Scenario: Geographic mirroring
This scenario describes an IBM® i high-availability solution that uses geographic mirroring in a two node cluster. This solution provides both disaster recovery and high availability.
Overview
Geographic mirroring is a PowerHA® technology where
data is mirrored to a copy of the independent disk pool at the remote
location. This solution provides disaster recovery in the event of
a site-wide outage on the production system (System 1). In that situation,
failover to the backup site (System 2) occurs, where operations can
continue on the mirrored copy of the data. This solution provides
a simple and less expensive alternative to external storage-based
solutions, such as IBM System Storage® Global
Mirror and Metro Mirror. However, geographic mirroring does not offer
all the performance options that the external storage solutions provide.
Objectives
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- Provides availability for your business resources during planned outages
- Provides availability for business resources during unplanned outages
- Provides availability for business resources during a disaster
- Enables data to remains current and may not need to be synchronized
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There is no concurrent access to the disk pool. Only the production copy is normally accessed. However, you can detach the mirror copy for offline processing of a second copy of the data.
- Potentially affects performance because increased central processing unit (CPU) is required to support geographic mirroring
- Consider using redundant communication paths and adequate bandwidth
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Details
The following graphic illustrates this solution:
![Cross-site mirroring with geographic mirroring](hasm502.gif)
Configuration steps
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- Complete planning checklist for cluster
- Create a cluster
- Create a cluster administrative domain
- Start a cluster administrative domain
- Create an independent disk pool
- Add monitored resource entries
- Make the independent ASP highly available
- Configure geographic mirroring
- Vary on the independent ASP
- Perform a switchover to test your high-availability solution
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Complete the following steps to configure
the high availability technologies that are associated with this scenario
using commands:
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- Complete planning checklist for clusters
- Create a cluster
- Add nodes
- Start nodes
- Add nodes to device domain
- Create a cluster administrative domain
- Start cluster administrative domain
- Create an independent disk pool using Configure Device ASP.
- Add monitor resource entries
- Create device CRG
- Start a device CRG
- Use Vary Configuration to make the disk pool available.
- Perform a switchover to test the configuration.
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