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DPM - Tape Backup copies with only one drive? RRS feed

  • Question

  • I am beginning to modify my protection groups to have long term tape protection.  I have one library and it has only one drive.  I want to have 2 copies of each recovery point sent to tape (essentially, 2 identical tape sets per frequency).  In the GUI,  I am able to specify multiple copies of a recovery point but as I read the documentation it looks like I really need more than one drive.  Is that right?

    Is there a way to do this if I only have one drive?


    Greg
    Wednesday, February 2, 2011 10:22 PM

Answers

  • Hi Greg,

    An ad-hoc copy to tape is not the same as scheduled tape backup followed by a tape copy.  It is true that all ad-hoc copy to tape jobs will require a seperate tape.

    If you had two drives, this is how DPM would handle the tape backup and tape copy jobs.

    1) The scheduled tape backup jobs get scheduled, one job for each data source in the PG. All data sources get backed up to the same tape (or may span tapes if a tape gets filled)

    2) The scheduled tape copy jobs are scheduled to start 15 minutes after the tape backup jobs. There will be one tape copy Job for each data source in the PG. No tape copy job will physically start until ALL the tape backup jobs complete.  When the tape copy jobs start, we will grap one free tape and copy the data from the backup tape to the copy tape.  After both backup and copy jobs complete, you will end up with two tapes  (copy0 and copy1) with identical data sets.

    3) During recovery, when you choose the recovery point on tape and click on the "view tape list" - it will allow you to choose which tape set (tape set 0 or tape set 1)  to restore from and give you the barcode so you can ensure the tape is in the library.

    Hope this helps you, now go shopping and spend some $$ to buy another tape drive to help the economy grow.  8-)

    Cheers.


    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Tuesday, February 8, 2011 6:19 AM

All replies

  • Hi Greg,

    Correct, you will need more than one tape drive to accomplish that goal, DPM does a tape to tape copy and thus requires multiple drives.


    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Thursday, February 3, 2011 12:54 AM
  • Thanks, Mike.  OK - I have follow up questions but first want to report my findings.  I played with copying a recovery point to tape (using recovery tab) and found what I read but I guess didn't believe until I saw it: you can only copy one datasource to a tape.  So, if a protection group has say, 3 different datasources and you want to copy a specific recovery point to tape, you need 3 tapes.  10 protection groups with average of 3 datasources each = 30 tapes.  According to what I have read, this is the same if going from tape to tape or using Copy-DPMTapeData and even if enabling tape colocation.  (Please correct me if I am wrong).

    If/when I purchase a second drive and it makes copies of my backups automatically, will the tape copies also require 1 tape per datasource?  If it uses the same number of tapes as the original dataset, is this just a "magic" procedure that can't be reproduced at any other time, though script or GUI?

    Also, will the copies automatically show up under the tape list for the Protection Group, and cataloged in the database, or are they "imported" media?


    Greg
    Monday, February 7, 2011 11:35 PM
  • Hi Greg,

    An ad-hoc copy to tape is not the same as scheduled tape backup followed by a tape copy.  It is true that all ad-hoc copy to tape jobs will require a seperate tape.

    If you had two drives, this is how DPM would handle the tape backup and tape copy jobs.

    1) The scheduled tape backup jobs get scheduled, one job for each data source in the PG. All data sources get backed up to the same tape (or may span tapes if a tape gets filled)

    2) The scheduled tape copy jobs are scheduled to start 15 minutes after the tape backup jobs. There will be one tape copy Job for each data source in the PG. No tape copy job will physically start until ALL the tape backup jobs complete.  When the tape copy jobs start, we will grap one free tape and copy the data from the backup tape to the copy tape.  After both backup and copy jobs complete, you will end up with two tapes  (copy0 and copy1) with identical data sets.

    3) During recovery, when you choose the recovery point on tape and click on the "view tape list" - it will allow you to choose which tape set (tape set 0 or tape set 1)  to restore from and give you the barcode so you can ensure the tape is in the library.

    Hope this helps you, now go shopping and spend some $$ to buy another tape drive to help the economy grow.  8-)

    Cheers.


    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Tuesday, February 8, 2011 6:19 AM
  • (Sad chuckle)  I appreciate the response, Mike.  Since I posted my question, though, it's become clear that we won't be getting a second drive.  Maybe in a few years but not now.  We have another idea and, yes, I have a follow-up question!

