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  1. #1
    Join Date
    Oct 2004
    Posts
    3

    Unanswered: Does tape size matter?

    When doing a ontape backup, does the tape need to have enough storage space to cover the amount of allocated disk storage, or does it just need enough to cover the amount of data.

    I have a database with 29 GB of allocated space while the data is currently taking up 21 GB. The tapes that I have are 24 GB. I get no error when doing backups (no calls for additional tapes) but restores to another box don't seem to work.

    Backups take about 3 hours, while the restores will run for days with nothing happening. What would the expected time be for a restore?

  2. #2
    Join Date
    Nov 2004
    Posts
    26
    what version of ifmx?

  3. #3
    Join Date
    Oct 2004
    Posts
    3
    Ids 9.30 Uc3

  4. #4
    Join Date
    Nov 2004
    Posts
    26
    Quote Originally Posted by gallionf
    Ids 9.30 Uc3
    I use 7.31 which has a 2gb limit, so not relevant. I have set my tape device up on one of my instances to be a file rather than a device. I've been able to move these archives between machines and restore successfully.

    One thing I do know, total instance size is greater than 2gb and unless used space exceeds that limit I don't have any problems, even then all I have to do is rename the existing archive file and "touch" a new one.

  5. #5
    Join Date
    Jun 2004
    Location
    Madrid, Spain
    Posts
    47
    Tape size is not important. It's just an estimation on how much data will your tapes address. If your system has 29 Gb, but only 21 Gb of data, it will just save 21 Gb plus the internal structures needed (reserved pages, for instance). If you launch a level 1 backup it will save just the modified data since the last level 0 backup , and just the modified data since the last level 1 or 0 backup if you launch a level 2.

    If you use 9.40 you can specify 0 as the tape size (all that the tape can hold) and when the first tape fills it will ask you for the second one.

    I'm pretty sure that the 2Gb limit on the tape size is due to the destination of the tape (ontape had a 2Gb. limit on the size of the files it could handle, that has been overriden in 9.40)

    The problem about the restore should refer to another question: is the OS/IFX version identical in the second machine? Have you created the chunks (you don't need to create the whole system: just touch them and verify they're able to grow to the size needed). Does onstat -D show any increase in the chunk activities?

    And last: if your backup process last for 3 hours I'd expect it to last no more than 4.5-5h. Check with repeated 'onstat -D' that the job gets done.

    Hope it helps.
    José Luis Matute.

    Regards from Spain.

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