NFS

Network File System (NFS) är ett filsystem som tillåter datorer att komma åt filer över ett nätverk på ungefär samma sätt som de kan komma åt filer på lokal lagring. Detta är användbart för att dela filer mellan flera servrar. Här följer generella inställningar för server och klient, de fungerar i de flesta fall.

Installation

Server

sudo apt-get update && sudo apt-get -y install nfs-kernel-server

Klient

sudo apt-get update && sudo apt-get -y install nfs-common

Konfiguration

Server

sudo mkdir /nfsroot
sudo sh -c 'echo "/nfsroot 192.168.1.16/30(rw,root_squash,subtree_check)" >> /etc/exports'
sudo exportfs -a
sudo service nfs-kernel-server start

Klient

sudo mkdir /nfsroot
sudo sh -c 'echo "192.168.1.50:/nfsroot /nfsroot nfs rw,async,hard,intr 0 0" >> /etc/fstab'
sudo mount /nfsroot

Options

Ibland kan man behöva ändra egenskaperna för NFS-share:n. T.ex. om man har problem med att program sätter lock på filer. Här tas de vanligaste alternativen upp som är bra att känna till. Det mesta görs på klientsidan.

Klient
rw: Read/write filesystem.
ro: Read-only filesystem. Remote NFS clients can’t modify the filesystem.
hard: Applications using files stored on an NFS will always wait if the server goes down. User cannot terminate the process unless the option intr is set.
soft: Applications using files stored on an NFS will wait a specified time (using the timeo option) if the server goes down, and after that, will throw an error.
intr: Allows user interruption of processes waiting on a NFS request.
timeo=<num>: For use with the soft option. Specify the timeout for an NFS request.
nolock: Disable file locks. Useful with older NFS servers.
noexec: Disable execution of binaries or scripts on an NFS share.
nosuid: Prevents users from gaining ownership of files on the NFS share.
rsize=<num>: Sets the read block data size. Defaults to 8192 on NFSv2 and NFSv3, and 32768 on NFSv4.
wsize=<num>: Sets the write block data size. Defaults to 8192 on NFSv2 and NFSv3, and 32768 on NFSv4.

Server
rw: Read/write filesystem.
ro: Force clients to connect in the read-only filesystem mode only.
no_root_squash: The root account on the client machine will have the same privilege level as the root on the server machine. This option has security implications; do not use unless you are sure you need it.
no_subtree_check: Disable file location checks on partial volume exports. This option will speed up transfers on full volume exports.
sync: Force all transfers to operate in synchronous mode, so all clients will wait until their operations are really done. This can avoid data corruption in the event of a server crash.