NFS and Kernel 2.6.27*

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NFS and Kernel 2.6.27*

Postby Arthur_Dent » Mon Dec 15, 2008 11:44 am

Hello all,

I have 2 machines which I call my "server" and my "client" (they're not really full-blown client/server configuration, but the "server" in on 24/7 and does mail processing, web hosting and stuff).

Both machines are fully updated Fedora 9 boxes. Sometime back around Fedora Core 2 or 3 I set up NFS so that I could easily access files on the server from the client machine. This has worked faultlessly ever since (and I forget how I did it).

Following a recent update from kernel 2.6.26* to 2.6.27* it stopped working. There are no reported errors and NFSd is up and running on both machines. Opening Nautilus on the client machine however will cause it to hang.
Accessing one of the exported directories via a terminal will occasionally work, but will more often freeze too.
The only other indication of a problem is this in /var/log/messages:
Dec 15 11:18:17 localhost kernel: nfs: server 192.168.123.101 not responding, still trying

The client IP is correctly listed in /etc/exports on the server.

Reverting to the 2.6.26* kernel on the server solves the problem.

What might be causing this?

Thanks in advance for any help or suggestions...

Mark
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RE: NFS and Kernel 2.6.27*

Postby i.couchman » Mon Dec 15, 2008 1:12 pm

Mark,
I had a similar problem with debian etch. It turned out to be a firewall problem due to lockd & mountd (if I remember rightly) using random ports. This is what I do now, which works for me :)

Add RPCMOUNTDOPTS=-p815 to /etc/defaults/nfs-kernel-server

Allow ports 815&816 in firewall

for each client:
add
options lockd nlm_udpport=2050 nlm_tcpport=2050
to /etc/modprobe.d/options.local
Allow port 2050 in firewall

then restart everything. Fedora may use different files (I haven't used redhat-based systems for many years) Try disabling the firewall before you try this. If nfs works, that's your problem!
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Postby Arthur_Dent » Mon Dec 15, 2008 2:39 pm

Hi Ian,

Thanks for the suggestion. Unfortunately turning off the firewall made no difference. (Also I do not have a /etc/defaults/* directory, nor a /etc/modprobe.d/options.local file - so I guess Debian and Fedora are only distant cousins...)

I have reverted to the 2.6.26* kernel on the server and everything works as expected (without changing any configuration settings). What can have changed between 2.6.26 and 2.6.27 to cause this problem?

Is it only me?

Any other ideas for things to try?...

Thanks again

Mark
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Postby i.couchman » Mon Dec 15, 2008 2:45 pm

sorry, Mark. I don't know enough about redhat-based systems. :(
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Postby jolharg » Mon Dec 15, 2008 3:06 pm

Maybe the packagers accidentally left out a vital kernel piece in 2.6.27? You could always try building from source ;)
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Postby Arthur_Dent » Mon Dec 15, 2008 3:13 pm

Well actually this is the 3rd 2.6.27 kernel release so far on F9 (I keep hoping that each next release will fix the problem) but so far no luck.
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Postby Ram » Mon Dec 15, 2008 4:17 pm

As it changed over to using the newer version of NFS, version 4 I think.

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Postby Arthur_Dent » Mon Dec 15, 2008 4:37 pm

Yes, I think you might be right. Does NFS4 require any different configuration?
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Postby Ram » Mon Dec 15, 2008 11:19 pm

now sure, looking at YaST on my openSUSE11 box NFSv4 is enable and here a line from the /etc/export file that I share out the home folder directories to my Ubuntu boxes.

/srv/home/ * (fsid=0,rw,root_squahed,sync,no_subtree_check)

There are a few commands you could try to see what's what on your system, like seeing if the export point is visible etc. I see if I can dig them out for you.

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Postby Arthur_Dent » Tue Dec 16, 2008 11:36 am

Ram wrote:There are a few commands you could try to see what's what on your system, like seeing if the export point is visible etc. I see if I can dig them out for you.


Thanks Ram, that would be very helpful...

Thank you.


