Tape Restore Gotchas

[andrew777]

Here are a few issue I've encountered when restoring from tape and the solutions - it might save you some grief!

1. Encryption
Hardware encryption will make your backup and restores 3 to 4 times faster than software encryption so it's worth using. However, if you need to restore a tape that was backed up using hardware encryption, you will need hardware encryption to restore it. On a resent Disaster Recovery test we found that we couldn't restore our tapes as Veeam was complaining that the system didn't support hardware encryption. In the end we found that encryption on the library was set to "Library Managed Mode", not "Application Managed Mode".
To get your systems to use hardware encryption:
- Make sure your library/tape drives support hardware encryption and you have the license for it (if necessary).
- Use Vendor drivers installed in non-exclusive mode.
- Set the library to "Application Managed Mode".
You can check if hardware encryption is being used in the backup statistics.

2. Block Size
Veeam will automatically select the largest block size that the tape drive/driver supports (for performance reasons). Looking at our Veeam system (under tape properties) the LTO5 tape drives had 3 different maximum values: 524288, 1048576 and 8388608. The problem with this is that if you need to take a tape from a system backed up with a block size of 1048576 and try restoring it onto a system that only supports a block size of 524288, it won't work, you won't be able to restore the tape. The solution is to set that block size to a consistent size that all the tape drives support, for example 524288.

[Dima P.]

Hi Andrew,

Good read - thanks for sharing!

Veeam will automatically select the largest block size that the tape drive/driver supports

One small note here: if you have more than one drive in the library, they might have different default block size. VBR will set the average value every device to ensure that written tapes could be restored by any drive in the library.