Rolling Back System Software; Fail-Safe Rollback - Oracle ZFS Storage Appliance Service Manual

Rolling Back System Software

The rollback procedure reverts all of the system software and all of the metadata settings of
the system back to their state just prior to applying an update. This feature is implemented by
taking a snapshot of various aspects of the system before the new update is applied, and rolling
back this snapshot to implement the rollback. The implications of rollback are as follows:
Any appliance configuration changes are reverted and lost. For example, assume you are
■
running version V, and then you upgrade to V+1, and then you change your DNS server. If
you execute a rollback, then your DNS server setting modification is effectively undone and
removed from the system permanently.
Conversely, any changes made to user data are not reverted: if you upgrade from V to V+1,
■
and clients then create directories or modify shares in any way, those changes still exist after
the rollback (as you would expect).
If the appliance is running version V, and has previous rollback targets V-1 and V-2, and
■
you revert all the way to version V-2 (thereby "skipping" V-1), then you not only are
removing the system software settings and system software for V, but also for V-1. That is,
after a rollback to V-2, it is as if updates V-1 and V never happened. However, the software
upload images for V-1 and V are saved on the system, and you can apply them again after
the rollback, if you wish, by re-executing the update.
If after applying an update, the system is back up and running, you can use either the BUI or the
CLI to initiate a rollback to one of two previously applied updates. If the system is not able to
run at all after an update, then use the fail-safe rollback procedure.

Fail-safe Rollback

Administrators can execute a fail-safe rollback of the system software from the serial console
by selecting one of the other boot menu entries, if present. Although rollback can also be
requested from the BUI or CLI, rollback is offered from the boot menu because it is possible
that rollback will be needed in scenarios where the new system software has completely failed,
i.e., has failed to even boot.
1. To rollback from the console, access the serial console as usual, and during
boot, before the ten second timeout, use the arrow key to move the menu
selection down to one of the earlier entries.
Rolling Back System Software 359