Solaris

I doubt you can use that to umount the device.

We know that during Live Update the BE and the new BE share the same swap so, in a crash situation, it could be either BE holding the swap open and preventing deletion. It seems that you have to 'back out' the crashed procedure but that's not simple.

I'm trying to get a handle on that.

This is where I'm at with my reading right now:
Getting Rid of Pesky Live Upgrade Boot Environments | Oracle Solaris Tips and Tricks Blog

Some of the directories, eg, /var/run and /tmp, look familiar.

I don't think there is any going back unfortunately. When the problem occurred we had to rename ZFS filesystems along with change their mountpoint and canmount options. Finally we had to promote the zoneroot file system. So, we ended up removing /etc/lutab, /etc/lu/ICF.*, /etc/lu/INODE.*, and /etc/lu/vtoc.*

Basically the only BE (until I recently created one for the Oct patches) on the system is the currently running one.

I've inventoried the servers today, out of 7 that had the Live Upgrade "problem", only 4 have this problem. I've asked the customer to reboot the servers which will remove that mount point and allow me to proceed.

I just feel like there must be a way without rebooting to accomplish this...

I just wanted to post a follow up. The customer rebooted the 4 servers today and the zone 'lu' swap is now gone. I can now apply the patch set. I still feel like there must have been a way to accomplish this without a reboot though. Thanks!