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Re: rsync and ls -lR slow for directories with many files


On 2020/01/08 08:43, Frank-Ulrich Sommer wrote:
but rsync did not get faster.

I'm sorry to admit that the ultimate solution does not use Cygwin any more. I'm now using a Windows share and connect to that share from my Linux server with cifs and autofs. rsync then runs on the linux machine and accesses that share (due to --whole-file this should not cause problems).

rsync without any changed files directly after booting both systems (both caches are empty) now takes 91s instead of 42m.
---
I won't go into the many reasons I know of (which are very incomplete compared
to those who actually created cygwin), but in situations like you describe,
I almost never use rsync unless I don't care about time and desperately need a
feature it has.  Instead I'll find it's faster to create an uncompressed tar
on windows, copy it to linux and expand it there to work locally with it.

Any compression/signing/encrypting of data will slow down data transfer on
my home network where max CIFS transfer speeds are in the 300-700MB/s range.




Am 5. Januar 2020 22:22:35 MEZ schrieb Stephen John Smoogen <smooge@gmail.com>:
On Sat, 4 Jan 2020 at 17:16, <muell@plutonium24.de> wrote:
I am running rsync on a small linux server to synchronize files in
one directory and its subdirectories from Windows (using sshd from
Cygwin) to this server for backup purposes. The directory contains
almost 1 TB of images and videos in about 160k files on a slow disk
(Seagate Archive 8TB with SMR) with NTFS.

I am not sure if the Linux box has the slow disk or the Windows box
has the slow disk.

Even if there are no changes and whith whole file transfers rsync
takes about 45 minutes to come to this conclusion.
I am using the following command line on the linux server:

rsync -avx --stats --whole-file --no-perms --no-owner --no-group
<user>@<server>:<source directory> <local destination directory>
As rsync was only transferring a small number of bytes and gave no
clue to the cause for being so slow and as rsync should only need
filenames, dates and sizes I did a "ls -lR|wc" on both systems. On the
linux server this took about 1 minute (only slightly faster magnetic
disk, empty read cache at start) and doing the same on cygwin took
almost as long as rsync (over 40 minutes). Using Windows Explorer
(after a reboot to guarantee that the cache is empty) to get the total
number of files and the total size took only a few seconds. Reading all
file sizes with Treesize also took less than one minute. As ls -lR
needs the same information I would have expected it to take the same
time.


I would add a bunch of verbose to the rsync to see what it is doing.
(I don't recommend sending that to the list as it will be a lot of
data.. but maybe an excerpt) I am expecting it is spending a lot of
time getting the metadata off of one of the disks and mapping it to
Unix permissions then comparing if those items are the same on the
other side. Each one of those is going to be a separate action which
on a slow drive may be a spinup/get-data/spindown cycle to make it
even slower.

I would then check to see if perms and metadata on that directory
'look sane' (this is highly dependent on your environment.. if you
have an AD server giving out perms it will look different from other
things.) If the lookups for mapping metadata permissions is having to
ping an AD server or some sort of other network lookup that is going
to also slow down things.

Sorry I don't have any 'fixes'. I have always found large rsync
between Windows and Unix to be slow.

Runnin "ls -lR" a second time on Cygwin is fast as lightning as it
only takes less than 30s.
Is there any way to get ls -lR or better rsync as fast as listing the
directory with Windows tools?
Frank

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