[mythtv-users] NFS mounts permissions

Daniel Kristjansson danielk at cuymedia.net
Sat Sep 8 16:41:03 UTC 2007

On Sun, 2007-09-09 at 01:53 +1000, Bruce Nordstrand wrote:
> I have just completed a rebuild of my combined backend/frontend into a 
> master backend only (3 cards), 1 slave backend (1 card) and 1 frontend 
> only. I seem to have an issue with the permissions on my NFS mounts on 
> the slave backend.
> This is my define in /etc/exports for the myth recordings directory on 
> the master backend:
> /myth-data,no_root_squash,async)
> The recordings are actually in a sub directory, recordings.
> I created a mount point on the slave, /myth-data and mounted the NFS 
> directory on that. The permissions on the slave directory were set to 
> mythtv:mythtv and 775. However, the slave is telling me it has no 
> permission to write to the recordings directory.
> What am I doing wrong?

Unix doesn't use the name of the account or group, it uses the 
user and group numbers. So they must be the same across all your

[danielk at prude ~]$ grep mythtv /etc/passwd
[danielk at prude ~]$ grep mythtv /etc/group

[danielk at cuy ~]$ grep mythtv /etc/passwd
[danielk at cuy ~]$ grep mythtv /etc/group

If they don't agree you can't authenticate. Also if you run the
backend as root you generally can't write to NFS shares because
most NFS implementations only give the root account guest access
if they give it any access at all.

You can edit the numbers in the passwd and group files on one
computer so they agree with the other one, but make sure you
chown mythtv:mythtv -R /directory/that/should/be/owned/by/mythtv
on all directories used by the mythtv account afterward, this
includes /home/mythtv and all your local recording directories
and any directories used by any plugin.

FYI In large unix installations there is usually an account
server such as yp, so this doesn't happen. But desktop Linux
distro's don't use such things by default.

-- Daniel

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