IBM Power Systems
High Availability Considerations
IBM i
Erik Rex
Cert Consultant Specialist
IBM Danmark aps
rex@dk.ibm.com
© 2012 IBM Corporation
Downtime
Causes Of Downtime
Solution Required

Disaster
Recovery
High
Availability
Downtime refers to a period of time or a
percentage of a time span that a machine
or system (usually a computer server) is
offline or not functioning, usually as a
result of either system failure (such as a
crash or routine maintenance.
Source: IBM HA Presentation,
Eric Hess, April 2001

(Continuous
Operations)
* ‘HA’ generally refers to solutions that provide BOTH recovery and availability. Not
all technologies provide a solution for BOTH…iTera 5.0 HA does
Reliability is not the same as Availability!
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© 2012 IBM Corporation
Business Continuity is:
 Capability of a business to withstand outages and operate
mission critical services normally and without interruption per
a pre-defined Service Level Agreement
– Solution must address data, operational environment, applications,
the application hosting environment, and the end user interface
– Requires a collection of services, software, hardware, and procedures
to be selected, described in a documented plan, implemented, and
practiced regularly
 Includes both Disaster Recovery (DR) and High Availability
(HA)
– DR addresses the set of resources, plans, services and procedures to
recover and resume mission critical applications at a remote site in the
event of a disaster
– HA defined as the ability to withstand all outages (planned, unplanned,
and disasters) and to provide continuous processing for all mission
critical applications
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© 2012 IBM Corporation
What is a Service Level Agreement (SLA)?
 General:
– Contractual service commitment.
– A document that describes the minimum performance criteria a provider
promises to meet while delivering a service.
– Typically also sets out the remedial action and any penalties that will take
effect if performance falls below the promised standard.
 Relative to Availability:
– Commitment to the business describing the level of availability for IT services
that support critical business solutions.
– Addresses when IT services are expected to be fully operational, when they
may be running degraded, and when they won’t be available
– Driven primarily be importance of IT services in providing business solutions,
cost factors, and realism.
 Many factors involved
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© 2012 IBM Corporation
Application Resilience
Combine with Data Resilience for complete solution
Fully transparent
• Full resilience with automatic restart & transparent failover
• Users repositioned to last committed transaction
• No data loss, no sign-on required, no perceived loss of server;
only delay in response
Semi-transparent:
• Automatic application restart & recovery to last transaction boundary
• The resilient data & the application restart point match exactly
Huh?
Did
something
happen?
Semi-automatic:
• Automatic application restart & recovery to some architected
application “restart” point
• Normally consistent with state of data, but user may have to
manually match application to position of data
Basic application failover:
• Automatic application restart after outage
• User manually repositions within application
HA enabled
applications
and iSeries
Clusters
Checkpoint restart.
Not too bad .
iSeries
Clusters
Data
resiliency
Single
Server
Start over.
Where's all my work?
No application recovery:
• Users manually restart application with resilient data
• User determines where to resume work
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© 2012 IBM Corporation
The Fundamentals
Recovery or Continuity ?
Clustering
Application Resiliency
Data Resiliency – IASPs, Replication
Transaction Integrity - Journaling
Data Protection - Raid 5 & Mirroring
Data Replication alone is not sufficient for HA
Clustering, Automation and application resiliency completes the equation
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© 2012 IBM Corporation
Clustering for HA/DR
 Clustering is the default deployment for
HA/DR in the mainframe and Unix
marketplace
 With PowerHA SystemMirror, clustering is
available to our IBM i customers
 Provides for automated failover – minimal
IT operations involvement
 Planned and unplanned outage
management
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© 2012 IBM Corporation
Clustering
 A property of the Operating System
 Provides the logical connections
between resilient data groups
 Can enable the automation of
physical and logical switching
 Can enable a resilient application
to be “switched”, activated and
repositioned to a defined state
 Enables the automatic sequencing
of events that bring the user,
application and data to a coherent
production state automatically
 Application design is the primary
limiting factor
8
Application
Resiliency
Data
Resiliency
Replication
and
Switched
IASPs
Cluster
Management
iSeries Navigator
or partner products
High
availability
cluster
enabled
applications
APIs
Cluster Resource Services
Base IBM i cluster functions from IBM





