snapview clones

Copyright © 2014 EMC Corporation. All Rights Reserved.

SnapView Clones

Upon completion of this module, you should be able to:• Describe SnapView Clone operations• Manage SnapView Clones

VNX Snapview Clones 1


SnapView Clones

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

Lesson 1: SnapView Clone: Theory and Operation

2VNX Snapview Clones


SnapView Clones• SnapView Clone – a full copy of a LUN internal to a storage

system• Population latency

Clones take time to populate (synchronize) Data in the LUN must be duplicated

• Protected No changes will be made to the clone UNLESS the user writes to it

• 2-way synchronization Clones may be incrementally updated from the source LUN Source LUNs may be incrementally updated from a clone

• Copies real data Clone must be EXACTLY the same size as Source LUN



SnapView Clones Operations• Create Clone Group

Changes LUN to source LUN• Add clone to Clone Group

Changes LUN to clone• Synchronize Clone

Data copied from source LUN to clone• Fracture clone (may be a consistent operation)

Stops updating of clone with new source LUN data• Remove clone

Clone becomes an independent LUN Cannot be synchronizing or reverse synchronizing

• Destroy Clone Group Source LUN becomes an independent LUN



Clone Initial Synchronization• Copy contents of source LUN to clone

Overwrites clone with source LUN data Host access allowed to source LUN at all times No host access to clone while not fractured


. . .

Production Host

Backup Host

X Clone 1 Clone 2 Clone 8

Source LUN


Clone Private LUN (CPL) and Fracture Log• Fracture Log

Bitmap stored in SP memory Tracks modified extents between source LUN and each clone Allows incremental resynchronization – in either direction Determines extent size

1 block for each GB of source LUN size, with a minimum of 128 KB Example: 512 GB clone. Extent size = 512 blocks = 256 KB

• Private LUN for each SP Must be 1 GB or greater Used for all clones owned by the SP No clone operations allowed until CPL created Contains persistent Fracture Logs Classic LUNS only



Clone Reverse Synchronization• Restore source LUN with contents of clone

Overwrites source LUN with clone data Host access allowed to source LUN No host access to clone Source LUN instantly appears to contain clone data


. . .

Production Host

Backup Host

X Clone 1 Clone 2 Clone 8

Source LUN

X

X

X


Reverse Synchronization and Protected Restore• Non-Protected Restore

Host → source LUN writes mirrored to clone When Reverse Synchronization completes:

Reverse-synchronized clone remains unfractured Other clones remain fractured

• Protected Restore Host → source LUN writes not mirrored to clone When Reverse Synchronization completes:

All clones are fractured Protects against source LUN corruption

Configure at the individual clone level Must be globally enabled first with ‘Allow Protected Restore”

checkbox



Trespassing Source LUNs and Clones• Source LUN Trespass

Peer SP acquires clones Peer SP acquires Fracture Logs (through CPL) Peer SP resumes any synchronization operations

• Clone Trespass User or host can initiate trespass of a fractured clone

Desirable for load balancing across SPs Fractured clone need not be on same SP as source LUN Synchronization trespasses clone as necessary



SnapView Clones

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

Lesson 1: Summary



SnapView Clones

During this lesson the following topics are covered: • Clone configuration• Creating and populating Clone Groups

Lesson 2: Clone Configuration

11VNX Snapview Clones


Configuring the Clone Private LUNs



Creating a Clone Group



Adding a Clone to a Clone Group



Clone Group Properties



Clone Operations



Clone Operations - Consistent Fracture



Clone Time of Fracture• Allows the user to know the date/time when the Clones images

were administratively fractured • Clones will stamp the time ONLY when the clones were

administrative fractured by the user and the images were a point in time copy (consistent state)

• The time will be stored persistently inside the current clones private area in PSM

• All Clones involved in a Consistent Fracture operation reports the same time of fracture

• Private LUN for each SP



Clone Configuration Wizard



SnapView Clones

During this lesson the following topics were covered:• Clone Private LUN configuration • Clone operations

Lesson 2: Summary



SummaryKey points covered in this module:• SnapView Clone is a full copy of a LUN internal to a VNX storage

system• Clones take time to duplicate data from source• Clones must be exactly the same size



This slide is intentionally left blank.


snapview clones

Documents