vnx snapshot

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VNX Snapshot

Upon completion of this module, you should be able to:• Describe VNX Snapshot operations• Manage VNX Snapshot and Sessions

VNX Snapshot 1


VNX Snapshot

During this lesson the following topics are covered: • Purpose of VNX Snapshots• VNX Snapshots requirements• VNX Snapshots managed objects• VNX Snapshots theory of operations

Lesson 1: VNX Snapshots: Theory and Operation

VNX Snapshot 2


VNX Snapshots • VNX Snapshots – virtual point-in-time copy of a LUN

Allows to create snapshots of pool-based LUNs Use pointer-based replication and Relocate on First Write (ROW)

technology Make use of the source LUN’s parent Pool to store original data Have three managed objects: Snapshot, Snapshot Mount Point,

Consistency Group• VNX Snapshots are managed by

Unisphere Navisphere Secure CLI SnapCLI

VNX Snapshot 3


VNX Snapshots Requirements Environment System Requirements

Hardware VNX Storage SystemTwo or more Servers (if the VNX Snapshots snap is to be accessed by a host), each attached to the VNX that will run VNX Snapshots

Storage System Software VNX Operating Environment for Block Release 32VNX Snapshot enabler

Management Software Unisphere UINavisphere Secure CLISnapCLI

Operating Systems HP-UXIBM AIXLinuxSolarisWindows Server

Refer to EMC Support Matrix for a complete list

VNX Snapshot 4


VNX Snapshots Managed Objects• Primary LUN

Pool LUN from which the snapshot is taken• Snapshot

Point-in-time copy of a LUN• Snapshot Mount Point

An object that is exposed to the host through a storage group• Consistency Group

Persistent grouping of primary LUNs or Mount Points

VNX Snapshot 5


• Scalability 256 snapshots per LUN Thin provisioned copies Lower write performance

impact

• Functionality Snapshot of a Snapshot RecoverPoint support Clone support

• Consistency Groups

VNX Snapshots Characteristics

VNX Snapshot 6

Primary LUN

2:00 pm Snapshot

4:00 pm Snapshot

6:00 pm Snapshot

Dev Snapshot

Patch 1 Snapshot

Patch 2 Snapshot


VNX Snapshot Mount Points• A Snapshot Mount Point is a container that holds SCSI attributes

Behaves like a LUN of the same size as the Primary LUN Added as a member LUN in the secondary host Storage Group

• A VNX Snapshot is attached to a Snapshot Mount Point (SMP) in order to allow host access to the replica data

• VNX Snapshots are easily switched on one SMP No SCSI rescan is required on the host

• Must have an attached Snapshot for data to be host-visible

VNX Snapshot 7


VNX Snapshot Consistency Group• A group of Primary LUNs or VNX Snapshot Mount Points• Snapshots can be made of the entire Group• Primary LUNs or VNX SMPs can be added to the Group

Snapshots may have more or fewer members as a result Snapshots being restored must have the same members as the

Group• Does not require application I/O to be stopped• Related terms

VNX Snapshot Set - a Snapshot of a Consistency Group VNX Snapshot Family – a group of Snapshots of the same LUN

VNX Snapshot 8


VNX Snapshot Term SnapView Term DefinitionSnapshot Session Point in time copyRestore Rollback Restore primary LUN to point

in time copyAttach Activate Make the point in time copy

accessible to a hostDetach Deactivate Remove the point in time

copy from the hostConsistency Group n/a Persistent grouping of primary

LUNs or Mount PointsSnapshot Family n/a Pool LUN, all of its associated

mount points and all of their snapshots

Primary LUN Source LUN Pool LUN that can be used by VNX Snapshots

Snapshot Mount Point Snapshot [LUN] LUN that host uses to access the snapshot data

SnapView and VNX Snapshot Terminology Comparison

VNX Snapshot 9


Snapshot Technology Comparison: Source LUN Writes

VNX Snapshot 10

Redirect on writeCopy on first write


Snapshot Technology Comparison: Snapshot Reads

VNX Snapshot 11

Read from a single placeRead from two places


VNX Snapshot Operations

VNX Snapshot 12

• Create a Snapshot• Create a Snapshot Mount Point (SMP)• Attach a Snapshot• Copy a Snapshot• Snap a Snapshot Mount Point (Cascading Snapshots)• Detach a Snapshot Mount Point• Destroy a Snapshot• Attach a Consistency Snapshot


Create a VNX Snapshot

VNX Snapshot 13

Primary LUN

Snap 1 (R/O)Creation time: 8pmLast modify time: Last modified by:Source LUN: LUN_20Primary LUN: LUN_20Attached LUN:


Lun_20

Snap 1

Snap 2

. . .


