mount -u -o rw / not working on NFS?

James Harrison jamesh at
Mon Nov 19 10:01:13 PST 2007

On Mon, 2007-11-19 at 18:33 +0100, Laszlo Nagy wrote:
>   Hi All,
> I have a system where a diskless FreeBSD 6.3 i386 machine boots with pxeboot from a FreeBSD 6.3 amd64 machine. I have lines in /etc/fstab for the diskless machine like:
> # Device        MountPoint      FsType  Options Dump    Pass
> /usr    nfs     rw      0       0
>  /root   nfs     rw      0       0
> The machine boots from network nicely, then I can login as root and invoke these commands:
> mount -u -o rw /
> mount -u -o rw /usr
> mount -u -o rw /root
> There is no error message on the console, nor in the system log. However, this happens afterwards:
> diskless101#mkdir /aaa
> mkdir aaa: Read-only file system
> Question: if the remount did not succeed, why didn't it throw an error? If succeeded, why can't I write on the filesystem?
> Thanks,
>    Laszlo

The answer to the second portion is that you're mounted as a read only
file system, so there's no write access.

There's an nfs permissions file you may need to edit, /etc/exports/,
which controls whether NFS shares the file system as read only, read
write, whether root can have root on the file system etc.


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