Do cloud services synchronize incremental changes within encrypted sparsebundle files?

Discussion in 'Mac Apps and Mac App Store' started by jdocdp, Jan 25, 2018.

  1. jdocdp macrumors member

    Mar 9, 2017
    From just using portable HDs as backups, I'll from now on start using Google Drive as an extra security measure.

    However, since it's increased backup security (and not portability/accessibility) I'm looking for, I'm not interested in uploading my files as they are. Not without encrypting them first, as I'd like to protect myself from hacking (and for the sake of privacy in general).

    What I'd like to do is put all my files in one encrypted disk image which would be around 100 GBs. I would go with a DMG, but if I simply modify one TXT file inside it (which takes up KBs) I wouldn't want it to upload the entire 100GB DMG file again in order to sync it.

    I recently learned about sparsebundles (haven't used it yet), so if I go with a 100GB encrypted sparsebundle instead of a DMG, would Google Drive recognize incremental modifications that occur inside it, and therefore synchronize accordingly (not the entire file each time)?

    If Google Drive doesn't, do you know of any other cloud services that do? Maybe Dropbox or something else?

    Thank you very much.
  2. chabig macrumors 603

    Sep 6, 2002
    I have several encrypted sparse bundles on cloud services. I'm only familiar with two service, iCloud and DropBox.

    - iCloud doesn't sync incremental changes. The entire image is re-uploaded after each change.
    - DropBox does sync incremental changes by only uploading the changed bands inside the bundle.

    Because of the way iCloud works, I divide my files into separate bundles and keep the size of my them less than 1GB. Larger bundles go to Dropbox.
  3. jdocdp thread starter macrumors member

    Mar 9, 2017
    There's this one question I need to ask in case you know. (I probably should've made a new thread for this but I guess it's kind of related to this one so I didn't)

    Right now, I keep my sensitive documents in an encrypted DMG, but I'll move them all in a sparsebundle instead, because apparently it saves me a lot of time due to it backing up incrementally.

    As far as the "technology" behind sparsebundles is concerned, do I have to worry about file corruption more (or less) than DMG's? Meaning, if I'm just as careful (after moving to sparsebundle from DMG), do I have a higher (or lower) risk to encounter corrupted files?

    Also, when a sparsebundle fills up with files and reaches its limit in size, is it advised to make a new one and move the files in it, or should I just run the Terminal command (if I'm not mistaken it's hdiutil compact /Volumes/*name...*/*name...*.sparsebundle) which reclaims the unused space for me?

    As you can probably already see, first and foremost, my goal is to avoid encountering corrupted files. If using a sparsebundle instead of a DMG isn't as safe, I could definitely give up the advantage of the time I save when backing up.

    Thank you.
  4. chabig macrumors 603

    Sep 6, 2002
    I don't know why would it be more at risk than any other file? As to size, make it larger than you think you'll ever need. It only takes up as much space as it requires. There were a few times mine grew to their limit, and I just made a new (larger) bundle and copied the files over.
  5. jdocdp thread starter macrumors member

    Mar 9, 2017
    Actually, I would just go ahead and make it 1 TB, but the thing is that after you delete a file inside it (and of course empty the Trash as well) its size doesn't reduce.

    I just tested it. Deleting a 5 MB mp3 from a filled 20 MB sparsebundle did not reduce its size from 20 MB to 15. It just remained 20 MB.

    Going with a 1 TB sparsebundle, and as files come and go in it, it will eventually hit its 1 TB limit while not actually containing 1 TB worth of files inside it. In the long run that's just unused space on one's HD.

    I'm not confused about something here, am I? :/
  6. jdocdp thread starter macrumors member

    Mar 9, 2017
    Oh yea I know this (I mentioned it myself when I first asked you)

    See, that's what I'm asking; any undesired results when compacting the sparsebundle with Terminal (instead of just simply creating a new sparsebundle and moving your data in it from the previous one)?

    By undesired results we could potentially refer to corrupted files (that's due to this Terminal compacting exclusively), which is what I'm afraid of the most as it usually goes by unnoticed. Have you encountered something like this in the past?

    Also, from the link you directed me to, I read this post:
    Is this true? I'm backing up to an HD directly connected to my MacBook, not over the network.[/QUOTE][/QUOTE]
  7. chabig macrumors 603

    Sep 6, 2002
    I have never contacted a sparse bundle, but I have had a few become corrupted for no apparent reason. On those occasions I’ve just retrieved my latest backup and pressed on.

    When I’ve filled one to capacity I’ve created new ones and copied files over.

    And for Time Machine—it only uses sparse bundles when the backup destination is on a networked drive. On a directly connected external drive no image is used.
  8. jdocdp thread starter macrumors member

    Mar 9, 2017
    Exactly what I was afraid of. Interesting.

    Ok, so what I need to do in order to backup a sparsebundle file on my MacBook using TM? Does it not get backed up at all? Sorry, I didn't catch this one. :/
  9. marnixva macrumors newbie

    Nov 5, 2017
    --- Post Merged, Oct 21, 2018 ---
    Is this really true for sparsebundle files? Since sparsebundle files are really a set of files with many "bands" files it doesn't make sense for icloud to copy all the "bands" files over even if only a few have changed. I'd just like to get some confirmation on this. Could it be that you are thinking of *.sparseimage files rather than *.sparsebundle files?
  10. DavidDoyle macrumors member

    Dec 11, 2013
    Have you considered Boxcrypter? Free and performs encryption on a per file basis - limiting any potential corruption to individual files. Creates encrpyted files in the cloud on the fly and use straight within Finder.

    I looked at various options for storing files and wasn’t happy with other options that used proprietary formats that hid all file details from me.

    Boxcrypter works best with something like Wasabi/S3. For iCloud it seems there is a technical limitation meaning files must be stored locally also... which is not suitable for me as I wanted to save space on local drives.

    Ps I will use Chronosync to sync files from my machines to the Boxcrypter drives, so can use for backup purposes.

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10 January 25, 2018