six demon bag

2020-05-23

Barracuda Backup Reports Missing Drive

Barracuda Backup reports show a warning when the Windows agent cannot find a drive that is supposed to be backed up:

A Volume (drive) that was previously backed up is no longer there and being backed up.: Removing volume X: because it no longer exists.

The vendor documentation has an article that describes how to bring the missing drive back online. But what if the drive was removed on purpose and people just forgot to adjust the backup configuration first? You can't simply change the backup configuration to ignore the drive after the fact, since the drive is already absent and thus cannot be de-selected.

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To fix the issue follow the procedure below:

1. Restore the drive.
2. De-select the drive in the backup config.
3. Run a backup.
4. Remove the drive.

First add the drive back. It doesn't have to be the original drive, a dummy virtual disk mounted as the same drive letter works just fine. You can do that either via diskmgmt.msc (GUI, click Action → Create VHD) or diskpart (commandline). For the latter write the following commands to a file (e.g. %TEMP%\dummy.txt):

create vdisk file=C:\dummy.vhd type=expandable maximum=500
select vdisk file=C:\dummy.vhd
attach vdisk
convert mbr
create partition primary
format fs=ntfs label=dummy quick
assign letter=X

Replace X with the drive letter of the missing drive, and change C:\dummy.vhd to a location with enough free disk space (500 MB in this example).

Run that file with diskpart:

diskpart /s "%TEMP%\dummy.txt"

That will create the virtual disk, format it, and mount it as the drive that had been removed.

Alternatively you can echo the commands directly into diskpart. In CMD that takes a rather long commandline, because all commands must be echoed into the same diskpart process to make the selections work correctly:

(echo create vdisk file=C:\dummy.vhd type=expandable maximum=500 & echo select vdisk file=C:\dummy.vhd & ...) | diskpart

In PowerShell you can use a here-string, which is both more readable and less error-prone:

@"
create vdisk file=C:\dummy.vhd type=expandable maximum=500
select vdisk file=C:\dummy.vhd
attach vdisk
convert mbr
create partition primary
format fs=ntfs label=dummy quick
assign letter=X
"@ | diskpart

Next go into your backup configuration, de-select the drive in the backup schedule(s) and save the changes. Wait until each backup that had the drive configured has run successfully at least once. After that happened you can remove the dummy drive:

@"
select vdisk file=C:\dummy.vhd
detach vdisk
"@ | diskpart
del "C:\dummy.vhd"

If the drive gets removed again before the next backup has been completed (step 3) Barracuda will not recognize that the drive has been de-selected and will keep complaining about it. This can happen for instance if someone reboots the machine, since the virtual disk mount is not persistent.

Posted 11:05 [permalink]

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