NFS

Network File System What is NFS? The Network File System is a file system that may be accessed via a network connection. The Network File System (NFS) was developed to allow machines to mount a disk partition on a remote machine as if it were on a local hard drive.

Cont… This allows for fast, seamless sharing of files across a network . With other file systems, the storage device must be directly attached to the local system. However, with NFS this is not a requirement, making possible a variety of different configurations, from centralized file system servers, to entirely diskless computer systems

Cont… 1. Means server keeps no state: NFS developed by Sun Microsystems Native method for file sharing between Unix/Linux systems Stateless protocol: 1. Means server keeps no state: 2. Renders server crashes `easily recoverable‘

Cont… Systems are clients, servers or both Clients import shared file systems Servers export shared file systems Servers easy to implement via network daemons Clients require kernel modifications Linux systems normally work as both already NFS is NOT Unix/Linux specific (e.g. PCNFS)

Exporting System Exporting handled by daemons .nfsd and Must be running for NFS export to work Exported file systems listed in /etc/exports, format is: hostname(flags) [hostname(flags)] Important flags: (read only) (read/write)

Cont… _squash (map all uid/gid to something) (specify user ID to map to) (specify group ID to map to) After changing /etc/exports, restart NFS killall -HUP rpc.nfsd killall -HUP mount

Viewing exports ● Use showmount: $ showmount -e $ showmount -e hostname Export list for landlord.gbdirect.co.uk: /usr/local/gbdirect/cvsroot roti.gbdirect.co.uk /home/adamg /home/andylong

Cont… Mount a remotely exported directory $ mount hostname:/share name /local/directory If successful, the export named /share name on host is mounted on our mount point /local/directory

Cont… just as if local, Remote host must be exporting the directory You must have access permission Your local mount point must exist Exactly like mounting a device