Disk verify error on rotating SD backup

[prestonholmes]

I use SD in a backup scheme where we do nightly smart updates, and then rotate those offsite every week in a rotation with 3 drives (one on-site, one off-site, one in transit). I have a post backup script that runs diskutil verifyvolume command on the backup and mails me the results.

I've set the UUID so everything has been pretty much just working fine.

Recently, when a drive rotates back into active nightly backup, the backup completes fine, but the verify reports minor problem in the header.

I can run diskutil repair on the volume, which works and the drive will happily backup and verify each night without error for the rest of the week, but when the new drive rotates back in, the error returns. My google research suggests that the error -9972 is a severe one, but DiskUtil reports minor error, and the system works fine for the entire remainder of the week.

SD version is 2.13 v80

Here is the relevant bits of the verify volume output:

Error detected (-9972) while verifying/repairing volume disk3s3 backup
Started verify/repair on volume disk3s3 backup
Checking HFS Plus volume.
Volume Header needs minor repair
The volume backup needs to be repaired.

The drive when offsite is just sitting in a safe box. There must be something different about the three offsite volumes that is throwing SD off?

-Preston