High Availability Options for IBM i

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with Glenn Robinson and Ash Giddings

High Availability Options for IBM i

HelpSystems Corporate Overview. All rights reserved.

Ash GiddingsProduct Manager

HelpSystems

Today’s Presenters

Glenn RobinsonPower Systems Architect

RSI Consulting


• What is high availability?• Current options• Which method is best?• Additional resources• Q&A and recap

Agenda

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What is high availability?



In information technology, high availability refers to a system or component that is continuously operational for a desirably long length of time.

Availability can be measured relative to "100% operational" or "never failing."

24/7



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Current options


HA/DR options for IBM i

• Logical replication– Replication at the object level provided by third-party software

• PowerHA geographic mirroring– Replication by the IBM i operating system– Block-level replication of an independent ASP (IASP) to another IBM i LPAR– Internal or external storage– Requires PowerHA license

• Storage replication– Replication by the storage system, e.g. V7000– Block-level replication of an IASP or an entire system– External storage only


Logical replication


Pros– Target can be used for read-only access to replicated data– Journaling is mandatory– Source and target LPAR are both active

Cons– Requires third-party software– Operating system overhead; depends on how much data is being replicated– Objects to be replicated need to be defined to the replication software– Estimates denote around 182 man-hours per year for monitoring

Comments– Popular customer choice– Data replicated over IP only

Logical replication


PowerHA geographic mirroring


• Pros– All data is copied from source to target as this is disk mirroring– Choice of synchronous and asynchronous replication– Minimal amount of monitoring required

• Cons– Requires PowerHA license on each LPAR– Only an IASP can be mirrored– Operating system overhead; depends on how much data is being replicated– The IASP can only be accessed by one LPAR at any one time– Fairly complicated PowerHA clustering configuration

• Comments– Replication over IP only– Journaling not required but is recommended– Not widely implemented

PowerHA geographic mirroring


Metro Mirror

Global Mirror

Global Mirrorwith Change Volumes

Storage-based mirroring


Disaster recovery testing without interruption

• Storage replication from site 1 to site 2

• Create a point-in-time FlashCopy of the volumes at site 2

• Run an LPAR over the J2 volumes and test DR

• No interruption to storage replicationat any point

• Gone are the days of 4- to 5-day engagements with your DR hardware provider!!!

Site 1 Site 2

J 2

H 1 H 2

Flash Copy

Global Copy


• Pros– All data is copied from source to target as this is disk mirroring– No overhead on the operating system; this is completely transparent to IBM i– Choice of synchronous and asynchronous replication– Full system and/or IASP replication can be configured– Simple configuration on storage– Minimal amount of monitoring required

• Cons– The target LPAR cannot be active if full system replication is being used– Remote mirroring license required on most storage systems– Knowledge of storage subsystem required for initial configuration

• Comments– Replication over IP or fibre– Becoming increasingly popular– Journaling not required but is recommended

Storage-based mirroring


Logical replication

Geographic mirroring

Storage-based replication

Source and target active at all times

Y Y* N

Journaling mandatory Y N NOverhead on IBM i OS Y Y NAll objects replicated N Y YPowerHA required N Y NTarget is a clone of the source

N Y Y

Target can be used for backups

Y Y** Y***

Requires IASP N Y N

*Only SYSBAS is active on both source and target ** Only if replication is stopped*** Requires use of FlashCopy snapshots

Summary of options

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Which option is best for me?


• Assess each LPAR on a needs basis

• A combination of both logical and storage replication may be the best fit

• There is no right or wrong answer

Which option is best for me?


• Does my LPAR require 24/7 availability?– Use logical replication

• Do I require the source and target LPAR active at all times?– Use logical replication

• Do I want to run my production LPAR backups on another LPAR?– You can use both logical replication and storage replication

• Do I need simplified replication for my LPAR?– Use storage-based replication

Questions to ask


• FlashCopy backups using storage software

• FlashCopy within VIOS shared storage pools

• BRMS integration with FlashCopy

• Clone LPARs in seconds

• Share IASPs without a PowerHA license

Other ideas to consider


• IBM i Advanced Copy Services– http://tinyurl.com/o5t4k8b– Full System Replication for SVC and Storwize

Provides IBM i commands to configure and manage remote mirroring– Full System Copy Services Manger

IBM i commands to create a snapshot of an LPAR and back up to tape on another LPAR

Provides the capability to quiesce SYSBAS instead of having to power down the LPAR

» No interruption to the users– BRMS integration

BRMS can be used to backup an LPAR clone but update the BRMS database on the source LPAR

IBM Lab Services offerings

http://tinyurl.com/o5t4k8b

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About HelpSystems


Solutions portfolio



Template approach

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Q&A and recap


• What is high availability?• Current options• Which method is best?• Additional resources

Q&A and recap


Contact Us

Website:www.helpsystems.com/halcyon

Ash GiddingsProduct Manager

[email protected]

Glenn RobinsonPower Systems Architect

RSI [email protected]

Telephone:800-328-100+44 (0) 1733 234995

http://www.helpsystesm.com/halcyon

mailto:[email protected]?subject=Request%20more%20information




Software

High Availability Options for IBM i