Linux NFS
Internal
Concepts
Locking Considerations
NFSv3 does not time out the lock held by a process that crashes. NFSv4 locks time out in the same situation.
Root Squash
Root squash represents reduction of the access rights for the remote superuser (root) when using identity authentication (local user is the same as remote user). If using root squash, the remote user is no longer super user on the NFS server. After implementing the root squash, the authorized superuser performs restricted actions after logging into an NFS server directly and not just by mounting the exported NFS folder.
NFS Caching
The nfs client mount option “ac” causes the client to cache file attributes. “ac” is the default as well. Changing it to not cache attributes “noac” incurs a significant performance penalty. The max time, by default that the nfs client caches file or directory attributes is 30 sec min, and 60 sec maximum, by default.