DUP to tape shows less data than B2D job

[MP_DM]

Win2008R2 - BE2010R2SP1 and all Hotfixes.

I recently noticed that our DUP to tape jobs that follow our B2D jobs are not backing up the same amount of data.  Example:  Incremental B2D job backs up 40GB of flat files from our file server.  A DUP to tape job follows this B2D job, but it only writes about 6GB to tape.  Basically the job histories do not match up anywhere close.  I understand that compression will make the data on tape much smaller, but that is not the issue here.  The trouble is that BE reports that it only copied a total of 6GB to tape.

When I review the job log for the DUP to tape job, it shows only a total of 6GB is backed up.  Essentially, the expanded job log confirms that only 6GB was duplicated to tape.  All jobs report that they ran successfully.  No errors.

I have verified that the DUP job is, in fact, duplicated the backup set for the correct specified incremental B2D job.

Has anyone ever seen this before?

Thanks,

David

[pkh · Accepted solution]

If you are using compression for your backup job, then your duplicate job will show a smaller amount of data to be copied.  For example, my daily SQL database backup job reports about 16GB of data backed up, but the duplicate job of this data shows only 2GB.

If you are overwriting your .bkf files, then just check their size using Windows Explorer.  The amount of data duplicated should be close to that figure.

[MP_DM]

Thanks for the reply.  I guess that could be what is happening.  It just struck me as odd, since we have several installs of BE in our organization and that is the only one that seems to have such a large difference in job size.  I've seen a difference of 5% or so on the disk to tape, but never a factor of 6x like on this one job.

A majority of the data backed up is a flat database backup, so I guess it's very possible that file is compressing really tight when dup'ed to tape.