Re: nfs mounting
"Andrew M.A. Cater" <amacater@galactic.demon.co.uk> writes:
> On Sun, Sep 21, 2014 at 02:48:59AM +0200, lee wrote:
>> Hi,
>>
>> any idea why an NFS volume is being unmounted when a VM runs out of
>> memory and kills some processes? These processes use files on the NFS
>> volume, but that's no reason to unmount it.
>>
>
> The OOM process killer is not necessarily aware: it will kill processes until memory usage
> works again - and going OOM is, itself, a sign that something is fairly drastically wrong.
The VM needs more memory which the server doesn't have. For now, I
assigned more swap space to the VM.
The process killed was seamonkey. Killing seamonkey frees at least 1GB.
> Suppose:
>
> There's heavy NFS usage and stuff is queueing to get on and off the mount / high disk I/O
NFS usage isn't heavy.
> and the kernel hits a stuck "something" - memory usage may spike and the OOM will eventually
> kill processes.
Even NFS processes, after freeing 1GB+ by killing seamonkey?
> If something is using the NFS and there are stale mounts, that prevents
> clean unmounting ... further problems.
There's only one mount, and it isn't stale.
> Under high I/O I've occasionally seen information
> messages where the kernel is backing off for 120s and the note that you can disable further
> displays of this message by cat'ing something into proc. [Hey, it's a Sunday morning and
> I can't remember everything :)
There wasn't much I/O going on. Seamonkey was actually idling while I
was doing something else that doesn't touch the VM seamonkey was running
in in any way.
> If a disk is being left unclean / marked as such, it won't be automatically mounted,
> of course. If there's a problem with a remote mount / dead file handles that will also
> clobber it.
The VM seamonkey was running in doesn't export anything via NFS. It
only mounts a volume exported by another VM. The export was fine or I
would have noticed on my desktop because it has the same volume mounted
the same way (/home) and would have frozen up.
>> Also annoying: The volume doesn't get mounted when booting despite it's
>> in /etc/fstab. I have to log in into the VM and mount it manually. The
>> entry in fstab is correct: I can just say 'mount /mountpoint' and it's
>> mounted. Is that some Debian-specific bug?
>>
>
> What's the entry? [Too many times, I've seen a typo or something anomalous only
> once I've called a colleague in to have a look :) ]
jupiter:/srv/data_home /home nfs defaults 0 0
--
Knowledge is volatile and fluid. Software is power.
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