Re: NFS stops responding

[Jason Holmes <jholmes@psu.edu>]

Here's a 'sysrq-T' listing for a few hung processes.  Unfortunately, 
this was on a 2.4.21-20.ELsmp RedHat kernel and not a vanilla kernel 
(I'll send one of those along as soon as I can get one):

xauth         D 00000100e2d30370  1312  9600   9599 
(NOTLB)

Call Trace: [<ffffffff80120d8a>]{io_schedule+42} 
[<ffffffff801420ed>]{___wait_on_page+285}
        [<ffffffff8014316a>]{do_generic_file_read+1258} 
[<ffffffff80143770>]{file_read_actor+0}
        [<ffffffff801438c5>]{generic_file_new_read+165} 
[<ffffffffa02ec3a9>]{:nfs:nfs_file_read+217}
        [<ffffffff8015dfd2>]{sys_read+178} 
[<ffffffff80110177>]{system_call+119}

bash          D 00000100e2bef130   824  9614      1          9666  9583 
(NOTLB)

Call Trace: [<ffffffff80120d8a>]{io_schedule+42} 
[<ffffffff801420ed>]{___wait_on_page+285}
        [<ffffffff8014316a>]{do_generic_file_read+1258} 
[<ffffffff80143770>]{file_read_actor+0}
        [<ffffffff801438c5>]{generic_file_new_read+165} 
[<ffffffffa02ec3a9>]{:nfs:nfs_file_read+217}
        [<ffffffff8015dfd2>]{sys_read+178} 
[<ffffffff80110177>]{system_call+119}

bash          D 00000100db051e28     0  9666      1          9718  9614 
(NOTLB)

Call Trace: [<ffffffff80120d8a>]{io_schedule+42} 
[<ffffffff80142466>]{__lock_page+294}
        [<ffffffff801430ca>]{do_generic_file_read+1098} 
[<ffffffff80143770>]{file_read_actor+0}
        [<ffffffff801438c5>]{generic_file_new_read+165} 
[<ffffffffa02ec3a9>]{:nfs:nfs_file_read+217}
        [<ffffffff8015dfd2>]{sys_read+178} 
[<ffffffff80110177>]{system_call+119}

Thanks,

--
Jason Holmes

Jason Holmes wrote:
> I have had similar problems with NFS recently and have yet to figure out 
> a pattern.  They started around the 2.4.27 time frame, but that could 
> just be coincidental.  I have 8 NFS servers and several hundred clients. 
>  Every few days, one of the clients will start hanging connections to 
> one of its mounts (all of the processes access that mount go into D 
> state and never return - the machine has to be forcefully rebooted to 
> get rid of them).  While one of the client machines are hanging on a 
> mount, the other client machines are fine.  Access to the other mounts 
> are fine on the hanging machine.  The server is fine when this happens 
> and I see no odd messages in the logs.
> 
> The servers were originally running RedHat Enterprise 3 kernels - I have 
> also tried 2.6.8.1 and have had the same problem.  Clients have been 
> 2.4.27, 2.6.8.1, and the latest RedHat kernels.  The network is a simple 
> private one and there is no packet loss.  I've tried both UDP and TCP v3 
> hard mounts.  Exports are synchronous.
> 
> I'm currently hoping that one of my machines with sysrq enabled will 
> hang to see if I can possibly get some information out of that that will 
> shed some light on the situation.  I'd be happy to entertain any other 
> debugging suggestions on this.  Unfortunately, I haven't been able to 
> figure out how to force the problem to happen, so I'm at the mercy of 
> waiting for it to just pop up.
> 
> Thanks,
> 
> -- 
> Jason Holmes
> 
> Douglas Furlong wrote:
> 
>> Good morning all.
>>
>> Considering the exceedingly fast and speedy response I got yesterday
>> with regards to my problem accessing edirectory.co.uk I thought I would
>> try my luck with an NFS problem.
>>
>> All our unix systems at work have their home directory mounted via NFS
>> to allow hot seating (not that they ever use it!).
>>
>> I have just recently upgraded to Fedora Core 2, running the most recent
>> kernel.
>>
>> All the workstations are running Fedora Core 2, with the second from
>> last kernel (due to CIFS/SMB problems in the latest one).
>>
>> Unfortunately there are two users who's connection to the NFS server is
>> dropped and does not seem to want to reconnect. To date I have.
>>
>> 1) Replaced both of their PC's
>> 2) Replaced switch
>> 3) will replace network cables tomorrow
>> 4) I have tried numerous version of the kernel including the testing
>> kernel from rawhide.
>> 5) Tried variations in the timeo=x value to see if that will help.
>>
>> These lockups vary in time between 30 minutes and 5 hours. Network
>> connections are not affected by this lock up, I am able to ssh on to the
>> box (that's how I collected the tcpdump data).
>>
>> I also have two windows PC's on this switch and things appear to be
>> fine.
>>
>> I have 7 or 8 other systems running linux on the network and NFS
>> communication is not affected.
>>
>> I have increased the number of servers on the NFS server from 8 to 16. I
>> did this by editing /etc/init.d/nfs (don't think this is of any help).
>>
>> I took some tcpdump info on both the client and the server to try and
>> see if I can work out what is going on. Initially it is not providing me
>> with much information (but loads of data).
>>
>> I have attached two files, one from the client and one from the server.
>> Main reason for attaching them is due to length of data. I had wanted to
>> attach them as plain text to simplify access, but at 100k it's a bit too
>> large.
>> I didn't want to cut them down too much just in case I removed some
>> pertinent information :(
> 
> 
> 
> 
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