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I don't understand one thing in continuous incrementals

Last post 07-09-2008 7:01 PM by Raenar. 4 replies.
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  • 07-08-2008 8:41 AM

    • bhiers
    • Top 500 Contributor
    • Joined on 04-08-2008
    • Posts 2

    I don't understand one thing in continuous incrementals

     If you do a continuous incremental and have the imagemanager set to 7,30,90 aren't you going to run out of room sooner or later? Or does Imagemanager update the base image so it only goes back so far? I just missing something here because it doesn't make complete since to me. I'm guessing I'm looking for a feature that I set for total disk space for the continues backup to use and after that it drops information.

  • 07-08-2008 10:58 AM In reply to

    • Doug
    • Top 10 Contributor
    • Joined on 01-30-2008
    • Posts 122

    Re: I don't understand one thing in continuous incrementals

    Any time you are continuously adding image files you will eventually run out of disk space.  However, after one year of using the 7, 30, 90 retention you may only have 9 more files than you did after the first 3 or 4 months of the chain.  Basically there is a moving window of 3 to 4 months of collapse weekly files (since weekly collapse files can only be removed as a set of files between monthly collapse files), 4 to 5 weeks of collapse daily files (they are also removed as a set between collapse weekly files) and 7 to 8 days of incremental files (also removed as a set between collapse daily files).  So, after 1 year you will only have a single file for each of the first 8 or 9 months and then the moving window of files as explained above.  These files may be large depending on the size of the original incrementals that have been collapsed, so you may need to reduce the 7, 30, 90 day retention if you do not have the space to retain this many files.

    We do not have a retention policy that adjusts files kept based on disk space remaining.

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  • 07-08-2008 9:40 PM In reply to

    Re: I don't understand one thing in continuous incrementals

    I've posted before about this, & have requested that Image Manager have more collapse options, doubt it will happen so we skip Image Manager & do it ourselves:

    CI's @ 15mins, between 8-6 M-F.

    Every weekend we collapse anything older than 28days into a new base, delete the original base & related incrementals & re-name the new base file to the original base file name.

    The backups continue fine after that.

     

    Combined with our tape schedule, we have 28days worth of Incrementals on disk, forever's worth of Increments on tape.

     

    Yes the collapse process of a new base is time consuming, but in our case it's effectively offline anyway, doesn't affect any production servers & still fits well within a normal backup window anyway. The Image Manager option in our opinion is just delaying the inevitable, eventually, you'll have to do *something* with all those files. We prefer to deal with them the way we have since Image Manager doesn't gives us the option.

  • 07-09-2008 4:18 PM In reply to

    • Doug
    • Top 10 Contributor
    • Joined on 01-30-2008
    • Posts 122

    Re: I don't understand one thing in continuous incrementals

    We look at feature requests for future versions and prioritize them based on several factors including the number of users that would benefit from a given feature.  If other users are also interested in seeing ImageManager collapse the base image forward we would like to hear from them as well.

    I want to make sure you are aware of a potential problem with the method you describe that bypasses ImageManager.  Incremental file names include a sequential numbering scheme but this does not mean each file is necessarily dependent on the previous file in the sequence.  One example where this will occur is when a DiffGen backup is created due to an interruption to incremental tracking (power failure, dirty shutdown, etc.)  If any file in the chain has gone bad the DiffGen may succeed but any file from the bad file on will not be used to create the new incremental.  When you try to manually collapse the chain based on file name it will fail.  You must manage file dependencies yourself which is one of the tasks done by ImageManager.

  • 07-09-2008 7:01 PM In reply to

    Re: I don't understand one thing in continuous incrementals

    While it isn't perfect it seems to be working for us at the moment, if we start to experience the problem stated above we'd probably have to write something that combines the output of the tools posted here: http://forum.storagecraft.com/Community/forums/p/413/1967.aspx#1967.

    So something like this: look at first file older than 28days > list files it depends on > pipe those to a collapse job > carry on as normal.

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