[Gluster-devel] Multiple NFS Servers (Gluster NFS in 3.x, unfsd, knfsd, etc.)

[Shehjar Tikoo]

Gordan Bobic wrote:
> Martin Fick wrote:
>> --- On Wed, 1/6/10, Gordan Bobic <gordan at bobich.net> wrote:
>>
>>>> With native NFS there'll be no need to first mount a
>>> glusterFS
>>>> FUSE based volume and then export it as NFS. The way
>>> it has been developed is that
>>>> any glusterfs volume in the volfile can be exported
>>> using NFS by adding
>>>> an NFS volume over it in the volfile. This is
>>> something that will become
>>>> clearer from the sample vol files when 3.0.1 comes
>>> out.
>>>
>>> It may be worth checking the performance of that solution
>>> vs the performance of the standalone unfsd unbound to
>>> portmap/mountd over mounted glfs volumes, as I discovered
>>> today that the performance feels very similar to native
>>> knfsd and server-side AFR, but without the fuse.ko
>>> complications of the former and the buggyness of the latter
>>> (e.g. see bug 186: 
>>> http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=186
>>> - that bug has been driving me nuts since before 2.0.0 was
>>> released)
>>>
>>> I'd hate to see this be another wasted effort like booster
>>> when there is a solution that already works.
>>

booster was not a wasted effort at all. It has received less
attention over the last month or so because of the NFS xlator
taking all my time, but before that it provided us and those
who tested it for production systems, a short-term solution
that performed better than unfsd-over-FUSE. I verified that there
were clear performance benefits of using unfsd-booster.

>> I don't think it would be wasted if it includes NLM since unfsd does 
>> not do locking!
> 
It does not do decent security either. One of our goals is to
implement kerberos5 based authentication. We also want
to support NFS over RDMA and NFSACLs. For extending to these,
unfsd code is highly limiting.

> Arguably it just replicated the functionality of server side volume 
> assembly and exporting just the assembled volume.

Replication of existing functionality is not such a bad
thing when you consider the extended functionality and performance
goals we are aiming for with native NFS. We figured the benefits were
worth the cost.

> Whether the end client 
> connects via nfs or glfs is largely immaterial for the sake of 
> installing an additional package on the client. The bug mentioned above 

No, it is not immaterial. The overhead of installing additional
packages is a real concern in some of the deployments we're
aiming for.

It is not immaterial wrt how clients connect either. NFS is a
well understood protocol. It gives us all the advantages of
supporting a standardized protocol.

> that shows up under that scenario, however, is probably a far more 
> critical issue than what the client connection protocol is. I've said 
> this before - stability should come before features, especially when 
> features are replicating what can already be achieved with only 
> superficial differences.
> 

To rephrase what I said earlier, between unfsd-based approaches
and native NFS, the difference will be far more than
superficial.

Thanks
-Shehjar

> Gordan
> 
> 
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