0

first question on StackExchange, so apologies if there are etiquette breaches!

I am using Robocopy to mirror a complete disk drive to an external drive for backup/archive purposes. I used the following command line: robocopy c:\ f:\BACKUP\20160607 /mir /zb /v /np /mt /r:2 /w:0 /log:f:\BACKUP\20160607.log

The top of the log file looks like this (note the altered switches):

   Source : c:\
     Dest = f:\BACKUP\20160607\

    Files : *.*

  Options : *.* /V /S /E /COPY:DAT /PURGE /MIR /ZB /NP /MT:8 /R:2 /W:0

According to Windows, the source drive has 685,361,848,320 bytes of used space So far the target drive (empty before the operation started) has 1,149,757,237,960 bytes of used space. The operation hasn't finished yet.

Why is so much more data being copied and where is it coming from? I can't find any suspicious entries in the log so far.

I did find this: https://stackoverflow.com/questions/34192978/robocopied-drive-is-inconsistent-from-source-number-of-files-match-not-disk-us

but I'm not sure explains the huge changes I'm seeing (the source drive doesn't have compression switched on). I am copying from NTFS to exFAT and the block size on the destination drive is 512Kb (I think), but I wouldn`t have thought that would give this result.

Has anyone else found this problem or what causes it. At the moment, the copy is still running and growing with no end in sight! I don't really want to waste a 2TB drive on a 600Gb mirror copy.

Improve this question
6
  • 1
    "According to Windows" How did you check this exactly? If it was via Explorer, did you have 'show hidden and system files' enabled when you checked? Perhaps use WinDirStat (as Administrator, with Show Hidden and System Files enabled) to get a more accurate data breakdown...
    – Ƭᴇcʜιᴇ007
    Jun 8, 2016 at 15:43
  • I'm running as administrator and the hidden and system files are detected and copied or skipped if in use. That's not the problem, what I want to really know is how it's possible for a 600Gb disk to produce a file copy of over 1TB? This is not physically possible, so where is all the data coming from? I'm thinking I must have some kind of recursive shortcut or something in there?
    – Handy
    Jun 8, 2016 at 18:11
  • I can't think of any reason to would do this. Wait for it to finish, then use WinDirStat (or a like) to compare them... Then once you can see what actual differences there are (and convey it to us) then perhaps it will become obvious as to why it's happening. Based on the info you've provided, there's no reason for this to happen.
    – Ƭᴇcʜιᴇ007
    Jun 8, 2016 at 18:17
  • Thanks, I'll try that. However, I had to abandon the current run as I needed to use the machine elsewhere, so had to disconnect the external drive.
    – Handy
    Jun 8, 2016 at 18:21
  • 1
    I don't recommend backing up from NTFS to FAT: not all file types are supported (especially links), and I certainly don't recommend such a huge block size, which could well account for a lot of the increased disc use. Any links in the source will probably result in duplicate files in the copy (I would expect this, but I haven't tested it), though you may eliminate some duplication if you add /xj to the options.
    – AFH
    Jun 9, 2016 at 11:49

0

Reset to default

You must log in to answer this question.

Browse other questions tagged .