Re: Use of automounter for permanent mounts?



On Mon, 4 Jun 2007 23:27:29 +0100, Tim Bradshaw <tfb@xxxxxxxx> wrote:

On 2007-06-04 21:50:13 +0100, Michael Vilain <vilain@xxxxxxxxxxx> said:

How were the NFS volumes mounted in vfstab
(hard or soft mounts)?

Never use soft mounts unless all your applications *intimately*
understand NFS. It's possible such applications exist.

Thanks to both of you for the advice.

The NFS volumes are currently hard-mounted in vfstab and I realise
that automounted directories will hang in the same way as hard-mounted
directories. That isn't too much of a problem in this application,
where it's hanging caused by the disappearance of
infrequently-accessed volumes that's causing the concern.

However it probably won't achieve what you (or the customer hopes for)
- things tend to get mounted and stay mounted with most patterns of
use. Most of the benefit of the automounter is central administration
in my experience.

The perceived advantage of the automounter is that not all of the
remote volumes are needed all of the time (some are accessed
infrequently), so automounting would keep them available but it
wouldn't cause any side-effects if they disappear during a period when
they aren't being accessed. So it's perhaps reasonable to use the
automounter for these but the only benefit of using it with permanent
mounts seems to be the central administration.

Is there any way to make the files local to the web server?

Not really. There's 2 TB of data and it's distributed among several
NAS devices and other Solaris machines, some of it off-site.

I think it's pretty reliable now (it used to be crap a long time ago).

That's reassuring, thanks.

One last point: is there any performance impact when using the
automounter *once the volumes are mounted*? I can understand how
there's likely to be a small delay on the first access, while the
automounter arranges for the volume to be mounted, but I'm unsure
about what happens afterwards. Is performance the same as for a
hard-mounted volume or is there an overhead with every access to
/net/host/whatever going through the automounter?

Mike.

.



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