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krono's avatar
krono
Level 3
17 years ago

Retention Period Problem

Hello,

 

We have 7 servers to backup during the night. We are using Maxell ULTRIUM LTO 2 tapes into a Scalar robot. Normaly the backup takes two tapes. But sometimes it takes 3 tapes. I don't uderstand why. We have 2 tapes for mondays, 2 for tuesdays, etc... and 4 tapes in the scratchpool. 

 

The retention period is setup on 1 week. When the backup starts, the tapes assigned for the day are maybe not available due to the retention period. At this time if none of the two tapes are available, it takes tapes into the scratchpool... 

 

So I do not understand how it is possible to have some FULL media and have 3 tapes for a backup. If it takes tapes from scratch pool, they are empty, if it takes tape from the volume pool day, it means that the retention period is over so the tape is available ( it goes into the scrath pool ) and is empty... 

 

Thanks in advance for your help

7.1.x and Earlier
Backup and Recovery
NetBackup
  • Andy_Welburn's avatar
    Andy_Welburn
    17 years ago
    krono wrote:

    How is it possible to append on a media ??? I never set this.

    This is default (only?) action. If there is ACTIVE media in the Volume Pool (i.e. space left on tape) then when a backup starts it will use that tape from the Volume Pool. If there are no ACTIVE media in the Volume Pool (i.e. FULL/no space left on tape) then when the backup starts it will assign a tape from the Scratch Pool (if one is configured). If there are no ACTIVE tapes available and a Scratch Pool is NOT configured then the backup will fail.

    krono wrote:
    I believed that there is only two possibilities. If the tape is available it takes it and overwrite everything, or the tape is not available and it take a tape from the scratch pool...

    Will only 'overwrite' everything IF all images have expired (Time Assigned column in Media/Volume Pool will be blank). Yes, if no tape available it will take a tape from Scratch.

    krono wrote:

    In which situation the policy will perform an append to media instead of an overwrite ?

    See above - will append if tape available & ACTIVE (not FULL), 'overwrite' only if ALL images have expired.

    krono wrote:

    When I perform a MediaWritten on the tape which is full, i can see old backups of more than one month !! How is it possible that the tape is full but contains old backups that are expired due to retention period ?

    What's the latest/most recent expiry of the images? Possibly newer images appended to this tape. Could be that this tape is frozen.

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  • Andy_Welburn's avatar
    Andy_Welburn
    Level 6
    17 years ago
    A very simplistic possibility :

    Say your backup window opens at 7pm Monday and your 7 servers start to get backed up.
    Each image for each server may have a different expiry time:

    Tape1 Image 1 expires at 7:01PM Mon 1st
    Tape1 Image 2 expires at 7:31PM Mon 1st
    Tape1 Image 3 expires at 7:48PM Mon 1st
    Tape1 Image 4 expires at 7:59PM Mon 1st
    Tape1 FULL
    Tape2 Image 1 expires at 8:21PM Mon 1st
    Tape2 Image 2 expires at 9:01PM Mon 1st
    Tape2 Image 3 expires at 9:32PM Mon 1st
    Tape2 ACTIVE

    So Tape 1 is FULL but will not expire & be available for backups until all images have expired i.e. at 7:59PM on the following Monday.
    Tape2 is still ACTIVE (i.e. space remaining) therefore will be available the following Monday so the next set of backups are appended to this tape:

    Tape2 Image 1 expires at 8:21PM Mon 1st
    Tape2 Image 2 expires at 9:01PM Mon 1st
    Tape2 Image 3 expires at 9:32PM Mon 1st
    Tape2 Image 4 expires at 7:05PM Mon 8th
    Tape2 Image 5 expires at 7:12PM Mon 8th
    Tape2 FULL (Tape 1 still FULL therefore use tape from SCRATCH)
    Tape3 Image 1 expires at 7:21PM Mon 8th
    Tape3 Image 2 expires at 9:01PM Mon 8th
    Tape3 Image 3 expires at 9:32PM Mon 8th
    Tape3 Image 4 expires at 9:32PM Mon 8th
    Tape3 Image 5 expires at 9:32PM Mon 8th
    Tape3 FULL
    At this point all the images on Tape1 could have expired & therefore be available for the next backup images.

    You could check on the 'Images on Tape' report to see what images are on each tape & when they expire.
    There is also the 'Tape Lists' report which will show when the tape expires.

