The Geek Diary

Solaris beginners guide to NFS

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What’s NFS

Network File System (NFS) is a protocol which allows file systems on one system to be made available on a remote system on the network. NFS works on the server-client model with server sharing the resource and client mounting it.

NFS versions

The 3 major versions of NFS are :
NFSv2 (very rarely used today. Allows maximum file size of 2GB)
NFSv3 (used in solaris 8 and 9)
NFSv4 (was introduced in solaris 10 )

All three versions utilizes a collection of RPC protocols and daemons as specified below.

Solaris Daemons RPC Service Name S10/S11 SMF service Description
rpcbind rpcbind / portmap svc:/network/rpc/bind:default RPC “portmapper”
mountd mountd svc:/network/nfs/server:default MOUNT protocol server
nfsd nfs svc:/network/nfs/server:default NFS server
lockd nlockmgr svc:/network/nfs/nlockmgr:default network lock manager (aka NLM)
statd status svc:/network/nfs/status:default RPC status monitor
nfs4cbd N/A svc:/network/nfs/cbd:default NFSv4 callback daemon
nfsmapid N/A svc:/network/nfs/mapid:default NFs4v user/group id mapping
Note : nfs4cbd and nfsmapid – solaris 10 only. Solaris 11 uses idmap daemon instead of nfsmapid.
Another service present on NFS clients is – svc:/network/nfs/client:default used to mount NFS file systems from /etc/vfstab on boot

NFS sharing

There are many different ways to share a file system or directory on remote system. Below are few basic examples of sharing a file system as NFS.

1. The general way
The general syntax for solaris 8, 9 and 10 is :

share -F nfs -o [options] [pathname]

For example : sharing /data mount point as read/write to hosts system1 and system2 only. Here rw=options is a Access control list. (IPs can be specified instead of hostnames here)

# share -F nfs -o rw=system1:system2 /data

2. Solaris 10 ZFS way
Similar example as above for solaris 10 ZFS file system would be :

# zfs set sharenfs='rw=system1:system2' datapool/data

To un-share the file system we shared :

# zfs unshare datapool/data

3. Solaris 11 ZFS way

In case of solaris 11 the syntax differs completely from solaris 10. Here we need to name the share while sharing it.

# zfs set sharenfs=on datapool/data
# zfs set share=name=datashare,path=/data,prot=nfs,rw=system1,system1 datapool/data
– The old solaris 8,9,10 way is still supported in solaris 11, but we need to add and entry to /etc/dfs/sharetab to make the NFS share persist across reboots. Remember its not dfstab in solaris 11.
– For ZFS as NFS shares we do not need to add any entry to any file as SMF services will take care of sharing it across reboots.

Mounting NFS share at NFS client

Manual Mount
To mount the NFS share manually at the NFS client, the syntax is :

mount -F nfs -o [options] [NFS_server]:[mountpoint]

For the NFS mount point to mount automatically across reboots, use the /etc/vfstab and add below entry :

#device                device          mount         FS      fsck      mount     mount
#to mount              to fsck         point         type    pass      at boot   options
192.168.10.23:/data      -             /mnt          nfs       -        yes       ro,bg,vers=3

Note the bg option in the last column. It stands for background and allow the boot process to proceed should the NFS server not be available at boot time.

Gathering info

There are many commands to get information of NFS shares.

1. share
Use the share command on NFS server to display the current shares with all the options :

# share
   -      /data    rw=system1   ""
   -      /home/john     rw=system1,system2   ""

2. showmount -e
The showmount -e command contacts the mountd daemon and lists all the shares with options.

# showmount -e

3. dfshares
The dfshare command displays the same information as showmount -e but in a different format.

#dfshares

Sharing using dfstab

The NFS shares, shared using the share command won’t persist across reboots. The solution to this is using the /etc/dfs/dfstab file. The general format of a NFS entry in dfstab file is:

share -F nfs -o rw=system1 -d "Home Dir" /export/home

After adding the entries to the dfstab we need to use the shareall command to share the entities mentioned in the dfstab

# shareall

Now, similar to shareall, to un-share all the NFS shares in one go use :

# unshareall

Now, similar to /etc/vfstab, all the NFS shares that are currently shares are listed in the /etd/dfs/sharetab file.

NFS server/client Start/Stop

Before you can start sharing NFS shares and mounting them on remote server, you must start the NFS server and NFS client.

For Solaris 8,9 :

# /etc/init.d/nfs.server start
# /etc/init.d/nfs.server stop

For Solaris 10 :

# svcadm enable svc:/network/nfs/server:default
# svcadm disable svc:/network/nfs/server:default

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