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 Giddings
Product Manager
HelpSystems
Today’s Presenters
Glenn Robinson
Power Systems Architect
RSI Consulting

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

UP NEXT...
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

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 Mirror
with 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 replication
at 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 N
Overhead on IBM i OS Y Y N
All objects replicated N Y Y
PowerHA required N Y N
Target 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

UP NEXT...
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

Solutions portfolio

Template approach

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

Contact Us
Website:
www.helpsystems.com/halcyon
Ash Giddings
Product Manager
HelpSystems
ash.giddings@helpsystems.com
Glenn Robinson
Power Systems Architect
RSI Consulting
glenn.robinson@rsipvm.com
Telephone:
800-328-100
+44 (0) 1733 234995

High Availability Options for IBM i

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