On Wed, Jul 27, 2016 at 11:40:38PM +0100, Sean Brisbane wrote:
> There is a slight performance related reason for exporting disk partitions
> individually, the performance boost is server-side as Paul says. The
> advantage is that the no_subtree_check can be used without any additional
> security risk.
>
> It is probably the case that the /export/base/a is a partition, is exported
> with no_subtree_check, and therefore there is a small performance boost.
>
> Preventing server side mount point traversal can also form part of a
> security mechanism if servers have different security options for different
> mount points, but in this case mounting server:/export/base wouldn't give
> you the same client view of the filesystem tree as mounting each
> individually if it worked at all.
>
> Cheers,
> Sean
>
> On 27 July 2016 at 23:21, Paul Heinlein <heinlein@xxxxxxxxxx> wrote:
>
> > On Wed, 27 Jul 2016, Frank Thommen wrote:
> >
> > Hello,
> >>
> >> does it in any respect (throughput/performance, cpu load, I/O load,
> >> resilience, ...) matter, if one mounts subdirectories of an NFS (v3) export
> >> into separate directories or if one just mounts the parent directory?
> >>
> >> I.e. like this:
> >>
> >> server: /export/base/a -> /mnt/a
> >> server: /export/base/b -> /mnt/b
> >> server: /export/base/c -> /mnt/c
> >> server: /export/base/d -> /mnt/d
> >> server: /export/base/e -> /mnt/e
> >>
> >> or simply like this:
> >>
> >> server:/export/base -> /mnt
> >>
> >
> > Performance wise, any bottleneck will almost certainly be tied to the
> > disks on the back end, not the nfs process itself.
> >
> > There are a couple good reasons for splitting up the mounts:
> >
> > 1. They can have different export restrictions (e.g., for different
> > client hosts, ro vs. rw permissions, user squashing).
> >
> > 2. /base/[a-e] live on different RAID arrays and might benefit from
> > different management cycles; that'd also be a case where multiple
> > exports might be a good idea. That said, I've never managed an
> > exported filesystem consisting of different arrays; we've always
> > exported at the RAID level or below.
Exporting them individually also prevents the remote system from
accessing /mnt/[!abcde] that you did not intend to make available.
Jon
--
Jon H. LaBadie jon@xxxxxxxxxx
11226 South Shore Rd. (703) 787-0688 (H)
Reston, VA 20190 (703) 935-6720 (C)
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