[lustre-discuss] lustre-discuss Digest, Vol 235, Issue 29 strange pauses between writes, but, not everywhere

[Peter Grandi]

>>> On Tue, 28 Oct 2025 17:08:12 -0500, John Bauer via

> The application program, in my case dd, is simply doing a streaming 
> write, 8000 @ 1MB, reading from /dev/zero.  For reasons that escape me, 
> the cached memory of all OSCs, for all file systems, intermittently gets 
> dropped, causing pauses is the dd write.  The other  non-Lustre cached 
> data does not get dropped. [...]

I will have a look but some clients are running at full speed
(the MDS and OSS systems wehen mounting a Lustre instance, and
also some Ubuntu workstations on their own subnet).

I am starting to suspect some really odd LNET issue (e.g.
resonance of timeouts couple to some physical network issue, but
then the clients are on the same switch, so it is unlikely).