We are facing issues with NFS 4.1 on RHEL 7.6. We have a lot of applications on this server and GitLab is one of them and it is impacted the most.
Excessive NFS network traffic (due to a bug with NFS v4.1) causes high CPU resulting in GitLab being unable to process any requests. This is due to this Linux kernel bug that may be fixed in more recent kernels with this commit.
ERRORS: (/var/log/messages)
Jul 3 11:15:07 hostabc kernel: NFS: nfs4_reclaim_open_state: Lock reclaim failed!
GitLab documentation recommends disabling NFS server delegation but I am not sure whether this is feasible for us as the same NFS is being shared by other applications/servers.
I did some googling and read that with this feature, the server is able to delegate the management of a file to a client. Apologies in advance for sounding naive but what does this exactly mean? Why do we want the client to handle this? How will the file management be handled if we disable this? What is the impact of disabling the NFS server delegation and what is exactly going to happen if we disable this?
