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Thread: Verifying data vs backup with rsync after mdadm crisis

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    Join Date
    Feb 2008

    Verifying data vs backup with rsync after mdadm crisis

    I recently had a huge cascade mdadm raid failure, where 3 or 4 disks had to be ddrescued to other disks and then force assembled back together. Afterwards the ext4 partition wouldn't mount because of invalid group descriptors (and who knows what else). I ran fsck -y /dev/md0 and it had to fix tons of stuff in many passes. The file system is mounting now and superficially everything looks fine, but I am worried about possibly having "bits transposed" etc in random files. (is this even possible?)

    I have a backup of the array, and I was trying to run rsync (dry-runs) to compare volumes and look for non matching files. Rsync by default only checks file sizes so I am using the checksum option.

    My rsync command is like this
    rsync -avHcn /media/md1 /media/vault
    (md1 is the backup and vault is the primary)

    This returns TONS of files (maybe everything?) so I broke it down smaller

    rsync -avHc --dry-run /media/md1/Scripts /media/vault/Scripts
    sending incremental file list
    Scripts/SortFiles2 (another copy).sh
    Scripts/SortFiles2 (copy).sh
    sent 268 bytes  received 31 bytes  598.00 bytes/sec
    total size is 13350  speedup is 44.65 (DRY RUN)
    But then I run
    md5sum /media/md1/Scripts/  /media/vault/Scripts/ 
    34c72e175a02e3bafdf172a9a4465c92  /media/md1/Scripts/
    34c72e175a02e3bafdf172a9a4465c92  /media/vault/Scripts/
    also running 'cmp' on the files returns nothing, and even running the same rsync command on one particular file shows no changes

    rsync -avH --dry-run /media/md1/Scripts/  /media/vault/Scripts/ 
    sending incremental file list
    sent 57 bytes  received 12 bytes  138.00 bytes/sec
    total size is 4333  speedup is 62.80 (DRY RUN)
    Am I missing something with the rsync syntax? My understanding is that one -v should only list the files that have differences detected and would be copied in a standard non-dry-run.

    I also noticed that if I do the same rsync command with slashes at the end of the directories (to mean the contents of the directories as opposed to the directories themselves, which should really be irrelevant here as long as they are consistent)

    rsync -avHc --dry-run /media/md1/Scripts/ /media/vault/Scripts/
    sending incremental file list
    sent 234 bytes  received 12 bytes  492.00 bytes/sec
    total size is 13350  speedup is 54.27 (DRY RUN)
    I'm really confused, am I just misunderstanding the -v option in rsync? Why does it list them when comparing Scripts but not Scripts/? Is there a better tool for doing what I'm trying to do?
    Last edited by apokkalyps; June 17th, 2013 at 09:14 PM.

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