[Samba] Performance regression of Windows clients?

Jeremy Allison jra at samba.org
Tue Oct 13 21:00:33 UTC 2020

On Mon, Oct 12, 2020 at 03:16:31PM +0200, Giuseppe Lo Presti via samba wrote:
> Hello Samba experts,
> I'd like to revive an old thread from 2017, where a performance regression
> of the Windows client implementation of SMB was discussed
> (https://lists.samba.org/archive/samba/2017-August/210366.html).
> We run a ctdb-managed cluster of Samba gateways to our distributed file
> system, and we have performed similar tests with the latest production Samba
> 4.12 release, using both Linux (cifs-utils 6.2-10) clients and Windows 10
> native clients.
> Our synthetic test simply "touches" and subsequently removes 100 files. The
> network captures show Linux clients just performing the required operations,
> including `SMB2_FILE_INTERNAL_INFO` and `SMB2_FILE_BASIC_INFO` requests
> appearing exactly 100 times each, whereas Windows clients perform in
> addition several expensive `SMB2_FIND_ID_BOTH_DIRECTORY_INFO Pattern: *`
> queries on the destination folder as well as on its parent (we counted 600+
> such requests). The latter cause a remarkable performance loss, especially
> when the storage exposed via Samba is a network file system itself.
> As the mentioned thread seems to have been moved to the samba-technical
> mailing list, was there any conclusion reached? In particular, we’re looking
> for suggestions on possible reconfigurations (if any!) of our Windows
> clients, as we don’t expect the Samba server can do anything to mitigate
> this behaviour. Or in alternative, is there an alternative SMB client for
> Windows (if it is at all possible to replace the native one)?

There is no alternate SMB client for Windows. However,
how are you driving the deletion of files on the Windows
side ?

Are you using Powershell or the file manager GUI ?

I'd guess a command line interface may do less of
the extra calls (the ultimate is to try using
the cygwin32 'rm -rf' command on a mounted drive,
as that should be as close to Linux as you can
get on Windows).

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