[mythtv-users] Shared filesystem that looks different to different machines

Raymond Wagner raymond at wagnerrp.com
Wed Jun 4 23:21:14 UTC 2014


On 6/4/2014 1:40 PM, Joseph Fry wrote:
>
>             I don't believe that NFS would have any issue with nesting a
>             mount inside another mount like this, after all the OS just
>             treats it as another filesystem and every linux system I
>             have ever seen does this (/dev, /proc, etc).
>
>
>         NFS can have issues if you mount one NFS volume within another
>         NFS volume.  If access to the lower volume is ever anything but
>         100% stable, and the mount point for the upper volume is lost,
>         bad things happen.  It's the same reason why you never use an
>         NFS share for swap space.
>
>
>     Mounting one NFS filesystem on another NFS filesystem has been
>     commonly used from the beginning of NFS: diskless systems did this
>     all the time.
>
>
> I could see problems like Raymond describes if it were two different NFS
> servers and you were nesting... but on the same server, I'd imagine that
> if one went, the other would as well anyway.

I've had issues even when using only one NFS server. The mountpoint 
basically becomes a black hole. Any process that tries to touch that 
branch of the filesystem is irrecoverably blocked (SIGKILL can't even 
touch them), and the system can only be fixed by a reboot.


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