ISSU support 9300/9500 High performance

[osensei]

Will ISSU updates be supported on 9300 and 9500 High performance switches anytime soon?

[Reza Sharifi]

ISSU is usually supported on devices that can have dual supervisors or can run StackWise virtual (9500). The 9300 is for the access layer, and does not support ISSU.

HTH

[Leo Laohoo]

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@osensei wrote:

Will ISSU updates be supported on 9300 and 9500 High performance switches anytime soon?

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Please do not believe in the hype about ISSU, FSU/eFSU and use the normal commands.  ISSU, FSU/eFSU only works in "corner cases" and the hassle of fixing a broken ISSU, FSU/eFSU upgrade can be a humiliating, humbling and lonely drive to the site.  The good part to all this (driving to site alone) is:  No one can hear you scream (or cry).

Where I work, we call FSU as "F00k Sh1t Up".  

NOTE:  We upgraded our 9500 VSS from 16.12.4 to 17.3.4 back in October 2021.  We decided to "revisit" ISSU (to see if we had the wrong expectation).  Nope.  We were not disappointed.  ISSU crashed the Secondary unit and we had to manually go to the site and reboot.  But the Secondary unit was still running 16.12.4 and the Active was running 17.3.4.  So we had to take the Secondary offline and manually reboot it.  All-in-all, it was an eye-watering experience.

[shadrack bernard]

Not to take away from your experience, which sounds sobering; and certainly not to be a smartarse, but caveats aside, i note that the ISSU guide states that 16.12.x to 17.3.x is NOT a supported ISSU upgrade. Obviously a bit of intelligence in the process wouldn't go amiss; it wouldn't be that hard for the upgrade to gracefully quit, once the source and target versions were known to be incompatible. However, we are where we are. Perhaps this is why the process failed?

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst_standalones/b-in-service-software-upgrade-issu.html