Just doing a simple du -h --max-depth=1 | sort -h took 71 minutes (measured by time).

I have tested disk IO with dd; write speed 135 MB/s, and read speed 6,9 GB/s. I am using this command on a folder of rsnapshot backups; total file size is 30GB, which is approximately the same of my system. If I run du -h --max-depth=1 | sort -h (with --exclude of the NTFS disk, of course) it takes around 3 seconds.

The disk is mounted in fstab as:

UUID=C6560CA5560C97F7   /media/pc/extdisk   ntfs    permissions 0   2

du result on NTFS disk with time:

101M    ./daily.4
101M    ./daily.5
102M    ./daily.1
102M    ./daily.2
102M    ./daily.6
265M    ./daily.3
29G ./daily.0
30G .

real    71m30.353s
user    0m14.399s
sys 1m55.442s

I'm guessing it is because rsnapshot creates hardlinks, and that slows down (a lot)? I just ran the same command on a normal folder and it took 7 seconds for 6GB.

  • NOt sure but almost sure that the fact ntfs is not a unix/linux file system it way less efficient when working with command such as du – Kiwy May 1 '18 at 11:20
  • Are you using the ntfs module built into the kernel or the third-party ntfs-3g? – Emmanuel Rosa Nov 25 '18 at 22:42

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