smashr

Q: How can you check files and folders after copy to external HD using checksums, md5 etc ?

Hello everyone,


I am about to perform a clean install of the OS from Mavericks to Sierra. As with any OS upgrade, I backed up all my data to an external hard drive through USB (I think 3.0).

  • I manually backed up everything using Command-C and Command-V
  • When asked if I wanted to replace files or folders, I said yes and choose the option "for all".
    • By the way if someone could confirm that there is no problems that can occur when replacing a folder with less stuff in it with another folder with the same stuff but including new stuff, that would be great relief. For example: replacing A(1,2) with A(1,2,3,4,5) where A is the name of the folder and 1,2...etc are files and subfolders.
  • I checked and compared the contents of all the folders copied to the external HD using Kaleidoscope, also available on the Mac App Store (http://www.kaleidoscopeapp.com/). It checks the differences between folders etc.
  • However, and this is my main interrogation: how can I be sure that the data copied to the external HD was not corrupted during the transfers. I heard that you can use checksums, hash or md5 to check a file is valid. But I don't know anything about it and I thought it was mainly to check files downloaded from the internet. However since here I copied personal documents and photos that are dear to me, over several copies that took around 1 hour every time, I would like to be absolutely sure before formatting and installing Sierra, that everything has been copied correctly. Is there a reliable app I can use to compare folders and files from my Mac with the ones copied on the external HD using checksums, md5, hash etc ?

 

Thanks a lot for the help you can provide me !

MacBook Pro (13-inch Late 2011), OS X Mavericks (10.9.4)

Posted on Sep 23, 2016 4:43 AM

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Q: How can you check files and folders after copy to external HD using checksums, md5 etc ?

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  • by smashr,

    smashr smashr Sep 23, 2016 5:20 PM in response to smashr
    Level 1 (19 points)
    Notebooks
    Sep 23, 2016 5:20 PM in response to smashr

    Anyone has any input please, maybe I posted during an empty time slot, any help is very much appreciated ! Thanks !

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Sep 23, 2016 8:05 PM in response to smashr
    Level 9 (61,130 points)
    Desktops
    Sep 23, 2016 8:05 PM in response to smashr

    You need to have a Trusted Backup. If you don't trust the one you already made, even after checking it, you need to make another backup using a different method.

  • by smashr,

    smashr smashr Sep 24, 2016 5:25 AM in response to Grant Bennet-Alder
    Level 1 (19 points)
    Notebooks
    Sep 24, 2016 5:25 AM in response to Grant Bennet-Alder

    Hi thanks for helping out. How do you create such Trusted Backup please ?

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Sep 24, 2016 9:00 AM in response to smashr
    Level 9 (61,130 points)
    Desktops
    Sep 24, 2016 9:00 AM in response to smashr

    This largely depends on YOU, and what you trust. You appeared to express great reservations about the tedious process you just completed.

     

    Time Machine has been used for many years by a lot of Users to produce a backup 'Set'.  It presents its Backups as if they were an Hourly Full Backup, allowing you to restore to the state at a particular time with extreme ease. Time Machine can be used to restore individual files or folders, subsets such as only your files (and not MacOS) and many other combinations. Using Time Machine frees you from the tedium of keeping track of and restoring parts and pieces from multiple full and incremental backups. It also frees you from having to take any time just to make Backups.

     

    Except for the 'all afternoon' Time Machine takes to make the initial full backup in the background, Time Machine works automatically, briefly, and quietly in the background, without disrupting your daily work. Time Machine, once enabled, is very much a 'Fire and Forget' solution -- and it will be there, likely not over about an hour old, when you need it. You need not set aside ANY time to manually make a Backup. No checking is needed.

     

    Many users like the Backups created by Carbon Copy Cloner, an inexpensive utility that can create accurate and if you desire, bootable copies of what is on a particular drive or your entire Mac. It has been extended to include several backup schemes, and takes only a little configuration to make it work the way you want.

     

    SuperDuper! has also been a contender for this sort of work. It does not seem to be quite as popular as Carbon Copy Cloner, but has a good reputation.