Loading ...
Sorry, an error occurred while loading the content.

Re: [solarisx86] ufsdump question

Expand Messages
  • Laurent Blume
    ... And there is absolutely no way to protect against that, except following the ufsdump(1M) man to the letter: run it on an unmounted or read-only FS, Using a
    Message 1 of 12 , Jul 8, 2009
    View Source
    • 0 Attachment
      Chris Ridd a écrit :
      > If a file's being written to while it is being backed up, the backup is
      > only going to contain some of the changes.
      >
      > Restoring such a file from backup is straightforward, but it might
      > contain only partially valid data. That's what I meant by the
      > complication :-)

      And there is absolutely no way to protect against that, except following
      the ufsdump(1M) man to the letter: run it on an unmounted or read-only FS,

      Using a snapshot won't change that, but it will avoid an issue that has
      become prevalent those last few years: the changes on a live FS between
      the beginning and the end of running ufsdump are so big, that the backup
      simply fails at the end and is unusable.

      Laurent
    • John Taylor
      ... good stuff so far. If we remember that a root disk is generally not going to have the kind of changes that would be catastropic for transient updates,
      Message 2 of 12 , Jul 8, 2009
      View Source
      • 0 Attachment
        On Wed, Jul 8, 2009 at 9:37 AM, Laurent Blume<laurent@...> wrote:
        >
        >
        > Chris Ridd a écrit :
        >
        >> If a file's being written to while it is being backed up, the backup is
        >> only going to contain some of the changes.
        >>
        >> Restoring such a file from backup is straightforward, but it might
        >> contain only partially valid data. That's what I meant by the
        >> complication :-)
        >
        > And there is absolutely no way to protect against that, except following
        > the ufsdump(1M) man to the letter: run it on an unmounted or read-only FS,
        >
        > Using a snapshot won't change that, but it will avoid an issue that has
        > become prevalent those last few years: the changes on a live FS between
        > the beginning and the end of running ufsdump are so big, that the backup
        > simply fails at the end and is unusable.
        >
        > Laurent

        good stuff so far. If we remember that a root disk is generally not going to
        have the kind of changes that would be catastropic for transient updates,
        such as would be the case with a database file, for instance, the chances
        of losing something really important with a snapshot has got to be very
        close to zero. If you changed the root password after you snapped, then
        had to recover, the old root password would be in the backup, but that's
        not catastrophic. Annoying, but not going to compromise your business.

        OTOH, if you have a production database in a file system, or some other
        kind of logging such as would be required for Sarbanes-Oxley (in the US)
        then you have to quies the database or application so you can guarantee
        there's no transients at the time of the snap. Obviously, transactional
        logs from databases help recover to a point in time, and other applications
        may need their own "transaction type logs" if you're really concerned
        about getting back to time of the "failure".

        Ben
      • Bob Hodges
        I d like to thank everyone for their expertise and advice on ufsdump and its ins, outs and complexities. Thanks for all the input, it was very valuable and
        Message 3 of 12 , Jul 8, 2009
        View Source
        • 0 Attachment
          I'd like to thank everyone for their expertise and advice on ufsdump and its ins, outs and complexities.

          Thanks for all the input, it was very valuable and helped me decide on what I wanted (and didn't want).


          [Non-text portions of this message have been removed]
        Your message has been successfully submitted and would be delivered to recipients shortly.