ims logger enhancements - ims ug october 2017 dallas

Recent changes to help your IMS system run faster and

consume fewer resources

Adam Johanson

IMS Development

October 4, 2017

IMS Logger Enhancements

© 2017 IBM CorporationDallas / Ft. Worth RUG, October 2017 – Logger Enhancements

Important Disclaimer

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V12: Above-the-bar Storage for Log Buffers Introduced

ECSA savings

Specify BUFSTOR=64 on OLDSDEF

Block size must be multiple of 4K

OLDS must be extended format

Extended format OLDS allow for data set striping

Maintenance for Red Alert

–V13: PI71701; V14:PI71702; V15: in base code

V15: Apply PTF for PI86668 (to close soon)

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Log Buffers Above-the-Bar

Calculating ECSA Savings

–Buffer size * number of buffers

Number of buffers: BUFNO on OLDSDEF

Buffer size:

- BLKSZ on OLDSDEF card –or-

physical block size of the OLDS

Logger Exit (DFSFLGX0) and RSR Log Filter Exit

(DFSFTFX0) get address of log buffer

–Supplied exit DFSFTFX0 correctly handles 8-byte

address

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Data Set Striping for OLDS

Data set spread across multiple volumes

–Allows for concurrent I/Os

–OLDS for multiple blocks happen in parallel

Specifying extended format

–Data set type of “EXT”

–DATACLAS and STORCLAS attributes from DASD

personnel

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V15 Logger Enhancements


AS-IS Scenario: IMS Logging from 30,000 ft.

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(Flat file)


As-is: Purpose of the WADS

Performance

To write “small” chunks of data from a log buffer that has not yet been

written to the OLDS

Lets the user of the Logger resume processing quickly, knowing that

their data has been hardened

The WADS is a simple, small, sequential flat file

For performance, the IMS Logger currently builds its own channel

program to write data to the WADS

Exploiting new I/O features requires a change in the current design of

the WADS interface.8


V15: Use of DFSMS Media Manager for the WADS

Media Manager (MM) is a no-charge feature

IMS can now leverage zHyperWrite to reduce replication

latency

–zHyperWrite uses control unit mirroring to write to primary

and secondary devices in parallel

When available, IMS can also use zHPF for writing to the

WADS

–System z High Performance FICON

–Simply quicker I/O, not environment-specific

Positions Logger to easily exploit new hardware features9


To-Be Scenario:

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(VSAM LDS)


V15 Logger MM - Externals

The WADS will now be a VSAM Linear Data Set– Sample JCL provided

There is a parameter to enable/disable IMS’ use of zHyperWrite– <LOGGER> section of DFSDFxxx

ZHYPERWRITE=(WADS=YES)

– To MVS, zHyperWrite is enabled/disabled at LPAR level SYS1.PARMLIB(IECIOSxx) SETIOS HYPERWRITE=YES/NO

D IOS,HYPERWRITE

– zHPF used if it’s enabled D IOS,ZHPF

– BSAM started using zHPF for OLDS writes in z/OS 1.13 if zHPF is enabled

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V15 Logger Media Manager

Software requirements - zHyperWrite– Primary and secondary volumes must be in Metro Mirror

relationship in full duplex status

– Must be managed by HyperSwap

Software requirements - zHPF– Simply used if available on LPAR

Value of zHyperWrite parm added to /DIS OLDS output– APAR PI82325

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V15: zHyperWrite for the OLDS

Support added by APAR PI75575– Requires DFSMS APAR OA51385– Only a pre-req in terms of functionality– Not an SMP/E pre-req

OLDS must be defined as extended format– Already extended format if using BUFSTOR=64

Enable via:– ZHYPERWRITE=(OLDS=YES) in <LOGGER> section of

DFSDFxxx

– If enabled, but pre-reqs not met (OA51385, extended format, etc.), nothing bad happens Just not using zHyperWrite

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Encryption from 50,000 feet:

