Gordan Bobic wrote:
Shehjar Tikoo wrote:
Gordan Bobic wrote:
Martin Fick wrote:
--- On Wed, 1/6/10, Gordan Bobic <gor...@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.
A solution so short term that I missed it entirely while still fighting
stability issues...
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.
So why exactly use NFS instead of GlusterFS with server-side brick
assembly? What is the advantage? I cannot see one either in terms of
performance or functionality. This is what I would be using if I could
get that setup to work without bugginess (e.g. bug 186) and crashing
(see other emails on this thread, will try to re-create and provide
backtraces).
If using GlusterFS fits your setup, you should continue to,
but there are cases where users are not *willing* to or *can* not use
GlusterFS. See later for why.
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.
What are the performance and functionality benefits over using GlusterFS
protocol as I described above (e.g. in my case server-side AFR, with
just the AFR-ed volume exported to the client)?
Thats not the relevant question here, IMO. Most people who will use
NFS rather than GlusterFS would be those who either do not have a
choice in the matter or do not want the overhead of choosing.
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.
I thought you were talking about bolting kerberos authentication onto it
and running it over RDMA. That doesn't sound very standard.
But it is standardy. Both, kerberos based authentication and NFS over
RDMA.
I'm not criticizing the idea per se, I'm just trying to figure out why
it is actually useful, and I've not been able to work that out yet from
what has been said.
The answer to that lies in another question, "why would anyone use
a standardized NFS over GlusterFS?"
Here are three points from pnfs.com on why:
1. Ensures Interoperability among vendor solutions
2. Allows Choice of best-of-breed products
3. Eliminates Risks of deploying proprietary technology
I'll add a fourth one:
Familiarity of the protocol, is very important, especially
in the storage world, where conservatism is preferred over
fancy technology. NFS has been tried and tested over 2 decades.
HTH
-Shehjar
Gordan
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