RE: Limits to number of files opened by remote hosts over NFSv4?

["Frank Filz" <ffilzlnx@mindspring.com>]

Any server is likely to have some limit based on the memory use for the open state.

We recently introduced a configuration to limit the number of opens per clientid in nfs-ganesha for comparison, prior to that it was not specifically limited (and the configuration defaults to no limit) other than we would eventually run out of memory.

It's probably good to have a limit, but your case suggests a value in that limit being configurable.

Frank

> -----Original Message-----
> From: Brian Cowan [mailto:brian.cowan@hcl-software.com]
> Sent: Tuesday, July 23, 2024 7:16 AM
> To: linux-nfs@vger.kernel.org
> Subject: Limits to number of files opened by remote hosts over NFSv4?
> 
> I am responsible for supporting an application that opens LOTS of files over NFS
> from a given host, and potentially a few files/host from a LOT of clients. We've
> run into some "interesting" limitations from other OS's when it comes to
> NFSv4...
> 
> Solaris, for example, "only" allows 10K or so files per NFS export to be opened
> over NFSv4. When you have 2500+ client hosts opening files over NFSv4, the
> Solaris NFS server stops responding to "open" requests until an entry in its state
> table is freed up by a file close. Which causes single threaded client processes
> trying to open said files to hang... Luckily we convinced that customer to move
> the clients back to using NFSv3 since they didn't need the additional features of
> V4.
> 
> We're also seeing a potential issue with NetApp filers where opening too many
> files from a single host seems to have issues. We're being told that DataOnTAP
> has a per-client-host limit on the number of files in the Openstate pool (and not
> being told what that limit is...) I say "potential" since the only report is from
> things falling apart after moving from AIX 7.2 to 7.3 (meaning there is a non-
> zero chance that this is actually an AIX NFS issue). In this case, NFSv3 is not an
> option since NFSv4 ACLs are required...
> 
> Anyway, as a result, I'm trying to find out if the Linux NFSv4 server has a limit on
> either total number of files, total number of files per export, or total files per
> host.