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Dannygodofbroke's avatar
Dannygodofbroke
Level 3
11 years ago

BE 12.5 sometimes needs second tape, sometimes not

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

12.x and Earlier
Backing Up
Backup and Recovery
Backup Exec
Troubleshooting
Windows Server (2003-2008)
  • Larry_Fine's avatar
    Larry_Fine
    11 years ago

    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

  • Moe_Howard's avatar
    Moe_Howard
    11 years ago

    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-3-tape-capacity

     

13 Replies

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  • Colin_Weaver's avatar
    Colin_Weaver
    Moderator
    11 years ago

    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 avatar
    CraigV
    Moderator
    11 years ago

    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!

  • Dannygodofbroke's avatar
    Dannygodofbroke
    Level 3
    11 years ago

    @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 avatar
    Larry_Fine
    Level 6
    11 years ago

    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

  • Dannygodofbroke's avatar
    Dannygodofbroke
    Level 3
    11 years ago

    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 avatar
    Larry_Fine
    Level 6
    11 years ago

    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.

  • Moe_Howard's avatar
    Moe_Howard
    Level 4
    11 years ago

    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-3-tape-capacity

     

  • Dannygodofbroke's avatar
    Dannygodofbroke
    Level 3
    11 years ago

    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 avatar
    CraigV
    Moderator
    11 years ago

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

    Thanks!