% NFS % Alick Zhao % 2012/08/25
NFS(Network File System) aims at making accessing network files behave as if accessing local files.
- RPC(Remote Procedure Call) based
- Stateless(from the server point of view)
- widely accepted in Unix world
Features:
- Improved performance
- Strong security
- A stateful protocol?
More at RFC3010.
The article Use of NFS Considered Harmful talks about a list of concerns about NFS usage.
- Time Synchronization → use NTP
- File locking: multiple clients, server/client failures
- Delayed write caching
- Read caching and file access time → Admin should be aware of NFS's behavior
- Indestructible files(.nfsXXXX)
- uid and gid numbers rather than name → sync account
- root account specially handled(might be unexpected)
- Security → Only use NFS in trusted environment.
- Seemingly unkillable process → wait for NFS timeout(several minutes)
- Timeouts on Mount/Unmount(longer reboot)
- Overlapping exports( of a same file system, can cause confusion)
- Automount confusion(the command cat can create directories)
This article also states that reasonable NFS use situations "always involve data that has a single point of update".
