Much of the work/thoughts behind this post come from Jochen Koecher, I've just done the leg work of doing screenshots and writing stuff down in a slightly different format. The blog posts discusses a lesser-known field in the Enterprise Vault Directory Database called BackupModeRefCount. When you put a Vault Store into and out-of backup mode this field is used to keep track, as a counter of sorts.
So to get to the nuts and bolts of this ...
set-vaultstorebackupmode lots evsql VaultStore
This puts my Vault Store called lots into backup mode. You can see this in SQL:
... which whilst 'good' still leaves the Vault Store in backup mode (because the flag is greater than zero).
Of course here I've forced the situation, but when using the PowerShell scripts as part of scheduled backup routines in the evening or in the night, it is always possible that the job fails part way through, and then the following night the script will run again, and the subsequent morning will leave the Vault Stores (or some of them) still in backup mode.
There is a way out of this. There is an additional parameter (well two) that can be passed through PowerShell, as we see here:
PS C:\Program Files (x86)\Enterprise Vault> clear-vaultstorebackupmode lots evsql vaultstore -forceclearbackupmode 1
You are about to clear backup mode from vault store 'lots'. Ensure that the vault store and its partitions are not currently being backed up. Do you want to continue? [Y] Yes [N] No [S] Suspend [?] Help (default is "Y"): Y
.. that isn't too great for scripts though since it prompts you to confirm that you want to forcibly clear backup mode. And the final thing is to suppress that prompt:
PS C:\Program Files (x86)\Enterprise Vault> clear-vaultstorebackupmode lots evsql vaultstore -forceclearbackupmode 1 -SuppressConfirm
Successfully cleared backup mode from vault store 'lots'.
And then we're back to zero, instantly:
.. and that means the Vault Store is no longer in backup mode