Heart beating
IP Address Takeover
Reliable internal cluster communications
Switchover administration
Distributed activities
© 2012 IBM Corporation
Data Resilience Technologies
 Logical Replication
– Business partner software product
•Vision Solution, Quick EDD, iCluster ….
 Switchable Device
– Switchable IASPs
 Operating System Storage
Management based Replication
– PowerHA System Mirror Cross-Site
Mirroring (XSM) with Geographic
Mirroring
 SAN Storage Server based
Replication
– SAN Metro/Global Mirror used with
PowerHA IBM I Advanced Copy
Service toolkit
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© 2012 IBM Corporation
Logical Replication
 Second copy of data is generated logically identical
to first
 Replication done on object basis (file, member, data
area, program, etc.) near real-time
Backup
(target system)
Tape
 Normally done via a business partner software
product
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© 2012 IBM Corporation
Logical Replication
Backup
(target system)
Tape
 Widely deployed data resiliency topology for Power IBM i
– Typically deployed via an HA Business Partner solution package
– Replication done on object basis (file, data area, program, etc.) near real-time
• Done at the lowest unit of change for the object, e.g. record level for database files
• Otherwise, done on entire object when change detected by replication software
• Solution Packages can use IBM i Remote Journaling as efficient, reliable transport
mechanism.
 Benefits:
– Rapid activation of production environment on backup server via role-swap operation
– Replicated data can be concurrently accessed for backups or other read-only apps
– Minimal recovery is needed when switching over to the backup copy
 Considerations:
–
–
–
–
11
Complexity of setup and maintenance
Modification of ‘live’ copies of objects on backup server
Lag time between changes on source being available on backup server
Consistency between journaled and non-journaled objects
© 2012 IBM Corporation
Switchable IASPs
 Independent Auxiliary Storage Pools (IASPs)
– IBM i Option 41 - High Availability Switchable Resources
– Switch disks from one system to another
 Benefits:
–
–
–
–
–
Simplicity
Data is always current (no copy to synchronize)
No in-flight data to lose
Minimal performance overhead
Supports integrated environments (Windows, Linux)
as well as IBM i
 Considerations:
–
–
–
–
12
Setup DASD configuration, data, and application structure
Single copy of data (mirroring recommended to protect data, reduce SPOFs)
No concurrent access from both hosts
HW restrictions (distance, conc maint)
© 2012 IBM Corporation
Switchable Devices
PowerHA Basic Concepts (for IBM i clients)
Admin domain
(IASP)
Application data
aka (volume group)
 The underlying data resiliency is not based on replication it is based on a pool of disk which is
shared and switchable between nodes in the cluster
 PowerHA SystemMirror enables the cluster nodes to behave as resource for the applications in
the event of an outage
 Admin Domain takes care of the sysbas data…(fyi…no you do not use a software replication
product to replicate the Admin Domain data)
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© 2012 IBM Corporation
PowerHA SystemMirror Strategy
 Deep Integration
– Cluster Aware IBM i
– SLIC based event processing
– Centralize cluster topology management
 Ease of deployment & ease of use
– System Director Navigator management
– Discovery based deployment
– Cluster wide security
 Multi-Site & Disaster Recovery
– Differentiate with IBM storage
– Integrated IBM copy services
 Solution Package Optimization
– Standard Edition, Enterprise Editions
15
© 2012 IBM Corporation
PowerHA SystemMirror
(Cross-Site Mirroring) (XSM) with Geographic Mirroring
 Second copy of data in an IASP is generated logically identical to first
 Changes to production IASP replicated to second copy of IASP thru another system
 Operating system storage management based replication solution
Primary
(source system)
Backup
(target system)
Production
Data
Backup
16
Mirror
Copy
© 2012 IBM Corporation
PowerHA
Cross-Site Mirroring (XSM) with Geographic Mirroring
 Mirroring of IASP data via IBM i storage management to a second server
– XSM Included in Option 41 of OS
– Enables switching or automatic failover to mirrored copy of IASP
 Benefits:
–
–
–
–
–
Primary
(source system)
Same as switched device
Production
Data
Two copies of IASP data
Can be local or remote (Sync or Async)
Ease of deployment and operation
Supports integrated environments (Windows, Linux)
as well as IBM i Client partitions
– Heartbeat monitoring with automate failover or manual switchover
Backup
Backup
(target system)
Mirror
Copy
 Considerations:
– Performance impacts of synchronous operation, distance, bandwidth, latency
– Mirror copy cannot be concurrently access
– Lengthy full data re-synchronization
17
© 2012 IBM Corporation
PowerHA Basic Concepts
Admin domain
Geomirror
 Internal disk is not switchable (LUNs required), you use geomirror with internal disk configurations
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© 2012 IBM Corporation
PowerHA Metro/Global Mirror with IBM i Advanced Copy Services toolkit
 Replication of iASP data at storage controller level to Backup SAN using Metro
or Global Mirror
– Metro or Global Mirror generates a second copy of the IASP on another Storage
server
– Toolkit part of Power IBM i Advanced Copy Services for IBM i offering
– Combines Metro/Global Mirror, PowerHA, IASP, and IBM i cluster services
– Coordinated switchover/failover
 Benefits:
– Remote copy and coordinated switching without an IPL
– Can combine with FlashCopy for backup window reduction
 Considerations:
–
–
–
–
19
Performance impacts of synchronous mode: distance, bandwidth, latency
Mirror copy cannot be concurrently accessed
Asynchronous mode requires IBM SAN Global Mirror
Requires tools and services to deploy
© 2012 IBM Corporation
