none
DPM 2010 - tape backups RRS feed

  • Question

  • Hello, 

    I’m very new to DPM, and have previously used Netbackup and backup exec, so please bear with me. 
    At the moment I'm playing around with how DPM uses tapes.

    I have one DPM server with a single small disk pool.  The same server has an LTO4 drive tape library attached.  Tape co-location is not currently enabled.
    I just set-up a protection group which is configured to backup a small amount of data on one server (no more than a couple of GB).   I selected the short term to tape and full and incremental backup.  Two bran new tapes were put in the library.

    When I manually ran the job, DPM used one of the tapes.  I ran the same job again and this time it used the second tape.  However, when I ran the job again it requested a tape and did not append to any of the tapes.  Why didn't it append?

    I have some questions about the following technet document too

    When tape co-location is enabled, a tape on to which offsite backup is written will not be shown as Offsite Ready unless one of the following conditions are met: 
    a. The tape is full.
    b. One of the datasets has expired.
    c. Write-period ratio has been crossed. (By default, this is first backup time + 15 per cent of retention range.)
    Additional note: If the customer manually triggers two individual “create recovery point (tape)” actions for two protection group members that have the same long term recovery goal, DPM backup jobs will use a single tape. This is one way to check if tape co-location is working properly.

    What does it mean when one of the datasets has expired?  Does this mean the copy on disk?

    Long-Term Tape Protection (Without tape co-location enabled)
    A tape will be allocated for each full backup job and marked offsite ready immediately. The reason long-term full tape backups are on separate tapes is because they are meant to be stored offline, and possibly offsite. So each long-term backup recovery point created will always be on a new tape

    So, when co-location is turned off, does the above mean each protection group uses its own tape, or does it mean that each backup job in the same protection group uses its own tape?

    If tape co-location is turned on, will protection groups with the same retention goals set be able to use the same tape?

    Thanks loads


    Wednesday, November 21, 2012 10:01 PM

Answers

  • Hi,

    When I manually ran the job, DPM used one of the tapes.  I ran the same job again and this time it used the second tape.  However, when I ran the job again it requested a tape and did not append to any of the tapes.  Why didn't it append?

    ANS: It will not append because without tape colocation enabled, every backup is considered full. Once the backup is complete, the tape is considered to be full and is marked off site ready.

    What does it mean when one of the datasets has expired?  Does this mean the copy on disk?

    ANS: When we say that a dataset has expired, it means that the backup which was taken on Tape has expired. This is decided by considering the retention range specidied while setting up the backup to tape. For ex: While setting up the backup, we chose the retention range to be 4 weeks. So if the first backup to tape was taken on the 1st of Oct 2012 (Monday) then the same will be valid till 28th of Oct 2012 (Sunday). It will expire at Midnight when the date changes to 29th Oct 2012.

    "So, when co-location is turned off, does the above mean each protection group uses its own tape, or does it mean that each backup job in the same protection group uses its own tape?"

    ANS : Well this will depend on how the backup was taken :

    1) When we run a backup of the entire Protection Group then the tape will be considered as Full and will be marked as Off Site Ready at the completion of the backup.

    2) Incase, we decide to backup just a datasource within the Protection Group and nothing else then the tape will not be marked as off site ready till the time the following settings have not exceeded :

    TapeWritePeriodRatio - Indicates the number of days for which data can be written on to a tape as a fraction between 0 and 1. The default value is 0.15.

    TapeExpiryTolerance - Indicates the time window within which the expiry date of the dataset to be written to the tape must fall.  It is expressed as a percentage. The default value is 17 percent.

    "If tape co-location is turned on, will protection groups with the same retention goals set be able to use the same tape?"

    ANS: Yes, once enabled tape colocation gives us the ability to backup more on the same tape only for Protection Groups which have the same retention range. However, there are a few restrictions as well :

    The following restrictions apply to using data co-location in DPM:
    You cannot apply co-location selectively. If enabled, it applies to all protection groups.

    Only protection groups with the same retention period can be co-located on the same tape.

    Encrypted and non-encrypted datasets cannot be co-located on the same tape.

    Datasets from short-term backup to tape and long-term backup to tape cannot be collocated.

    Please let me know if you need any further clarification.


    Regards, AJ (MSFT)

    • Proposed as answer by ANUJ_MSFT Wednesday, November 28, 2012 8:42 PM
    • Marked as answer by PM-12 Tuesday, February 5, 2013 3:47 PM
    Saturday, November 24, 2012 12:00 AM

All replies

  • Hi,

    When I manually ran the job, DPM used one of the tapes.  I ran the same job again and this time it used the second tape.  However, when I ran the job again it requested a tape and did not append to any of the tapes.  Why didn't it append?

    ANS: It will not append because without tape colocation enabled, every backup is considered full. Once the backup is complete, the tape is considered to be full and is marked off site ready.

    What does it mean when one of the datasets has expired?  Does this mean the copy on disk?

    ANS: When we say that a dataset has expired, it means that the backup which was taken on Tape has expired. This is decided by considering the retention range specidied while setting up the backup to tape. For ex: While setting up the backup, we chose the retention range to be 4 weeks. So if the first backup to tape was taken on the 1st of Oct 2012 (Monday) then the same will be valid till 28th of Oct 2012 (Sunday). It will expire at Midnight when the date changes to 29th Oct 2012.

    "So, when co-location is turned off, does the above mean each protection group uses its own tape, or does it mean that each backup job in the same protection group uses its own tape?"

    ANS : Well this will depend on how the backup was taken :

    1) When we run a backup of the entire Protection Group then the tape will be considered as Full and will be marked as Off Site Ready at the completion of the backup.

    2) Incase, we decide to backup just a datasource within the Protection Group and nothing else then the tape will not be marked as off site ready till the time the following settings have not exceeded :

    TapeWritePeriodRatio - Indicates the number of days for which data can be written on to a tape as a fraction between 0 and 1. The default value is 0.15.

    TapeExpiryTolerance - Indicates the time window within which the expiry date of the dataset to be written to the tape must fall.  It is expressed as a percentage. The default value is 17 percent.

    "If tape co-location is turned on, will protection groups with the same retention goals set be able to use the same tape?"

    ANS: Yes, once enabled tape colocation gives us the ability to backup more on the same tape only for Protection Groups which have the same retention range. However, there are a few restrictions as well :

    The following restrictions apply to using data co-location in DPM:
    You cannot apply co-location selectively. If enabled, it applies to all protection groups.

    Only protection groups with the same retention period can be co-located on the same tape.

    Encrypted and non-encrypted datasets cannot be co-located on the same tape.

    Datasets from short-term backup to tape and long-term backup to tape cannot be collocated.

    Please let me know if you need any further clarification.


    Regards, AJ (MSFT)

    • Proposed as answer by ANUJ_MSFT Wednesday, November 28, 2012 8:42 PM
    • Marked as answer by PM-12 Tuesday, February 5, 2013 3:47 PM
    Saturday, November 24, 2012 12:00 AM
  • Fantastic response. Many thanks this reply and apologies for taking so long to respond.<o:p></o:p>


    Friday, February 8, 2013 1:29 PM
  • No worries!! Was my pleasure to be able to help :)

    Please remember to click “Mark as Answer” on the post that helps you. This posting is provided "AS IS" with no warranties. knowledge is valid only if it is shared by All. Regards, AJ (MSFT)

    Friday, February 8, 2013 3:32 PM