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Is there a way with BC or other to ongoing check a file for changes? MD5?

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  • Is there a way with BC or other to ongoing check a file for changes? MD5?

    I've always wondered when programs like shadowprotect make huge single files as a backup of an entire drive. Or a VHD... All it takes is a single bit change to make it unusable, right?

    Today I was trying to play some several hour long MP3s that I made in 2013 and 2015. They were 300MB to 700MB. A bunch of them aren't playable. I'll check oldest archives / backups I have of them but this touches on my bigger concern of backups and files in general.

    How do you (if you do it at all) check on an ongoing basis that data files on your computer are still 'intact' - pictures, video, audio will still be as they were when you created the file?

    Does BC4 allow you to compare a folder against an MD5 of that file created earlier? not comparing 2 files using their MD5s..

    and can BC create MD5s of a folders worth of data to compare weeks / months later? Or do you know another app that can do this?

    do you do any of this (checking files to make sure they are the same as when you put them on the computer's hard drive?)

    THANKS!


  • #2
    Hello,

    BC4 can create a Snapshot file in the Tools menu -> Save Snapshot. This virtual representation of the folder at that moment in time can optionally include a copy of the CRC included, which you can then compare against the real backup to see if content has changed between its own snapshot and its current self.
    Aaron P Scooter Software

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    • #3
      WoW - shows' I don't know much at all of BC and its got so many great features! Thanks.

      conceivably, is it reasonable to snapshot your data drive / big collections of home videos & pictures that shouldn't change, and you ARE backing up... and comparing the snapshot to the original data and maybe compare the snapshot to the backup data to make sure all is in sync / havent been any changes??

      How often would you do something like that?

      And another feature of BC I think.... It could do the comparison of the snapshot, original data and backup data all at once right? I saw something about BC being able to compare 3 folders at the same time?

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      • #4
        Beyond Compare doesn't support 3-way comparison (live data, snapshot, and backup drive). It supports 3-way file and folder merge, but 3-way merge is designed for source code merges, not for equal comparison of 3 items. In a 3-way merge, a common ancestor is used to help merge your version of source code with a coworker/repository copy.

        For backups using the current version of Beyond Compare, most of our customers load a 2-way comparison in the Folder Compare or sync in the Folder Sync, then use the Sync Update command to copy changes to the backup drive.

        Snapshots are useful if you want to keep a record of data state at the last backup for media that you store offsite. It's also useful for tracking changes over time, such as detecting file changes after you install or update software.

        Snapshots are also useful for sneakernet, syncing data on two systems with removable media (USB flash drive or hard drive) as intermediate storage. See the Sneakernet article on our website for details. https://www.scootersoftware.com/supp...=kb_sneakernet
        Chris K Scooter Software

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        • #5
          Thanks!

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          • #6
            So it's a 2 step process to check the snapshot against live data and backup, right? And you'd want to check both to see that the backup hasn't changd (no sense having a backup that's corrupted a bit) and you want to check the current data so it's usable and you don't backup a corrupt file?

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            • #7
              Usually the copy and check process of the newer files is one step, as it's usually "Now" when you want to copy it over and you wouldn't have an older snapshot to verify it against. After copying it over to the backup, you then create a snapshot, assuming the backup is legitimate, and use that later to compare against for the next sync at a future date. If you have periodic snapshots of the source, you could always verify the source as well against the past versions of itself, assuming at those times you didn't already copy the source over?
              Aaron P Scooter Software

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