PowerHA Enterprise Edition Two Node Cluster
Admin domain
*SYSBAS
(Prod)
POWER7
IBM i
IASP
(Switchable)
HA
POWER7
IBM i
Production
Metro Mirror
Global Mirror
IASP
F
l
a
s
h
C
o
p
y
DR
IASP
Flash
Backup
*SYBAS
(Backup I)
DS8000
SVC
Storewize V7000
DS8000
SVC*
Storewize V7000*
Local Site
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*SYSBAS
(DR)
POWER7
IBM i
©
DR Site
* Initially available English only via prpq 5799 HAS
© 2012 IBM Corporation
PowerHA Enterprise Edition Three Node Cluster
DR Site
LUN
Group
(active)
Production
Admin domain
*SYSBAS
(Prod)
POWER7
IBM i
IASP
(Switchable)
HA
*SYBAS
(Backup I)
POWER7
IBM i
DS8000
SVC*
Storewize V7000*
Local Site
21
*SYSBAS
(DR)
MetroMirror
Global Mirror
F
l
a
s
h
C
o
p
y
IASP
DR
IASP
Flash
Backup
*SYBAS
(Backup I)
POWER7
IBM i
DS8000
SVC*
Storewize V7000*
©
DR Site
© 2012 IBM Corporation
Redundant VIOS I/O Virtualization
 Redundant VIOS partitions provide
two paths to attached SAN storage
VIOS
– AIX, i, and Linux partitions
– One set of disk
– Client partitions use MPIO
 Redundant VIOS partitions
provide access to mirrored SAN
storage
VIOS
Power Hypervisor
VIOS
– AIX, i, and Linux partitions
– Mirrored set of disk
– Mirroring done by client
partitions (e.g., IBM i)
VIOS
Power Hypervisor
Note: Redundant VIOS partitions are not supported on BladeCenter JS12, JS22, JS23, and JS43
22
© 2012 IBM Corporation
PowerVM can Help Manage Risk
 Business and IT security and resiliency are as critical as ever, and must be
dynamic and intelligent in order to match the speed of business change
 PowerVM Live Partition Mobility
– Move running IBM I, AIX and Linux partitions between systems
– Using VIOS
Virtualized SAN and Network Infrastructure
√ Eliminate planned outages and balance workloads across systems
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© 2012 IBM Corporation
IBM i Capacity Back Up (CBU) Licensing Example
Planning
 CBU allows PowerHA licenses
entitlement fail-over from the registered
production server
– Minimum 1 entitlement required on
the CBU box
– CBU server allows the temporary
transfer of entitlements from primary
server for non concurrent usage on
the CBU server
– Round-up when using partial
processors
– 3.5 processors = 4 entitlements
Example
 No HA/DR required for Partition 1
– No PowerHA licenses
 HA required for Partition 2 and 3
– All processors in the production
server partitions 2 and 3 are
licensed for PowerHA
– One key, 8 entitlements
– The license key will be a permanent
key installed on partition 2 and 3
 A single processor is licensed on the
CBU server
– One key, one entitlement
– The license key will be a temporary
key for 8 cores good for two years
24
installed on partitions 2 and 3
Production
CBU
Partition #1
Unused
Partition #2
Active standby
CBU Cores
Partition #3
Active standby
CBU Cores
IBM i, 5250, PowerHA
© 2012 IBM Corporation
Key Solutions Comparison Characteristics
1. Primary use
8. Number of Backup systems
2. Characteristic of Replication
Mechanism
9. Number of Data copies allowed
3. Recovery Time
4. Recovery Point
5. Ordering of changes
6. Concurrent access
10. Cost Factors
11. End User
12. Outage coverage
13. Cluster controlled resource
14. Risks
7. Geographic dispersion
Consider other decision factors
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© 2012 IBM Corporation
Applicability of Solution to Problem Set
Start to determine possible matches of technologies to specific needs
1. Initial analysis to eliminate technologies that do not fit
2. After initial analysis, perform detailed analysis of complete requirement sets against
specific characteristics of each technology
Data Resilience Technologies
Business Continuity
Requirement
Logical
replication
Backup Window
Reduction
Switched disk
PowerHA PowerHA with
Copy Services
toolkit
n/a
Planned
Maintenance
Recovery for
disaster outage
n/a
HA for unplanned
outage
Workload
Balancing
26
n/a
n/a
n/a
© 2012 IBM Corporation
Conclusions
 When to consider Logical Replication?
–
–
–
–
–
–
Need two or more copies of the data
Want some level of concurrent access to second data copy
Need backup window reduction
Already have solution deployed using logical object replication
Need a solution that has no special hardware configuration requirements
Transaction level integrity is important for all journaled objects
 When to consider Switchable IASPs ?
–
–
–
–
–
–
–
–
27
Single copy of data meets requirements; addressed exposure to disk subsys failures
Need a very simple, low cost, low maintenance solution
No need for DR solution
Source and target system will be at the same site
Want consistent fail/switchover times within minutes independent of transaction volumes
Need transaction level integrity for all objects; no loss of in-flight data
Need highest throughput environment
Need multiple, independent databases that can be moved between systems
© 2012 IBM Corporation
Conclusions (2)
 When to consider PowerHA System Mirror (Cross-Site Mirroring) ?
– Want a system-generated second copy of the data (at an IASP level)
– Need two copies of data, but do not need concurrent access to second copy
– Want relatively low cost, low maintenance solution, but also need disaster
recovery
– Want consistent fail/switchover times within minutes independent of transaction
volumes
 When to consider PowerHA Metro/Global Mirror with IASP and Toolkit ?
– Want storage based solution for HA; especially if multiple platforms are involved
– Want consistent fail/switchover times within minutes independent of transaction
volumes
– Need two copies of data, but do not need concurrent access to second copy
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© 2012 IBM Corporation
Conclusions (3)
 When to consider a combination solution?
– When no single solution meets all of your business
continuity requirements
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© 2012 IBM Corporation
Power Systems
30
© 2012 IBM Corporation
Summary:




