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.
>
> --
> Paul Heinlein <> heinlein@xxxxxxxxxx <> http://www.madboa.com/
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