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iforbes
Hot Shot
Hot Shot

ESXi Revert

Hi. I have to revert an ESXi cluster from 6.5 to 5.5. I'll be following the following KB:

VMware Knowledge Base

Currently, these hosts are connected to a vDS 6.5 switch. There are other ESXi clusters running 6.5 that are also connected to this vDS 6.5 switch. When I revert the cluster mentioned above to ESXi 5.5, will there be issues since they will be connected to the VDS 6.5 switch?

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daphnissov
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Immortal

Yes, you will have an issue when you revert (if it even succeeds). Also, a reversion is only possible to the *last* patch/installed version. So if you were on 5.5, then upgraded to 6.5, then installed patches, the reversion is only going back one step. As far as your vDS is concerned, I've never done a reversion after vDS is upgraded so I don't exactly know what'll happen, but what's certain is there won't be connectivity if/when it succeeds if they were connected to the same vDS prior to the upgrade.

TheBobkin
Champion
Champion

Hello iforbes​,

One can check what ESXi build version can/will be reverted to using Shift+R by looking at the contents of the altbootbank e.g. via SSH to a host:

# cat /altbootbank/boot.cfg

Note that making any updates to build or even just a single driver update will mean the altbootbank (and thus rollback option) will contain this ESXi build so unless you just upgraded to 6.5 and didn't change anything else this will potentially not be an option and re-install of 5.5 may be the only viable option.

If you think there will be issues with the vDS after rolling back you could consider temporarily setting up vSS and switching back to vDS after.

Bob

iforbes
Hot Shot
Hot Shot

Thanks guys. Looks like I got lucky and the vDS is at version 5.5. I'll have to run that command tomorrow to check the version available to revert.

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iforbes
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Are you saying that if I'm able to revert to 5.5 and the current vDS is at 5.5 I'll still have an issue (i.e. no connectivity)? I think you were saying that no connectivity if I reverted to 5.5 and the vDS is 6.5?

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daphnissov
Immortal
Immortal

I think you were saying that no connectivity if I reverted to 5.5 and the vDS is 6.5?

Yes, this is what I was saying. But heed the warning both I and TheBobkin made. Better to check at what's in altbootbank before trying a reversion.

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iforbes
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Thanks! Will do.

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