Copy / refresh data off back end of IBM DS8000 Global Mirror, using Global Copy Prepared for IBM Strategic Outsourcing John Sing/San Jose/IBM April 4,

Copy / refresh data off back end of IBM DS8000 Global Mirror, using Global Copy

Prepared for IBM Strategic Outsourcing

John Sing/San Jose/IBM April 4, 2012

© 2012 IBM Corporation2

IBM System Storage DS8000 Copy Services

31 years of experience with IBM in high end servers, storage, and software

– 2009 - Present: IBM Systems Group Executive IT Consultant – IT Strategy and Planning, Enterprise Storage, Big Data Analytics, HA/DR/BC, WW Technical Marketing

– 2002-2008: IBM WW Business Continuity, IT HA/DR, IT Strategy

– 1998-2001: IBM Storage Subsystems Group - Enterprise Storage Server Marketing Manager, Planner for ESS Copy Services (FlashCopy, PPRC, XRC, Metro Mirror, Global Mirror)

– 1994-1998: IBM Hong Kong, IBM China Marketing Specialist for High-End Storage

– 1989-1994: IBM USA Systems Center Specialist for High-End S/390 processors

– 1982-1989: IBM USA Marketing Specialist for S/370, S/390 customers (including VSE and VSE/ESA)

[email protected]

You may follow my daily IT research mini-blog– http://www.delicious.com/atsf_arizona

IBMers may access my IBM Intranet webpages:– http://snjgsa.ibm.com/~singj/

John Sing



Global Copy

Fibrechannel connectivity between disk subsystems Extension equipment used to provide connection over WAN

Disk subsystem based asynchronous replication solutionSupported on ESS, DS6000 and DS8000 for all data types

Bitmaps used to track data required to be sentMinimal performance impact and does not use additional cache

Supports very long distancesMigrations performed from UK to Germany, Chile to Spain etc

With Global Copy an outage is required to create consistent copyUsing Global Mirror or converting to Metro Mirror allows migration to be tested without production outage

Failover/failback capability reduces requirements for full copyIncremental changes copied after a test and in case of return to original location

Migrating data with Global Copy



Definitions: Global Copy

Data migration / copy

Use Global Copy to effect large data movement

With minimal relocation effort and minimal amount of volumes

Source Remote

B M

1. Setup DS8000 Global Copy environment2. Start and monitor initial copy B to M3. SUSPEND with Go-To-Sync Consistency Group4. Establish incremental change tracking on both B and M5. Test on M6. Once test over, reset and incrementally resync B to M for

next test of cutover. Automatically resets M properly



VOL BPPRCBITMAP

01040053000020

Objective: efficiently move data with low overhead, keep

the line highly utilized

Global CopyNon-synchronous

Transfer

SECONDARYPRIMARY

(Fuzzy)

VOLUMEM

VOLUMEB

DS8000, DS6000, ESS Global Copy is continuous cycle through volume bitmap – Updates to tracks/sectors on volume/LUN noted by bitmap– Send only changed tracks, using pre-deposit write– If all changes in cache, send changed sectors only– No host I/O wait for updates to be sent to the secondary

DS8000 Global Copy Operation

0

0

00

0000

0

VOL MPPRCBITMAP

Note that DS8000 Global Copy does not send data in same order it was written– Objective is to move large amounts of data with low overhead, and

keep telecom line very well utilized

‘M’ consistency can be created by: – Quiesce workload at site B and allow M to catch up – Go to Sync (command copying to become Metro Mirror)– Add the Global Copy volumes to a DS8000 Global Mirror sessionIncoming

Writes

– Note that the remote site data is in a 'fuzzy’ state



General Data Center migration concept using DS8000 Global Copy

Overview of Global Copy use for data center migration

Production Future PROD location

B M

1. Setup Global Copy (PPRC-XD) environment2. Start and monitor initial copy B to M3. SUSPEND with failover/failback change tracking on

both B and M 4. Test cutover on M5. Once test over, reset and incrementally resync B

to M for next test of cutover. This automatically resets M properly

6. After multiple successful tests, execute cutover

We will adapt this methodologyfor use in your GM

environment



Other ways to use DS8000 storage replication

Point-in-Time followed by remote mirror

A

B

C

D

Point-in-Time followed by remote mirror followed by Point-in-Time



Other ways to use DS8000 storage replication - 2

A C

B

A C

D

Point-in-Time from a remote mirror primary

Make a Point-in-Time safety copy of remote mirror



Other ways to use DS8000 replication

A C

G

Async mirroring for Out of region recovery



Other ways to use DS8000 replication

A C

GE

Migrate data from both ends of the A to C D/R link

Older generation A devices to newer generation E devices

Older generation C devices to newer generation G devices

Without impacting D/R protection on A to C link



Incremental Resynchronisation bitmaps

The Global Copy and Global Mirror incremental resynchronisation functions allows bitmaps to be created for sending only changed data

Avoids ever having to do full copy

Disk subsystems can track what data blocks have changed, and can send only changed data

Minimizes time, saves bandwidth



Notes

Assume that building automation of all these steps is a necessity

Migrate a test systems first, to get experience that can be applied to subsequent migration of large systems



