Linux – mounting nfs gives “access denied by server while mounting (null)”

debianlinuxmountnfs

I've recently upgraded one of our machines to debian Squeeze from lenny.
Previously, these machines mounted 2 NFS shares /home and /home/scans/data

After the upgrade they can only mount one at a time. If I try and mount them together I get the following error:

mount.nfs: access denied by server while mounting (null)

I also have to specify vers=3 in the fstab file or they are unable to mount at all due to the nfs server still being on Lenny.

Nothing permission wise has changed since the upgrade. There are other machines still on Lenny which still run with both shares mounted.

fstab entries for this machine:

nfs:/home /home nfs vers=3,exec,suid,nodev,nolock 0 0

nfs:/home/scans/data /home/scans/data nfs vers=3,exec,suid,nodev,nolock 0 0

Best Answer

Mmmm... so your NFS server is called nfs? I am wondering if the code parsing your fstab is interpreting that as a protocol type rather than a hostname. That would mean that the hostname would effectively be null, which agrees with what the error message says.

I would try adding an alias in your hosts file and using the alias in your fstab.

Failing that, try showmount -e nfs.

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Linux – Can’t mount NFS4 share

From what I know, NFS v4 requires all exported directories to be inside a single "root" (which has fsid=0 set in /etc/exports). For example:

/srv/nfs              xxx.xxx.1.0/24(ro,root_squash)
/srv/nfs/usr-local    xxx.xxx.1.0/24(ro,root_squash)
/srv/nfs/fea-jobs     xxx.xxx.1.0/24(rw,root_squash)

which are then mounted as:

mount -t nfs4 nat149app:/usr-local /usr/local
mount -t nfs4 nat149app:/fea-jobs /var/fea/jobs

Usually bind mounts are used to set up /srv/nfs (or /exports or similar); for example:

mount --bind /usr/local /srv/nfs/usr-local
mount --bind /var/fea/jobs /srv/nfs/fea-jobs

(for fstab, /usr/local /srv/nfs/usr-local none bind 0 0)

In your current configuration, /usr/local is being used as the NFS root (with nat149app:/usr/local being accepted only for compatibility; the real address is nat149app:/) and the server denies access to everything outside it.

See section 7 - NFS Server Name Space of RFC 3530 - NFS version 4.

Linux – automatically mounting nfs shares on debian

As suggested by @hornetbss, you probably need to delay the mounting of the nfs shares until network is up. You should be able to achieve this by adding _netdev as an option to the shares.

ip.from.the.mac:/ws_data /data nfs _netdev,rw,hard,intr,async,nodev,nosuid 0 0

There are also options fg and bg for re-trying the mounting (in foreground or background), if the first time fails.

Other possibility would be using autofs, which automatically mounts the drive when it is accessed.

Best Answer

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