[Samba] Effect of mount.cifs cache=loose on file writes

Mario Theodoridis mario.theodoridis at regify.com
Mon Sep 26 13:01:27 UTC 2022

Hello everyone,
i'm in charge of maintaining a CentOS 7 system (3.10 kernel) which runs 
an application that makes writes to a CIFS share. The nature of the data 
is such that files and folders are created, eventually deleted, but 
never modified. And there may be a second system accessing the data, but 
most of the time these act as hot stand-by systems.
It was suggested to me to use cache=loose in the mount options in order 
to enhance I/O performance.

After reading CACHE COHERENCY in MOUNT.CIFS(8), scanning for answers in 
places like:


and: http://www.ubiqx.org/cifs/index.html

as well as searching things like:

effect of cifs cache=loose on write flushing

i have not managed to find a definite answer to the question of whether 
setting cache=loose has any effect on when a write is considered committed.

I must admit that i haven't given this question any thought before this 
request came up, and always assumed that when a write comes back, it has 
been safely written to disk on the other end.

While i realize that there may be additional factors, such as raid 
controllers on the server, that come into play on this, i'm merely 
interested in finding out whether
has negative effects on data consistency regarding file writes to a CIFS 
share on the client/server level.
Or does it only affect detecting file changes as described in the man 

I would appreciate any pointers in this regard, be it as an explanation, 
or a link to docs where this is specified.

Mit Freundlichen Grüßen / Kind regards

Mario Theodoridis

regify GmbH
Römerstrasse 39 | D-78183 Hüfingen-Behla
Amtsgericht Freiburg HRB 709343
Telefon: +49 771 8978 4238

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