    Our idea for a "copy" of our quarter-end long term tape backup is to restore our quarter-end disk recovery points to another volume and then directly back that up to tape.  The "copy" would not allow for direct restore to the source but that is OK - the tapes are for archival purposes and will be kept for many years.

    My question is:  can I use Windows Disk Management to create a volume on a disk designated for DPM storage?  When I was working with Product Support Services on another issue, I seemed to get that impression but we never actually did it.  If so, I'd use this volume as the staging area for the quarter-end copy.  I'm also hoping to script the process to restore to the staging area.


    Greg
    Tuesday, February 8, 2011 4:48 PM
  • Hi Greg,

    Yes, you can manually create a volume on the same dynamic disk that is in the DPM storage pool, DPM will notice the reduced free space and not harm anything.  Just a FYI, I'm not very power shell savy, so you are on your own there <g>.


    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Tuesday, February 8, 2011 5:36 PM
  • No problem. I was thinking of using PowerShell but I forgot (until now) about the command "dpmbackup -replicas"   That and robocopy might be all I need.  I even wonder if DPM could directly back the shadowcopy folder directly to tape.
    Greg
    Wednesday, February 9, 2011 12:39 AM
  • Serious question - what happens if I want 3 copies?  Is the primary library always the same and the copy library just loads up more tapes when the first copy is done or does it do "round robin" (3rd tape set is copied from 2nd)?  Or do I need 3 drives?

    Here is why I am asking.  I had an idea over the weekend - use a virtual tape library (e.g. firestreamer) as the primary library and then my physical tape library as the copy library.   I would use the virtual tapes purely for copying to the physical tapes  - I'd need to make 2 physical copies so I'd specify 3 copies in the PG - and then script deleting the recovery points / tapes on the virtual library. That way I'd have 2 tape sets indexed to the original PG.  But, the answers to my questions above may shoot the idea down.  I could get a trial version of firestreamer, set up the jobs, and wait 24 hours to see what happens but I'm hoping someone could tell me faster than that...:)

     


    Greg
    Tuesday, February 22, 2011 6:38 PM
  • H Greg,

    The copy library specified in the PG will be used for all destination copies.  I am a little concerned about the idea of expiring the master copy RP's using the powershell script - I don't really know how that will effect the copies, or ability to restore from the copies, so I think you need to test that aspect out before jumping in with 2 feet.


    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Tuesday, February 22, 2011 7:06 PM
  • Hi Mike,

     Talking about: "2) The scheduled tape copy jobs are scheduled to start 15 minutes after the tape backup jobs."

    In my case, We use the tape copy for a monthly tapes, but this situation (the tape copy within the job) makes increase in a significant way the windows backup time.

    Is it possible to change this 15 minutes for any other period of time? Or better yet: make it in other complete different task?

    Thanks a lot, Serhu.-

    Monday, April 9, 2012 8:39 PM
  • Hi Serhu,

    <snip>
    In my case, We use the tape copy for a monthly tapes, but this situation (the tape copy within the job) makes increase in a significant way the windows backup time.
    >snip<

    Can you elaborate on this ?   Do you mean that the time to perform a tape to tape copy is significantly slower that the initial tape backup from DPM replica to tape ?    What is an typical example of the overall difference.

    Disk RP --> tape backup job took XX Minutes.
    Tape RP --> tape copy job took XX Minutes

     


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.

    Monday, April 9, 2012 9:42 PM
  • Hi Mike, Ur right; elaborating:

    . we have 2 units Ultrium on a 25 Slots library; and defined more than 5 PGs on DPM2010

    . every PG has defined differents sources, and when it's the monthly backup: have to execute the "Tape Backup" and a "Dataset copy" (to obtain copy0 and copy1, defined like second tape in the "Recovery Goal3" )

    . the times to do the "Dataset copy" task are significant respect to the "Tape backup":

    Tape backup

    04/06/2012 19:00

    0:51:56

    120,722.81 MB

    Dataset copy

    04/06/2012   19:15

    3:03:39

    120,722.81 MB

    Tape backup

    04/06/2012   19:56

    0:04:56

    3,816.94 MB

    Dataset copy

    04/06/2012   22:55

    0:10:11

    3,816.94 MB

    Thats why I'm trying to find out the way to make the "Dataset copy" it in other complete different task.

    Thanks in advance, Serhu.-

     

    Tuesday, April 10, 2012 3:06 PM