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BE 12.5 sometimes needs second tape, sometimes not

Created: 20 Dec 2013 • Updated: 14 Jan 2014 | 13 comments
This issue has been solved. See solution.

I back up a couple of servers using BE 12.5 onto an HP LTO3 drive

I have just one job defined that runs in the night Monday to Friday.

Recently the job has started to require a second tape to complete the backup, almost always on Wednesday and Thursday. The job run fine on the other weekdays and doesn't require a second tape. This week on Monday the job backed up 410GB on one tape but on Wednedsay it was asking for a new tape after only 215GB and finally finished the job on two tapes with a total of only 310GB.

What I don't understand is that it's just one job repeating every 24 hours so the setup is always the same. I've even erased the tapes and used new tapes for the Wednesday and Thursday backups but I the job always wants a second tape on these days, even though it never gets near the native capacity of the tapes.

Anyone got any ideas what might be causing this strange behavior?

Thanks in advance

Operating Systems:

Comments 13 CommentsJump to latest comment

Colin Weaver's picture

Are you appending to the tape or overwriting as if appending eventually it will ask for a second tape in one of your jobs.

CraigV's picture

Hi,

Check the compression on those tapes giving you the poor compression...see if they have Hard Write Errors, as these could also be a cause of the data not being written correctly.

Thanks!

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Dannygodofbrokencomputers's picture

@Craig.

I will check the compression but I don't think that this is the issue as I have also had the problem with brand new tapes

Thanks

Larry Fine's picture

Assuming that the tapes are showing up in BE as "media full", but the bytes used is lower than you expect, then I suspect that this is another case of a clogged tape head.  Maybe it is intermittently clogging for now, which would explain why it works good on some nights.

This is a tough thing to diagnose as no errors are reported to BE.

This technote should help get you started, but you will probably have to work with the hardware vendor.

http://www.symantec.com/docs/TECH193200

Tapes report full before their Native Capacity is reached

If you find this is a solution for the thread, please mark it as such.

SOLUTION
Dannygodofbrokencomputers's picture

Still no real luck with this one.

I have cleaned the tape head but no change. Yesterday's backup asked for another tape after just over 200GB and finished the backup on the second tape after writing another 115GB onto the second tape. So, two tapes for 315GB....

The tapes in question showed 1:1 compression (compressions is enabled) but no hard write errors. The tape statistics show 314,6GB from 390,9GB used.

Like I said, I only use one repeating job but it's always Wednesday and Thursday that refuse to work properly. Does BE have any other configuration that might add some maintenance/management tasks on these days that I don't see in the job.

Otherwise I really can't explain why this is happening

Thanks

Larry Fine's picture

Yesterday's backup asked for another tape after just over 200GB

Does that tape show a status in BE as "media full"?  Is that an LTO3 media?   If yes to both questions, then I suspect that you have a clogged tape head.

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Moe Howard's picture

Experience tells me this is a drive issue, as Larry Fine has pointed out in his initial post. You can clean the heads of the drive unitl the cows come home but that won't gurantee to free tape heads which are clogged.

When heads are clogged, HP LTO drives will still back up the data but in a degraded mode...such as lower capacity, slower performance, or lower/no hardware compression. Eventually the drive will reach it's internal thresholds and toss a Tape Alert(s) and that's when you could find yourself unable to backup or restore your data.

Nip this in the bud now and have that drive replaced before it's too late.

BTW: Here's a post from an NBU customer back in 2008 who had the same problem and resolved it when the drive was replaced:

https://www-secure.symantec.com/connect/forums/lto...

SOLUTION
Dannygodofbrokencomputers's picture

Well, thanks for all the tips and suggestions. I will bow to experience and have already ordered a replacement LTO5 drive so I think that my space problems will soon be a thing of the past.

Maybe if I have a rainy day I'll take the old drive apart and see what clogged drive heads look like.

It still bugs me that this problem is not more random. It always happens on Wednesdays, regardless of which tape I use.

Thanks again for all your help

Danny

CraigV's picture

...just post back with an update if this happens again with the new drive.

Thanks!

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Larry Fine's picture

Glad I could help!

If you find this is a solution for the thread, please mark it as such.

CraigV's picture

...I've asked an admin to split this...simple to have done so wink

That's all you need to do if you feel that you should have a split solution, or if a solution has been incorrectly marked.

Thanks!

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CraigV's picture

Hi Larry,

I PM'd Amy Johnson for you asking her to split the solution between you and Moe Howard...glad I could help, and this should reflect now.

Thanks!

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