How To
Summary
IBM FlashSystem A9000/R highly-available architecture protects systems during their non-disruptive code upgrade (hot upgrade).
A9000/R customers using the native A9000/R HyperSwap functionality are further protected from complete system failures during hot upgrade, since HyperSwap’s active-active topology ensures that data access continues smoothly with the peer system/s, in the unlikely event that the upgraded system fails.
The following best practice leverages the fact that a hot upgrade is planned and scheduled ahead of time to manually fail over from the upgraded system before the hot upgrade, and fail back to it after the hot upgrade.
Objective
The suggested best practice has advantages and drawbacks
IBM recommends this best practice, assuming that in most cases, the advantages will outweigh the drawbacks. Either way, HyperSwap will maintain continuous data access for the protected volumes.
The advantages are:
- Hosts protected by HyperSwap will not experience a short burst of a very high latency (seconds vs milliseconds) that may occur during automatic HyperSwap failover, if the upgraded system indeed fails. Note that a manual failover does not generate such a burst.
- Hosts protected by HyperSwap will not experience a short burst of a very high latency (seconds vs milliseconds) that may occur during hot upgrade.
- Failing back from a planned failover (i.e. switch role) is simpler to operate than failing back from automatic failover.
The drawbacks are:
- Hosts at the same site as the upgraded system are likely to experience an incrementally heightened latency, as long as the primary volumes are remote.
- Some effort: Manual failover and failback operations before and after the hot upgrade.
Steps
- Before upgrading systems with code level that is below 12.3.0, the HyperSwap relations must be deactivated and reactivate after the upgrade is completed.
If the system is on 12.3.0 code level or higher, the deactivation and the reactivate of the HyperSwap relations is not required. In such case, please follow step #2.
- These are the recommended steps to perform hot upgrade from 12.3.0 or higher and according to the suggested best practice:
Additional Information
For switch role instructions, see 'IBM HyperSwap for IBM FlashSystem A9000 and A9000R' Redbook. IBM Redpaper™ publication gives a broad understanding of the architecture, design, and implementation of HyperSwap. It also discusses and illustrates various use cases pertaining to the use and functionality of HyperSwap.
See also 'IBM HyperSwap for IBM FlashSystem A9000 and A9000R IBM Redpaper™' publication, which gives a broad understanding of the architecture, design, and implementation of HyperSwap. It also discusses and illustrates various use cases pertaining to the use and functionality of HyperSwap.
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Document Information
Modified date:
22 June 2022
UID
ibm10719661