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.