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Postby Ram » Tue Dec 16, 2008 10:54 pm

On the NFS server run rpcinfo -e this lists ports used and for what version of NFS, man rpcinfo for more info

Code: Select all
user@server:~$ rpcinfo -p
   program vers proto   port
    100000    2   tcp    111  portmapper
    100000    2   udp    111  portmapper
    100024    1   udp  42189  status
    100024    1   tcp  39297  status
    100003    2   udp   2049  nfs
    100003    3   udp   2049  nfs
    100003    4   udp   2049  nfs
    100021    1   udp  51833  nlockmgr
    100021    3   udp  51833  nlockmgr
    100021    4   udp  51833  nlockmgr
    100003    2   tcp   2049  nfs
    100003    3   tcp   2049  nfs
    100003    4   tcp   2049  nfs
    100021    1   tcp  47182  nlockmgr
    100021    3   tcp  47182  nlockmgr
    100021    4   tcp  47182  nlockmgr
    100005    1   udp  44951  mountd
    100005    1   tcp  46326  mountd
    100005    2   udp  44951  mountd
    100005    2   tcp  46326  mountd
    100005    3   udp  44951  mountd
    100005    3   tcp  46326  mountd


On the client use showmount -e nfs server hostname or IP this should list what exports can be seen, again use man page for more info.

Code: Select all
user@client:~$ showmount -e server name
Export list for server name:
/srv/home                          *
/media/backups                     *



If you don't see anything try turning of your firewall and recheck.

As a side note: Depending on where you have mounted the share, it can also dictate whether you can see an icon for it or not. In Ubuntu shares mounted in /mnt are not visible whereas if mounted in /media they are.

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Postby Arthur_Dent » Wed Dec 17, 2008 10:20 am

OK - I'm a blithering wreck now...

I've tried everything I can think of.

Firstly, with thanks to Ram, here's the output of the rpcinfo checks:

With server booted in kernel 2.6.26
Code: Select all
[root@mydomain ~]# uname -a
Linux mydomain.com 2.6.26.6-79.fc9.i686 #1 SMP Fri Oct 17 14:52:14 EDT 2008 i686 i686 i386 GNU/Linux
[root@mydomain ~]# rpcinfo -p
   program vers proto   port  service
    100000    4   tcp    111  portmapper
    100000    3   tcp    111  portmapper
    100000    2   tcp    111  portmapper
    100000    4   udp    111  portmapper
    100000    3   udp    111  portmapper
    100000    2   udp    111  portmapper
    100024    1   udp  48963  status
    100024    1   tcp  59068  status
    100011    1   udp    875  rquotad
    100011    2   udp    875  rquotad
    100011    1   tcp    875  rquotad
    100011    2   tcp    875  rquotad
    100003    2   udp   2049  nfs
    100003    3   udp   2049  nfs
    100003    4   udp   2049  nfs
    100021    1   udp  44745  nlockmgr
    100021    3   udp  44745  nlockmgr
    100021    4   udp  44745  nlockmgr
    100003    2   tcp   2049  nfs
    100003    3   tcp   2049  nfs
    100003    4   tcp   2049  nfs
    100021    1   tcp  33601  nlockmgr
    100021    3   tcp  33601  nlockmgr
    100021    4   tcp  33601  nlockmgr
    100005    1   udp  52329  mountd
    100005    1   tcp  53731  mountd
    100005    2   udp  52329  mountd
    100005    2   tcp  53731  mountd
    100005    3   udp  52329  mountd
    100005    3   tcp  53731  mountd
[root@mydomain ~]# showmount -e
Export list for mydomain.com:
/home/mark     192.168.123.100
/mnt/datastore 192.168.123.100
/mnt/tempstore 192.168.123.100
[root@mydomain ~]#
and on the client side:
Code: Select all
[root@localhost ~]# showmount -e 192.168.123.101
Export list for 192.168.123.101:
/home/mark     192.168.123.100
/mnt/datastore 192.168.123.100
/mnt/tempstore 192.168.123.100
[root@localhost ~]#
Next with server booted in kernel 2.6.27
Code: Select all
[root@mydomain ~]# uname -a
Linux mydomain.com 2.6.27.7-53.fc9.i686 #1 SMP Thu Nov 27 02:29:03 EST 2008 i686 i686 i386 GNU/Linux
[root@mydomain ~]# rpcinfo -p
   program vers proto   port  service
    100000    4   tcp    111  portmapper
    100000    3   tcp    111  portmapper
    100000    2   tcp    111  portmapper
    100000    4   udp    111  portmapper
    100000    3   udp    111  portmapper
    100000    2   udp    111  portmapper
    100024    1   udp  51236  status
    100024    1   tcp  53405  status
    100011    1   udp    875  rquotad
    100011    2   udp    875  rquotad
    100011    1   tcp    875  rquotad
    100011    2   tcp    875  rquotad
    100003    2   udp   2049  nfs
    100003    3   udp   2049  nfs
    100003    4   udp   2049  nfs
    100021    1   udp  56698  nlockmgr
    100021    3   udp  56698  nlockmgr
    100021    4   udp  56698  nlockmgr
    100003    2   tcp   2049  nfs
    100003    3   tcp   2049  nfs
    100003    4   tcp   2049  nfs
    100021    1   tcp  37562  nlockmgr
    100021    3   tcp  37562  nlockmgr
    100021    4   tcp  37562  nlockmgr
    100005    1   udp  56364  mountd
    100005    1   tcp  57202  mountd
    100005    2   udp  56364  mountd
    100005    2   tcp  57202  mountd
    100005    3   udp  56364  mountd
    100005    3   tcp  57202  mountd
[root@mydomain ~]# showmount -e
Export list for mydomain.com:
/home/mark     192.168.123.100
/mnt/datastore 192.168.123.100
/mnt/tempstore 192.168.123.100
[root@mydomain ~]#
and on the client side:
Code: Select all
[root@localhost ~]# showmount -e 192.168.123.101
Export list for 192.168.123.101:
/home/mark     192.168.123.100
/mnt/datastore 192.168.123.100
/mnt/tempstore 192.168.123.100
[root@localhost ~]#
So actually, everything (to me at least) seems to be pretty much the same whether running 2.6.26 or 2.6.27.

