[Linux-cluster] Cluster NFS causes kernel bug

[Ward, Timothy - SSD]

On Tue, 23 Oct 2007, Gordon wrote:

>> NFS 1.0.9-16 (BAD)
>> 
>> So I am avoiding Fedora and GFS2 until you've had more time to "bake"
it.
>> 
>> I am reading up on Wendy Chang's NFS linux-cluster postings to
>> understand why NFS fail over is not consistent.
> 
> What do you mean by "consistent"?
> 
>> - Has anyone successfully setup a failover NFS cluster?
> 
> You'll have to reveal more about your setup. Are you using a floating
IP and HA to fail over the NFS service, with GNDB for the mirrored block
device? A > SAN with a shared GFS file system with multiple nodes
exporting the NFS file system? Or something entirely different? 
> 
>> - Does nfsv4 work better?  It appears by default fedora6 uses nfsv3
(tcp) client and
>>   is flaky.
> 
> NFS over TCP has always been flaky, and from what I've seen NFSv4 is
not really any better. I'm still using NFSv3 over UDP for everything, as
it seems > > most reliable. 
> 
> Gordan

Gordon,

More detail:
- SAN FibreChannel array connected to a SAN switch with 2 of the 3 nodes
connected to it as well
- GFS1 fs mounted on the 2 nodes (So both SMB and NFS can access the
same files)
- A floating IP for the NFS service.  The failover domain only allows it
to go to one of the 2 SAN connected nodes
- A Samba service setup on the 2nd node but able to fail to the first
- NFS running on both nodes at all times, but only being cluster served
via the floating IP by one node

1) By "not consistent" I mean that when I failover from 1 node to
another node the NFS service fails just fine.  Its the client connection
that is painful.  Sometimes the client (FC6 in this case, building a
CentOS 5 as we speak) reconnects to the server "immediately", sometimes
within minutes, or an hour or never.

2) Thanks for the report on NFSv3/UDP.  From my reading that sounded
like something to avoid, but maybe I need to try it anyway.  How
reliable has it been?  Do the clients reconnect most times?

Thanks for the reply :)
Tim
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