Create a VNX Snapshot Mount Point (SMP)

VNX Snapshot 14

Primary LUN



Lun_20

Snap 2

. . .

Snap 1 SMP1


Attach a VNX Snapshot to a SMP

VNX Snapshot 15

Primary LUN


. . .

Snap 1

Lun_20

Snap 2

Snap 2 (R/W)Creation time: 9pmLast modify time: Last modified by:Source LUN: LUN_20Primary LUN: LUN_20Attached LUN: SMP1

SMP1


Copy a VNX Snapshot (Snap of a Snap)

VNX Snapshot 16

Primary LUN

Snap 1 (R/W)Creation time: 8pmLast modify time: Last modified by:Source LUN: LUN_20Primary LUN: LUN_20Attached LUN:


. . .

Snap 2 Snap 3


Lun_20

Snap 1


Snap of a Snapshot Mount Point

VNX Snapshot 17

PrimaryLUN



. . .Lun_20

Snap 1

Snap 2.2Snap 2.1Snap 1 (R/O)

Creation time: 10pmLast modify time: Last modified by:Source LUN: SMP1Primary LUN: LUN_20Attached LUN:

Snap 2 (R/O)Creation time: 11pmLast modify time: Last modified by:Source LUN: SMP1Primary LUN: LUN_20Attached LUN: SMP1

Snap 2

SMP1


Detach a VNX Snapshot to a SMP

VNX Snapshot 18

Primary LUN


. . .

Snap 1

Lun_20

Snap 2

Snap 2 (R/W)Creation time: 9pmLast modify time: 11:47pmLast modified by:Source LUN: LUN_20Primary LUN: LUN_20Attached LUN: SMP1

SMP1X


Destroy a VNX Snapshot

VNX Snapshot 19

Primary LUN



Lun_20

Snap 2

. . .

Snap 1 SMP1

X


Attach a Consistency Snapshot

VNX Snapshot 20

CG1CG

Snap 1

R/W

Lun_21

Lun_20

SMPLUN_20

SMPLUN_21

Host 1 Host 2


VNX Snapshot

During this lesson the following topics were covered:• Purpose of VNX Snapshots• VNX Snapshots requirements• VNX Snapshots managed objects• VNX Snapshots theory of operations

Lesson 1: Summary

VNX Snapshot 21


VNX Snapshot

During this lesson the following topics are covered: • Displaying VNX Snapshots• VNX Snapshot expiration• Cascading VNX Snapshots• Restoring VNX Snapshots

Lesson 2: Managing VNX Snapshots

VNX Snapshot 22


VNX Snapshot Management

VNX Snapshots 23


VNX Snapshot Properties

SnapView Snapshots 24


VNX Snapshot Consistency Group Properties



Storage Pool Properties - VNX Snapshots



VNX Snapshot and SMP Creation



VNX Snapshot Expiration• Every VNX Snapshot may

have an optional expiration date

• Expired VNX Snapshots are destroyed at regular intervals VNX array scans for expired

snapshots once an hour • Set an expiration date only

after Auto-Delete is disabled • User is warned before

Snapshots are deleted



Cascading VNX Snapshots• VNX Snapshot of an attached Snapshot Mount Point


Not attached Attached


Restore• Use VNX Snapshot to restore a primary LUN or a SMP• Data in the LUN is changed to match the data in the snapshot

Does not change the “Restore Point” snapshot Return no the poin-in-time of the source data

• Used when recovering from data corruption• LUN with state ‘Initializing’ while being restored

Changes back to ‘Ready’ after the restore is complete• Restoring can change the LUN size

If the source snapshot was taken before the primary LUN expansion or shrinking



Restore Considerations• Restore with SnapView Snapshots and VNX Snapshots

Restore a primary LUN from a VNX Snapshot All SnapView session must be manually stopped

Restore a primary LUN from a SnapView Snapshot VNX Snapshots are unaffected

• Stop application access to the primary LUN• Flush the buffers for the drive



Restoring a Primary LUN



VNX Snapshot Configuration Wizard



VNX Snapshot

During this lesson the following topics were covered:• VNX Snapshot Management• VNX Snapshot properties• VNX Snapshot expiration and restore

Lesson 2: Summary

VNX Snapshot 34


VNX Snapshot SummaryKey points covered in this module:• VNX Snapshot provides a point-in-time virtual copy of pool-

based LUNs using ROW technology• A Snapshot Mount Point is a container that holds SCSI attributes,

behaves like a LUN, and is added to host Storage Group

VNX Snapshot 35

vnx snapshot

Documents

management of vnx snapshots

vnx snapshots snap

snapshots of pool

vnx snapshot copyright

vnx snapshot data

overview of vnx snapshot

snapview snapshots

vnx snapshotupon completion