On Fri, 2011-11-11 at 10:31 +0000, Andrew Cooper wrote: > On 10/11/11 20:43, Trond Myklebust wrote: > > On Thu, 2011-11-10 at 15:52 +0000, Andrew Cooper wrote: > >> On 10/11/11 15:29, Chuck Lever wrote: > >>> On Nov 10, 2011, at 6:15 AM, Andrew Cooper wrote: > >>> > >>>> On 09/11/11 22:36, Chuck Lever wrote: > >>>>> On Nov 9, 2011, at 1:38 PM, Andrew Cooper wrote: > >> Sorry. I am not sure I was clear. An EIO does not present itself with > >> a hard mount, but a TCP FIN is still injected into the stream by the > >> client, causing 15 seconds of deadlock, eventually fixed by sending a > >> RST and restarting with a new TCP stream. At this point, softmounts > >> throw an EIO while hardmounts restart and continue successfully. > >> > >> My problem is not the EIO on softmount or lack of EIO for hardmout, but > >> the fact that the client sees fit to try and close the TCP stream while > >> an apparently otherwise healthy NFS session is ongoing. > > The client will attempt to close the TCP connection on any RPC level > > error. That can happen, e.g., if the server sends a faulty RPC/TCP > > record fragment header or some other garbage data. > > > > I'm assuming that you've checked that the TCP parameters are set to sane > > values for a 10GigE connection (i.e. tcp_timestamps is on) so that there > > is no corruption happening at that level? > > > > Cheers > > Trond > > I have a TCPdump/wireshark analysis of the entire packet stream (4GiB). > I cant see any RPC level errors (rpc.replystat != 0 yields no matches). > What specifically would I be looking for? Wireshark seems not to have > any problem decoding any of the RPC packets, so I hope that indicates no > RPC level corruption. > > There is one case where the server sends a double write reply for the > same write, with different length fields. However, this is a good 20 > seconds before the FIN is sent, so I was hoping that it was unrelated. > Might it not be? Can you send us just that portion of the trace so that we can have a look? > As for TCP timestamps; I have a Timestamp option in each TCP packet. > Nothing appears corrupted. What would I be looking for with corrupted > timestamps? I just meant that you should check that you've enabled tcp window scaling and timestamps in order to avoid problems with wrapped sequence numbers (See http://tools.ietf.org/html/rfc1323 for details). On Linux this means that you need to check sysctl net.ipv4.tcp_timestamps and sysctl net.ipv4.tcp_window_scaling They should both be set to the value '1'. Cheers Trond -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@xxxxxxxxxx www.netapp.com -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
