[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [Linux-cluster] slow NFS performance on GFS2

OK, I don't know much about increasing NFS performance, but I do have
some things for you to consider that may actually help anyway:

In general we (the cluster support group at RedHat) have started
recommending that you just not even use GFS or GFS2 for use as an
exported FS from a cluster.  The reason being that if you follow
all the rules, these filesystems don't usually buy you anything.
While a GFS or GFS2 filesystem is exported, you shouldn't have any
other type of access to it, and then only from one node at a time.
We recommend that you don't even mount on more than one node at
a time.  You certainly should not NFS export it from more than one
node at a time.  You should not even export it as both NFS and CIFS
at the same time from the same node.  If memory serves correctly,
you shouldn't even use the FS for, say, a database on the same node
as the one you're exporting it from (I may be remembering that last
bit wrong, if it's important I can check, but I don't think it's
important to this discussion).

The point here is that because you can't use it from more than one
node at a time when you are exporting it, there's just no point in
using GFS or GFS2 at all.  This is not a high performance filesystem.
It was never intended to be.  It's primary advantage is that it can
be used on multiple nodes in a cluster at the same time.  If your
application (exporting it) takes that advantage away, you've lost
the main (possibly only) advantage in using it.

Steve Whitehouse actually touched on this when he asked if you had
it set up active/passive, but I didn't see where you answered that
question (I may have missed it, though).

Now, if you still want to use GFS2, there are some things that I can
help you with from the GFS side that can speed it up considerably
(depending on the kind of access going on with it), which may actually
turn out to be the cause of the problem that you're experiencing
(interaction between NFS and GFS2), but I would first recommend that
you use a different filesystem all together if your only purpose for
it is NFS exporting.

I'm sorry I don't have much advice to give for the NFS specific
stuff, though.


On Tue, Sep 24, 2013 at 02:08:01PM +0200, Olivier Desport wrote:
> Le 24/09/2013 14:03, Raymond Burkholder a e'crit :
>         One possibility is to try changing rsize and wsize at the client end. Is
>         the 10G network used for NFS the same network as the one used for the
>         iSCSI?
>         I've tried several values of rsize and wsize and it doesn't
>         change anything.  iSCSI and NFS are not on the same VLAN. I'm
>         testing with servers which are on the same chassis (NFS/GFS
>         servers are on blades and client is a KVM guest with virtio
>         network card). iSCSI and NFS use separates network in the
>         chassis but each blade has to share iSCSI (50% to 100%
>         of 10 Gbits/s) and LAN (50% to 100%).
>         iperf between server and client : 3.4 Gbits/s (435 Mbytes/s).
>     You could also try using Jumbo Frames on the network.
> I've tried but the NFS speed is the same.
> -- 
> Linux-cluster mailing list
> Linux-cluster redhat com
> https://www.redhat.com/mailman/listinfo/linux-cluster

[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]