_memory is set to computed DB2 computes an appropriate value when the database is activated.


Memory Tuning in DB2 9 STMM

DB2 9 introduces the Self Tuning Memory Manager (STMM):

STMM senses the underlying workload and adjusts the size of the most important memory areas accordingly

Can adapt quickly to workload shifts that require memory redistribution

Adapts tuning frequency based on workload

Database memory areas that can be dynamically adjusted by STMM:

Buffer pools

Sort heap

Lock list

Package cache

Total size of database memory


STMM Activating Self Tuning Memory

1. Update your database configuration for all consumers:

db2 update db cfg for using

LOCKLIST AUTOMATIC

MAXLOCKS AUTOMATIC

PCKCACHESZ AUTOMATIC

SORTHEAP AUTOMATIC

SHEAPTHRES_SHR AUTOMATIC

2. Enable your bufferpools for STMM tuning:

db2 alter bufferpool size AUTOMATIC

3. Set DATABASE_MEMORY to automatic:

db2 update db cfg for using DATABASE_MEMORY AUTOMATIC

4. Switch on STMM:

db2 update db cfg for using SELF_TUNING_MEM ON


Buffer Pool - Overview

A buffer pool is a storage area into which database pages (containing table rows or index entries) are temporarily read (and optionally changed).

The purpose of the buffer pool is to improve database system performance (data can be accessed faster from memory than from disk).

Multiple buffer pools can be configured for a database, e.g. to ensure that frequently accessed small tables are not swapped outby large tables.

Buffer pools are assigned to table spaces, i.e. different table spaces may use different buffer pools.


Buffer Pool Allocation Guidelines

Buffer pool size specification

Too small buffer pools may result in excessive disk I/O.

Oversized buffer pools may result in paging.

How to specify the buffer pool size:

ALTER BUFFERPOOL name SIZE

Let STMM figure out the optimal size of bufferpools depending on current workload.

Guidelines

The buffer pool should use at least 1/2 of the available memory

A well tuned system should have a buffer pool hit ratio larger 96 percent


Database Partition 1

Sort Memory

Allocation of sort memory:

INTRA_PARALLEL=OFF

Sort memory is agent private memory.

SHEAPTHRES is a soft limit for total sort memory of each database partition.

INTRA_PARALLEL=ON

Sort memory is shared memory.

Sort memory of size SHEAPTHRES_SHR is a hard limit for total sort memory.

SHEAPTHRES_SHR can be defined per partition.

Recommendations for initial sizing (SORTHEAP,SHEAPTHRES) are described in SAP notes 584952 (DB2 V8) and 899322 (DB2 9):

SHEAPTHRES = #wp * sortheap

Sort SortSort Heap Sort

Total sort memory (SHEAPTHRES / SHEAPTHRES_SHR define limit per partition)

Sort memory for one active sort (SORTHEAP defines allowed maximum)

Database Partition 0


Sort Overflow

A sort overflow occurs, if a sort requires more memory than defined by SORTHEAP:

The sort operation first continues in the Bufferpool.

If the Bufferpool is too small, the sort operation uses a temporary tablespace

This means sorting on disk!

Sort Sort

Bufferpool

Tempory TS

Sort

Sort

Sort Heap Sort

RealMemory

Disk


DB2 Monitoring Tools


The DB2 Memory Tracker

The DB2 memory tracker tool db2mtrk offers a complete report of

memory status for instances, databases, and agents.

This command outputs the following memory pool allocation information:

Memory type (e.g. bph = buffer pool)

Current size

Maximum size

Largest size (high water mark)

Agent who allocated memory pool (for private memory)


The DB2 Memory Tracker

Command Syntax:

>>-db2mtrk--+---+--+---+--+---+--+---+------------------------>

'-i-' '-d-' '-p-' +-m-+

'-w-'

>--+------------------------+--+---+--+---+----------------->

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