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overwritable media not overwriting all backup sets

Created: 11 Jan 2011 • Updated: 11 Jan 2011 | 9 comments
This issue has been solved. See solution.


I have a question about the way the OPP works.

We have a backup policy D2D2T using duplicate backup sets to tape. This policy is applied to multiple selections lists per resource/server. So we have a few backup jobs and as a result multiple backup sets are stored on each tape.

My problem is that when a tape's OPP has expired the first job to access the tape overwrites as expected however this might only take up about 30% of the tape. The next few jobs will then append to this media however some of the later jobs will then fail waiting for overwritable media to be inserted.
Some of the older backup sets from the previous fortnight still remain on this tape and are not overwritten even though the OPP has expired for the tape and the date of the old backup set. There would be enough space on the tape for the failing backup job to run had this older backup set been overwritten.

If I erase the tapes before the backup everything runs fine but as this is a manual process obviously I want to avoid this.

Is there any reason or advice anyone can give me on why only some of the older backup sets remining of the tapes are not being overwritten?

My setting are as follows:

Tools>Option>Media Management - Overwrite Recyclable media contained in the targeted media set before overwriting scratch media.

and in each of the tape job options under device and media, Append to media, overwrite if no appendable media is available.

Hopefully I've explained this well, please let me know if I need to expand on anything.

Thanks in advance.

Comments 9 CommentsJump to latest comment

PCAU's picture

Hi Amol

Yes, one of my jobs (the last one to run) is too big for 1 tape and does span across. It is this job which fails.

AmolB's picture

When the job spans over multiples tapes then the tape in the drive has to be an

overwritable tape, appendable tape will not be work.

pkh's picture

If I erase the tapes before the backup everything runs fine but as this is a manual process obviously I want to avoid this.

This is one way.  The other way is to set this particular to overwrite.  rather than overwrite when there is nothing to append, but you got to make sure that the tape is overwriteable by the time the job starts.  Another way is to shorten the append period so that when this job starts, there are no appendable tape and it will overwrite the tapes.  You got to play around with the OPP and AP to get the best combination for your environment.

PCAU's picture

Actually on further thinking from what you just said pkh, the answer above might not be correct.

If I erase the media and it works, that still leaves me with the question of why this last backup set isn't being overwritten. Given that if I erase the media it's still going to span which leads be to believe the spanning is not the issue.

pkh's picture

I misread your problem and was under the impression that your jobs failed because your initial job appends to the first tape and then was unable to span, so the wrong answer.

When you erase the media, they end up in the scratch media set and are thus all overwriteable.  You actually don't have to erase them.   You can just move them to the scratch media set and they will become overwriteable.

As to why your old media is not overwritten, check the time when their OPP expires.  It should be at the start of the job, not at the end.  Remember that the OPP starts from the end of the job and not the beginning. Suppose the OPP is set to 1 day.  If your daily job is set to start at 10 p.m. and it takes an hour to complete, then the tape will be write protected until 11 p.m. the next day.  When the job runs again tomorrow at 10 p.m. the tape is still write-protected.  If the OPP is set to, say, 22 hours, then the tape can be overwritten .

PCAU's picture

thanks again, but the OPP is deifnitely not the problem, I have set it days ahead in order to try and troubleshoot this previously.

The tapes are definitely overwritable well before the job starts and it does overwrite the majority but only some of the previous backup sets remain.

PCAU's picture

OK now I know what's going on, but it's totally different to what this thread is about, so to avoid confusion I will start fresh with another.

Thanks for all the help and sorry for the confusion (however the conversations in here have helped me figgure it out)