Copyright © 2014 EMC Corporation. All Rights Reserved. VNX Block Local Replication Principles Upon completion of this module, you should be able to: Explain

Copyright © 2014 EMC Corporation. All Rights Reserved.

VNX Block Local Replication Principles

Upon completion of this module, you should be able to:• Explain the business cases for VNX block local replication• List VNX SnapView and VNX Snapshot basic terminology • Explain operating principles for the following: VNX SnapView VNX Snapshot

VNX Block Local Replication Principles 1


VNX Block Local Replication Business Cases

• Primary goals Creation of point-in-time copies of data Support for consistent on-line backup or data replication Offload backup and other processing from production hosts

• Data copies can be used for purposes other than backup Testing, decision support scenarios, local data migration

• A successful recovery requires that consistent data was written to the backup media• SnapView supports consistency for Snapshots and clones• VNX Snapshots support Consistency Groups



SnapView Overview

• SnapView Snapshots Use pointer-based replication and Copy on First Write technology Make use of a Reserved LUN Pool to save data chunks Have three managed objects: Snapshot, Session, Reserved LUN Pool

• SnapView Clones Make full copies of the Source LUN (Classic, Thick , or Thin) Track changes to Source LUN and Clones in the Fracture Log Have three managed objects: Clone Group, Clone, Clone Private LUN

• SnapView Snapshots and SnapView Clones are managed by Unisphere Navisphere Secure CLI Admsnap



SnapView Terminology

Term Definition

Production host Server where customer applications are executed Source LUNs are accessed from the production host

Backup (secondary) host

Host where backup processing occurs Offloads backup processing from production host Snapshots and clones are accessed from backup host

Admsnap utility An executable program that runs interactively or with a script to manage clones and snapshots

Resides on the servers connected to the storage system

Source LUN Production LUN – the LUN from which replicas are made

Activate Maps a snapshot to an available snapshot session

Snapshot A point-in-time copy of a Source LUN

Reserved LUN Pool (RLP)

Private area used to contain Copy on First Write (CoFW) data Total number of Reserved LUNs is limited



SnapView Terminology (continued)

Term Definition

Snapshot session Defines a point-in-time designation by invoking CoFW activity for updates to the Source LUN

Snapshot session name

Name for a session that is used for subsequent operations (sessions should have meaningful names)

Chunk Granularity at which data is copied from the Source LUN to a reserved area

Copy on First Write (CoFW)

When a chunk is changed on the Source LUN for the first time, data is copied to a reserved area

Fracture The process of breaking off a clone from its source Once a clone is fractured, it can receive server I/O requests

Clone group Contains a Source LUN and all of its clones

Clone private LUNs Used for recording information that have been modified on the Source LUN and clone LUN that has been fractured



SnapView Features

• SnapView enabler allows use of Snapshots and Clones• Snapshots and Clones have high availability features

Resilient to SP and path failures (if PowerPath is installed), LUN trespasses, and non-disruptive upgrades

• Multiple point-in-time copies allowed• Restore to Source LUN capability

Primary host sees changes immediately Minimal disruption to production data processing

• Consistency of data across multiple objects Consistent session start, consistent clone fracture

• Simplified management with wizards



SnapView Technologies Comparison

• Access to point-in-time copy Snapshot data is immediately available for use Clones need an initial full synchronization, which is time-consuming

• Performance impact on Source LUN Snapshots use Copy on First Write, which increases response times Fractured Clones are independent of their Source LUNs

• Use of disk space A Snapshot uses around 20% of the space of its Source LUN A Clone occupies the same amount of space as its Source LUN

• Recovery from Source LUN loss or corruption Snapshots depend on a Source LUN for operation Clones can be completely independent of the Source LUN