Data sets defined with a key label– Part of data set’s MVS catalog entry

Key label passed to ICSF to obtain “wrapped” key– ICSF – Integrated Cryptographic Services Facility– Maintains “wrapped” keys in CKDS

Cryptographic Key Data Set

– Wrapped key is a key that’s encrypted under the “master” key

Master key located in the Cryptographic Express (CEX) card

Wrapped key un-encrypted via master key within CEX card

Key never exists as plaintext in any address space, only the CEX card

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V15: WADS Encryption

To enable:– DFSMS APAR OA50569

APAR is for all access methods encryption

– Support added via PI84947

– Note: not enabled via an explicit parameter

– WADS must be: Defined as extended format Defined with a key label

After applying PI84947, migration to encrypted WADS can be done while IMS remains up– Procedure to be published in System Admin guide

– Involves using ‘extra’ WADS not currently in use by IMS

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Encryption Set-up

Ability to read encrypted WADS: access to key label

DASD volume-level utilities don’t require this access

Doc pointed to by OA50569:– http://publibz.boulder.ibm.com/zoslib/pdf/OA50569.pdf– Chapter 2: set-up

Keys created in CKDS for use by ICSF

New profile in FACILITY CLASS– STGADMIN.SMS.ALLOWDATASET.ENCRYPT

Access to key label via CSFKEYS class

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http://publibz.boulder.ibm.com/zoslib/pdf/OA50569.pdf


Enabling Encryption for OLDS/SLDS

Any supported release of IMS!

https://www.ibm.com/support/knowledgecenter/SSEPH2_15.1.0/com.ibm.ims15.doc.sag/system_admin

/ims_dataset_encryption.htm





Requires OA50569

OLDS:

– Can do while IMS remains up via ‘extra’ OLDS and commands:

/STO OLDS x

/STA OLDS x

SLDS

– Change skeletal JCL member to specify DSKEYLBL for SLDS/RLDS

– Or specify a DATACLAS with an associated key label

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https://www.ibm.com/support/knowledgecenter/SSEPH2_15.1.0/com.ibm.ims15.doc.sag/system_admin/ims_dataset_encryption.htm



Logger Setup Recommendations


Dual Logging

Dual OLDS– OLDSDEF MODE=DUAL in <LOGGER> section of DFSDFxxx

Dual WADS– WADSDEF MODE=DUAL

Redundancy of data

Different packs for OLDS and WADS– Don’t want to lose both simultaneously– Multiple OLDS can be on same pack, within reason

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Buffer Size

Specified by BLKSIZE on OLDSDEF -or-

– Physical block size of OLDS

Sizes 6K – 30K– Multiple of 2K for 31-bit buffers– Multiple of 4K for 64-bit buffers

Live in common storage– ECSA if using BUFSTOR=31 (default)

Tradeoffs:– Smaller buffer sizes make IOS busier– Larger buffer sizes take longer to fill and write out– Desire little-to-no wasted space on track

– 24K: good compromise and 2 buffers fit on track20


Number of OLDS

IMS has maximum of 100 (numbered 0-99)

When all OLDS are awaiting archive, IMS hangs

Not looking for “exact” number, just a comfort level

Goal:

– Easily handle high-volume period

– Not have so many that more can’t be added when needed

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Size of the OLDS

Largely dependent on frequency of switches

– IEBEYEBALL messages DFS3257I during high-volume

Efficient use of DASD

– Little-to-no empty space on pack

– Example: A model-3 3390 pack contains 3,339 cylinders

OLDS of 1,000 cylinders wastes 339 cylinders on pack

OLDS can be 1,113 cylinders for 3 OLDS/pack

OLDS can be 1,669 cylinders for 2 OLDS/pack

Size all of them the same

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Recommendations for Archive

Own scheduling class in JES

– No contention for initiators

Unique job names

– In GENJCL, job name can include timestamp

Symbolic keyword %ARTIME Granular to tenth of a second

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Questions?

ims logger enhancements - ims ug october 2017 dallas

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