Exalogic: Applying Deferred Updates to the ZFS Storage Appliance (Doc ID 2143412.1)

Last updated on NOVEMBER 14, 2022

Applies to:

Goal

This document provides guidance on applying deferred updates to the ZFS Storage Appliance on Exalogic.

The ZFS software update may include new firmware or updates to external resources. In general, these updates are backwards compatible and are applied upon upgrade without explicit user intervention. But at times, the ZFS software upgrade may include non-reversible “deferred” updates. These involve updating a resource external to the system software in a way that is incompatible with older ZFS software releases. Once such updates are applied, it will no longer be possible to reliably roll back to previous versions. For this reason, an option is provided to apply these automatically during upgrade or to apply them post upgrade.

Deferred updates are not applied as part of Exalogic Patch Set Updates for the following two reasons:

1. To enable rollback in the unlikely event that the PSU upgrade runs into critical issues that cannot be resolved by implementing fixes or workarounds.
   
   
2. Deferred updates are not required for core Exalogic functionality

Customers may want to apply deferred updates on Exalogic for the following reasons:

1. Replication is configured to an external target ZFS appliance where deferred updates have been applied. This will require deferred updates to be applied on the Exalogic side as well, to bring the source and target pools to the same version. Refer to the following MOS note for details:
     
   <Note 1958039.1>: Oracle ZFS Storage Appliance: Remote Replication Compatibility
   
   
2. Certain deferred updates may provide benefits to their deployment
   
   
3. The upgraded version is stable and therefore, rollback is not required

For these reasons, Exalogic customers may apply deferred updates on the storage appliance as required. It is recommended that deferred updates be applied only after ensuring that the upgraded environment is stable and running for several days without problems. 

Solution

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