However, it's still the case that when the server is in 2.6.27 those exported directories are not accessible. I am beginning to think that actually the problem lies not with NFS itself, but with something restricting NFS.

I suspect also that when in 2.6.27 my Samba shares are not accessible either, but I can't test that at the moment (I don't have the Windoze laptop for which I set up the shares for a couple of days).

I have tried every combination of firewall on or off (I turned the firewall off with "service iptables stop" - Is that sufficient?) and Selinux in enforcing and in permissive modes, on both the client and the server.

Interestingly, when Selinux is in permissive mode on the server, accessing one of the exported directories from the client no longer causes the terminal window (or Nautilus) to hang, but merely shows the directory as empty.

Reverting to 2.6.26 on the server allows everything to work normally with firewall on or off, Selinux in either enforcing (which is what I normally use) or permissive mode.

I normally try to keep up with all updates from Fedora, but it appears that I am stuck on 2.6.26 for the moment.

Have there been any filesystem or security changes in kernel 2.6.27?

With thanks - but tearing my hair out here...

Mark
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Postby Ram » Wed Dec 17, 2008 11:11 am

Another thought do you have IPv6 enable ?

Here's a link on how to disable it

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Postby Arthur_Dent » Wed Dec 17, 2008 11:52 am

Good thinking Ram!

But no... Just tried it. Folled the instructions in that article, rebooted into 2.6.27 and still the same problem.

Sigh... Back to 2.6.26....

Any other ideas?

I do appreciate your help

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Re: NFS and Kernel 2.6.27*

Postby Ram » Wed Dec 17, 2008 12:51 pm

Arthur_Dent wrote:The client IP is correctly listed in /etc/exports on the server.



Try using a wild card * instead of the IP, I'm but can't remember why, I had an issue with using IPs or hostnames when I setup my current server.

Just noticed that I'm only using NFSv2 (need to recheck my setup, YaST as NFSv4 selected as default, can't remember changing it) for the portmapper and your using 2,3 and 4.

Not sure what rquotad is, will research it.

Also the different kernels are using different ports for status but they don't seam to be fix so may not be an issue.

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