Notes

Circumventions may be possible to avoid using telecom to do initial loads over telecom

– By doing tape dumps followed by resyncs

– Those possibilities are outside the scope of this version of this document



Initial load ofdata to volumes at Cloud for testing



Start testing of migration data to Raleigh

A B

C

D

GM CGvolumes

GM

GC

Practice D/R Testvolumes

Original

D/R

Raleigh

M

While GM continues to run• Start Global Copy pairs B to M • B = GC primaries • M volumes = GC secondaries • M volumes = New Production

volumes for testing and eventual production

• This does initial load of M

GM = Global Mirror

GC = Global Copy



Bring data to consistent statefor test at Raleigh

Goals are:

•No production outage or impact•Minimize impact to DR protection to greatest extent reasonable



Definitions:

Failover/Failback

Suspend

Failover:– Is always issued to a secondary volume– Tells that volume that "now you're a suspended primary"– Starts change tracking– Is never issued to a primary volume

• You'll get a message: "improper state"– You do specify the secondary and primary volumes– Does not have to have paths/connections available to the

primary, will work if there's no connections Failback:

– Is issued to whichever volume is going to become the new primary

– That new primary then communicates to the secondary volume

– You always must specify which volume is primary and which volume is secondary

– Hence, must have paths and connections active and avail to the secondary, else command won't complete

Suspend– Stops mirroring of data to the secondary volume– Starts keeping record of the primary volume tracks that

are updated. That info will be used later when the pair is re-established, to copy just the updated tracks

– You specify the primary and secondary volumes to be suspended

‘B‘ Primary

‘M’ Secondary



Initial starting point

A B

C

D

GM CGvolumes

GM

GC


OriginalD/R

M

While GM runs:

• Global Copy is copying changes B to M thus keeping M quasi-current

• Data lag at M is short• Only a few seconds

GM = Global Mirror

GC = Global Copy

RaleighGreen = prodOrange = inconsistent dataBlue – consistent data



Start process to bring M volumes to consistent state

A B

C

D

GM CGvolumes GC


OriginalD/R

M

• Issue Pause GM session A->B• GM stops forming consistency

groups

• Issue Suspend to GC pairs at A• Starts incremental change

tracking at AGM sessionPause and SuspendGC pairs




Incrementally forward Consistency Group C volumes to Raleigh M

A B

C

D

GM CGvolumes GC


Original

D/R

M

• At B:• Issue Suspend with Failover to B

volumes• Makes B suspended primary; note that

B to M is still running • Restore GM CG onto B

• Revertible check FlashCopies• Fast Reverse Restore C to B• Recreate FlashCopies B to C

• Wait till B->M Global Copy has reached zero out of sync tracksGM session

Pause and SuspendGC pairs

RPO at D/R is aging while GM A-B is stoppedHowever, this process to refresh M will be fast

As M was only a few seconds behind BTherefore, elapsed time until GM A to B is restarted, will be short

Raleigh



Status of B and M after new CG copied thru B to M

A B

D

GM CGvolumes GC


Original

D/R

M

• GC completes copy of incremental changes B to M• Duration of the remaining

incremental changes is proportional to:• Amount of out of sync data not

yet copied to M plus…• Amount of any data that needs

to be reset at M• Soon, B =M

C

GM sessionPause and SuspendGC pairs




Suspend Global Copy pairs B->M

A B

D

GM CGvolumes


Original

D/R

• As soon as B =M

• Issue Suspend to B volumes to start change tracking B to M

• Issue Failover to M volumes• Makes M suspended primary• Starts incremental change

tracking at M

C

M Volumes becomeSuspended Primaries, with change tracking

on

M

GM sessionPause and SuspendGC pairs

GC suspendedat B to M with

changetracking

on




Restart GM Original - D/R

A B

C

D

GM CGvolumes


Original

D/R

M

• Issue Global Copy Failback to A volumes• Causes resync to start on GC

pairs on A->B (incremental changes only sent)

• Then restart GM session A to BA standard GM resume / start

• D/R on Original – D/R is re-established

GM

GC resync

M Volumes areSuspended Primaries, with change tracking

on


changetracking

on




Copy data from M volumes to Cloud

A B

C

D

GM CGvolumes


Original

D/R

M

• Can now copy consistent test data M to Cloud• Changes are tracked on M • For later reset during next

refresh cycle

GM

Cloud

M Volumes areSuspended Primaries, with change tracking

on


changetracking

on




When finished with test, use Global Copy to refresh B to M, in prep for next refresh cycle

A B

C

D

GM CGvolumes

GM

GC


Original

D/R

M

While GM continues to runAt B: • Issue a Failback to B• Makes B primary and M

secondary• Resync of changed data

starts flowing again from B to M

• Also resets any data changed at M during test

GM = Global Mirror

GC = Global Copy




Thank YouThank You

Merci

Grazie

GraciasObrigado

Danke

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Documents

Copy / refresh data off back end of IBM DS8000 Global Mirror, using Global Copy Prepared for IBM Strategic Outsourcing John Sing/San Jose/IBM April 4,