Clustering PLUS
Data replication PLUS
Cluster enabled replication
EQUALS ’real’ HA
Application
Resiliency
Data
Resiliency
Replication
and
Switched
IASPs
Cluster
Management
iSeries Navigator
or partner products
High
availability
cluster
enabled
applications
APIs
Cluster Resource Services
Base IBM i cluster functions from IBM
Data Replication alone is not sufficient for
HA
Clustering, Automation and application
resiliency completes the equation
31





Heart beating
IP Address Takeover
Reliable internal cluster communications
Switchover administration
Distributed activities
© 2012 IBM Corporation
PowerHA Webcast V1.0
PowerHA for IBM i Resources





PowerHA Website
– www.ibm.com/systems/power/software/availability/
PowerHA Options for IBM i - Introduction (incl. 7.1)
– http://www-03.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/PRS4021
PowerHA and DS8000 Storage Integration on IBM i
–
http://www-03.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/PRS4361
Lab Services
– http://www-03.ibm.com/systems/services/labservices
Redbooks at www.redbooks.ibm.com
– PowerHA SystemMirror for IBM i Cook book - SG24-7994 (Jan 2012)




35
– Implementing PowerHA for IBM i - SG24-7405-00 (Nov 2008)
– Clustering and IASPs for Higher Availability - SG24-5194-01
– Independent ASPs: A Guide to Moving Applications to IASPs - SG24-6802-00
– Independent ASP Performance Study on the IBM iSeries - REDP-3771-00
– Implementing SAP Applications on the IBM System i with IBM i5/OS - SG24-7166-00
IBM System Storage Solutions for IBM i
– Course code: AS930, Duration: 4.0 days
– www-304.ibm.com/jct03001c/services/learning/ites.wss/us/en?pageType=course_description&courseCode=AS930
Is your ISV solution registered as ready for PowerHA?
– http://www-304.ibm.com/isv/tech/validation/power/index.html
High Availability Clusters (Power HA) and Independent Disk Pools for IBM i
– Course code: AS541,OS830 Duration: 4.0 days
– www-304.ibm.com/jct03001c/services/learning/ites.wss/us/en?pageType=course_description&courseCode=AS541
Risk Self Assessment:
– www.ibm.com/smarterplanet/us/en/business_resilience_management/overview/index.html?re=2brf24
© Copyright IBM Corporation 2011
© 2012 IBM Corporation
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