From: "J. Bruce Fields" <bfields@fieldses.org>
To: Chuck Lever <chuck.lever@oracle.com>
Cc: Jeff Layton <jlayton@redhat.com>, linux-nfs@vger.kernel.org
Subject: Re: [PATCH v4 0/6] nfsd: overhaul the client name tracking code
Date: Wed, 25 Jan 2012 15:53:40 -0500 [thread overview]
Message-ID: <20120125205340.GA21335@fieldses.org> (raw)
In-Reply-To: <7D6EA28C-26F1-46A3-B1C5-6BC6F6AE713D@oracle.com>
On Wed, Jan 25, 2012 at 03:29:34PM -0500, Chuck Lever wrote:
>
> On Jan 25, 2012, at 1:55 PM, J. Bruce Fields wrote:
>
> > On Wed, Jan 25, 2012 at 12:41:27PM -0500, Chuck Lever wrote:
> >> If SETCLIENTID returns a unique clientid4 that a client hasn't seen from other servers, the client knows that's a unique server instance which must be recovered separately after a reboot.
> >
> > Hm, but does it have to do the recovery with that server?
>
> If a client has a lease and open state on that server, it should do recovery if the server reboots.
Yes, but does it have to do it against *that* server, or could it
recover against another?
Again, as long as failover is allowed, I think the latter is too.
> > And if so, then how does that fit with failover?
>
> We were supposed to discuss that with Bill and Piyush. Maybe we can bring it up again at Connectathon. But my assumption is that fail over is supposed to look like a server reboot.
That's what I assume too: but that means, if I'm a client, and I fail
over from server A to server B, and server B gives me a STALE error: I
don't know if that's just because I failed over, or if in fact A and/or
B did just reboot.
And from the point of view of the servers: they don't know if the state
I'm trying to reclaim is state I previously held from server A, or if
it's some other state that I previously held on server C (but then lost,
unbeknownst to me, due to a network partition that lost my RENEWs to C).
So I guess the servers would be stuck trying to track all that state
across reboots?
> The question is what clients does the server allow to recover, and which does it force to start fresh? Shouldn't it be enough for a server to remember nfs_client_id4 strings?
>
> > I mean, suppose the whole cluster is rebooted. From the client's point
> > of view, its server becomes unresponsive. So it should probably start
> > pinging the replicas to see if another one's up. The first server it
> > gets a response from won't necessarily be the one it was using before.
> > What happens next?
>
> Again, it depends on whether your clustering implementation shares state among all servers in the cluster.
Assume for now it doesn't.
--b.
next prev parent reply other threads:[~2012-01-25 20:53 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-23 20:01 [PATCH v4 0/6] nfsd: overhaul the client name tracking code Jeff Layton
2012-01-23 20:01 ` [PATCH v4 1/6] nfsd: add nfsd4_client_tracking_ops struct and a way to set it Jeff Layton
2012-01-23 20:01 ` [PATCH v4 2/6] sunrpc: create nfsd dir in rpc_pipefs Jeff Layton
2012-01-23 20:01 ` [PATCH v4 3/6] nfsd: convert nfs4_client->cl_cb_flags to a generic flags field Jeff Layton
2012-01-23 20:01 ` [PATCH v4 4/6] nfsd: add a header describing upcall to nfsdcld Jeff Layton
2012-01-23 20:01 ` [PATCH v4 5/6] nfsd: add the infrastructure to handle the cld upcall Jeff Layton
2012-01-23 20:01 ` [PATCH v4 6/6] nfsd: get boot generation number from upcall instead of boot_time Jeff Layton
2012-01-24 23:08 ` [PATCH v4 0/6] nfsd: overhaul the client name tracking code J. Bruce Fields
2012-01-24 23:11 ` J. Bruce Fields
2012-01-25 11:41 ` Jeff Layton
2012-01-25 13:11 ` J. Bruce Fields
2012-01-25 13:38 ` Jeff Layton
2012-01-25 16:47 ` Chuck Lever
2012-01-25 17:14 ` J. Bruce Fields
2012-01-25 17:41 ` Chuck Lever
2012-01-25 18:55 ` J. Bruce Fields
2012-01-25 20:23 ` Jeff Layton
2012-01-25 21:25 ` J. Bruce Fields
2012-01-25 21:29 ` Chuck Lever
2012-01-25 21:54 ` J. Bruce Fields
2012-01-25 21:55 ` Chuck Lever
2012-01-25 22:11 ` J. Bruce Fields
2012-01-27 15:43 ` Jeff Layton
2012-01-25 20:29 ` Chuck Lever
2012-01-25 20:53 ` J. Bruce Fields [this message]
2012-01-25 21:08 ` Chuck Lever
2012-01-25 19:08 ` Jeff Layton
2012-01-24 23:10 ` J. Bruce Fields
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