Date: Sat, 26 Apr 2014 15:47:31 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: FreeBSD Filesystems <freebsd-fs@freebsd.org> Subject: RFC: using ceph as a backend for an NFSv4.1 pNFS server Message-ID: <507714298.1684844.1398541651089.JavaMail.root@uoguelph.ca>
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Hi,
The non-pNFS v4.1 server in the projects area is just about ready
for head, I think. However, without pNFS, NFSv4.1 isn't all that
interesting. The problem is that doing a pNFS server is a non-trivial
exercise. I am now somewhat familiar with pNFS (from doing the client
side), but have no expertise w.r.t. cluster file systems, etc.
For those not familiar with pNFS, the basic idea is that the NFSv4.1
server becomes a metadata server (MDS) and hands out what are called
layouts and devinfo, so that the client can access data server(s) (DS)
to read/write the file. There are RFCs that define both block/volume
(using iSCSI or similar) and object (using something called ODS2).
Although I suspect there are many ways to do a pNFS server, I think
that building it on top of a cluster file system may be the simplest.
So, this leads me to...
At a glance (just the web pages, I haven't looked at the source),
it appears that ceph might be useful as a backend to a pNFS server.
It has a POSIX interface (that could be used by the metadata server)
as well as both object (not ODS2 I suspect) and block interfaces.
The licensing appears to be LGPL, which isn't ideal, but I'd say
better than GPLv3 (which is what Glustre appears to be).
Does anyone have experience using ceph or some other cluster
file system such that you might have some idea w.r.t. its
usefulness for this?
Any other comments w.r.t. this would be appreciated, including
generic stuff like "we couldn't care less about pNFS" or technical
details/opinions.
Thanks in advance for any feedback, rick
ps: I'm no where near committing to do this at this point and
I do realize that even completing the ceph port to FreeBSD
might be beyond my limited resources.
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