    This may prove or totally disprove the above !!!!!
  • krono's avatar
    krono
    Level 3
    17 years ago

    Yes, every policy backup star at 00:00 on Monday ... so when it finish, the retention time is up to  7 days... so the tape won't be available for the next Monday because it star at 00:00. Ok I understand, but in this case, the system should take a tape from the scratch pool. How is it possible to append on a media ??? I never set this. 

     

    I believed that there is only two possibilities. If the tape is available it takes it and overwrite everything, or the tape is not available and it take a tape from the scratch pool... 

     

    In which situation the policy will perform an append to media instead of an overwrite ?

     

    When I perform a MediaWritten on the tape which is full, i can see old backups of more than one month !! How is it possible that the tape is full but contains old backups that are expired due to retention period ?

  • Andy_Welburn's avatar
    Andy_Welburn
    Level 6
    17 years ago
    krono wrote:

    How is it possible to append on a media ??? I never set this.

    This is default (only?) action. If there is ACTIVE media in the Volume Pool (i.e. space left on tape) then when a backup starts it will use that tape from the Volume Pool. If there are no ACTIVE media in the Volume Pool (i.e. FULL/no space left on tape) then when the backup starts it will assign a tape from the Scratch Pool (if one is configured). If there are no ACTIVE tapes available and a Scratch Pool is NOT configured then the backup will fail.

    krono wrote:
    I believed that there is only two possibilities. If the tape is available it takes it and overwrite everything, or the tape is not available and it take a tape from the scratch pool...

    Will only 'overwrite' everything IF all images have expired (Time Assigned column in Media/Volume Pool will be blank). Yes, if no tape available it will take a tape from Scratch.

    krono wrote:

    In which situation the policy will perform an append to media instead of an overwrite ?

    See above - will append if tape available & ACTIVE (not FULL), 'overwrite' only if ALL images have expired.

    krono wrote:

    When I perform a MediaWritten on the tape which is full, i can see old backups of more than one month !! How is it possible that the tape is full but contains old backups that are expired due to retention period ?

    What's the latest/most recent expiry of the images? Possibly newer images appended to this tape. Could be that this tape is frozen.

  • krono's avatar
    krono
    Level 3
    17 years ago

    Ok, i take an empty tape. The backup starts on Monday 1st at 00:00 and it writes on the tape. When all the backups have finished, this tape is not full but the retention period is up to 7 days so eg Monday 8 at 4:00 am ...

     

    When the backups of Monday 8 will start at 00:00, will it take this tape to write on it because it is not full ??

  • Andy_Welburn's avatar
    Andy_Welburn
    Level 6
    17 years ago

    Yep.

     

    The next backups will then be appended to this tape & so it will not expire until the following week (presuming that it is full at this point!).

  • krono's avatar
    krono
    Level 3
    17 years ago

    Thank you very much for your explanations Andy.

     

    An other little question... When the expiration period is over ( retention period ), does the tape will go automaticaly in the scratch pool ? And this tape is so considered as empty ?

     

     

  • Andy_Welburn's avatar
    Andy_Welburn
    Level 6
    17 years ago

    That depends on where it was originally (I think).

     

    I believe that, if you manually reassign a tape from scratch (or wherever) into a particular Volume Pool, then when all the images on it subsequently expire it will remain within that Volume Pool to be available for the next round of backups that use that particular pool.

     

    If NetBackup reassigns a tape from the Scratch Pool during the course of a backup, then when all the images on it subsequently expire it will be re-assigned back to the Scratch Pool to be available for any future backup.

     

     

  • krono's avatar
    krono
    Level 3
    17 years ago

    last one:

     

    is it possible to define a retention period less than 1 week... eg 7 days and 12 hours ? 

     

    :-)

  • Andy_Welburn's avatar
    Andy_Welburn
    Level 6
    17 years ago

    How long are your weeks? :smileywink:

     

    Within Admin Console under Host Properties/Master Server/<master server>/Retention Periods there are 25 different retention periods available. It looks like these can be amended to suit your requirements down to days & hours altho' this is not something we've tried - it can have an impact if you change one you already use so you could try another 'unused' one - check out the Admin Guide.

     

    Also, be aware that unless you stipulate otherwise (& I wouldn't!) NetBackup will NOT mix different retention periods on a single tape. 

    Message Edited by Andy Welburn on 07-18-2008 04:05 PM
  • krono's avatar
    krono
    Level 3
    16 years ago

    We have tapes for every day of the week. So we want to keep datas for one week so we setup one week of retention. But because of the retetion period starts at the end of the backup, eg 4 hours latter, when the backup starts the next week at 00:00, it perform an append because of the retention period of one week put the tape in the scratch pool only at 4:00 am...

     

    I would to avoid append-write on the media...