SnapView Snapshot Limits


Parameters VNX5400

VNX5100

VNX5600

VNX5300

VNX5800

VNX5500

VNX7600

VNX5700

VNX8000

VNX7500

Max SnapView Snapshots per storage system

256 512 512 1024 2048

Snapshots per source LUN

8 8 8 8 8

Max SnapView Snapshot sessions per source LUN

8 8 8 8 8

Reserved LUNs per storage system

128 256 256 512 512


SnapView Clone Limits


Parameters VNX5400

VNX5600

VNX5800

VNX7600

VNX8000

SnapView Clones per storage system

256 1024 2048 2048 2048

SnapView Clones per source LUN

8 8 8 8 8

Clone groups per storage system

128 256 1024 1024 1024

Clone private LUNs per storage system

2 2 2 2 2Parameters VNX510

0VNX530

0VNX550

0VNX570

0VNX750

0SnapView Clones per storage system

128 256 512 1024 2048

SnapView Clones per source LUN

8 8 8 8 8

Clone groups per storage system

64 128 256 512 1024

Clone private LUNs per storage system

2 2 2 2 2


VNX Snapshot Overview

• VNX Snapshots 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 Unisphere SnapCLI



VNX Snapshot TerminologyTerm Definition

Primary LUN Production LUN – the LUN from which replicas are made

VNX Snapshot A point-in-time replica of a Primary LUN

Attach Maps a snapshot to a Snapshot Mount Point (SMP)

Detach Removes the mapping between a snapshot and a Snapshot Mount Point

Restore Restore the Primary LUN to a point in time copy

Unisphere SnapCLI utility An executable program that runs interactively or with a script to manage VNX Snapshots

Snapshot Mount Point (SMP)

Virtual LUN which can be attached to a VNX Snapshot to make it visible to a host

Consistency Group Persistent grouping of primary LUNs or Snapshot Mount Points

Snapshot family Pool LUN, all of its associated mount points, and all of their snapshots

Relocate on First Write (ROW)

When data is changed on the Primary LUN for the first time, data is written to another area in the Pool



VNX Snapshot Features

• VNX Snapshot enabler allows use of VNX Snapshots• Multiple point-in-time copies allowed• Restore to Primary LUN capability

Primary host sees changes immediately Minimal disruption to production data processing

• Consistency of data across multiple objects Consistency groups



VNX Snapshot Limits


Parameters VNX5400

VNX5600

VNX5800 VNX7600 VNX8000

VNX Snapshots per storage system

8000 8000 16000 24000 32000

VNX Snapshots per primary LUN

256 256 256 256 256

VNX Snapshots per Consistency Group

64 64 64 64 64

Consistency Group per storage system

128 128 128 256 256

VNX Snapshot Mount Points per storage system

1000 1000 2000 3000 4000

Concurrent Restore Operations per storage system

128 128 256 512 512


VNX Snapshot and SnapView Snapshot Comparison


VNX Snapshot Term SnapView Snapshots Term

Definition

Snapshot Session Point in time copy

Restore Rollback Restore primary LUN to point in time copy

Attach Activate Make the point in time copy accessible to a host

Detach Deactivate Remove the point in time copy from the host

Consistency Group n/a Persistent grouping of primary LUNs or Mount Points

Snapshot 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

Copyright © 2014 EMC Corporation. All Rights Reserved. 15

VNX Snapshot and SnapView Snapshot Features

VNX Block Local Replication Principles

Feature VNX Snapshots SnapView SnapshotsSnapshot Space Automatic in same pool Reserved LUN PoolMax Snapshots per source 256 8Max Snapshots per array 32,768 2048Snapshots of Snapshots Yes NoConsistent Snapshots Yes YesConsistency Groups Yes NoAutomatic Snapshot space management

Auto-Delete snapshots &Snapshot expiration None

Auto Naming Optional No

Source LUN type Pool LUNs, Consistency Groups, and Snapshot Mount Points All LUNs

Snapshot Description Yes NoRestore/Rollback Yes YesIn-Band Snapshot management Yes Yes


Summary

Key points covered in this module:• VNX block local replication business cases• VNX SnapView and VNX Snapshot basic terminology • VNX SnapView Snapshot operating principles• VNX Snapshot operating principles • VNX SnapView Clone operating principles


Documents

Copyright © 2014 EMC Corporation. All Rights Reserved. VNX Block Local Replication Principles Upon completion of this module, you should be able to: Explain