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NFS-client (HP-UX 11.11) hangs....

 
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Danny Petterson - DK
Trusted Contributor

NFS-client (HP-UX 11.11) hangs....

Hi Masters!!

Problem - nfs-client on HP-UX hangs. I cant access the share from this particular server (works from all others though), all commands concerning this share (bdf, df -k, ls -l fuser -cu, fuser -ku etc) all hangs, and are IMPOSSIBLE to shut down with kill -9! Nothing happens.

Its an production-system, so I cant reboot it for some time. Shutting down with /sbin/init.d/nfs.client (and server), works (kind of....), but when I start it it hangs...

Any good idea would be appreciated.

Thanx in advance

/Danny Petterson
7 REPLIES 7
Steven E. Protter
Exalted Contributor

Re: NFS-client (HP-UX 11.11) hangs....

Shalom,

When nfs hangs like this sometimes only a boot can fix it.

Usually its caused by a loss of network connectivity.

The good news is there is evidence of the crime.

/var/adm/syslog/syslog.log

Should contain error messages thwt will help with diagnosis.

tail -f /var/adm/syslog/syslog.log

Then stop/start the client and see what happens.

Complete procedure should if possible be to stop the client, the nfs.server and nfs.core product and then start.

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Steven E Protter
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Danny Petterson - DK
Trusted Contributor

Re: NFS-client (HP-UX 11.11) hangs....

Thanx for your answer - Ive tried that, no-go!

Syslog does not stated anything interesting, just nfs-server responding/not-responding.

...just...dont....want....to...reboot....
Bill Hassell
Honored Contributor

Re: NFS-client (HP-UX 11.11) hangs....

No choice with older versions of HP-UX. Newer versions of NFS code will try to unhook the code from the rest of the filesystems. NFS is as reliable as your network, your routers, and your NFS server. So unless all of those items are more reliable than your production system, don't use NFS. You'll have to live with the hangs until you can reboot. Before you reboot, I would edit /etc/rc.config.d/nsfconf and turn off all the NFS features. Then look at non-realtime methods to share files until your NFS server can be made production quality.


Bill Hassell, sysadmin
V. Nyga
Honored Contributor

Re: NFS-client (HP-UX 11.11) hangs....

Hi,

I would check:
- network configuration: is the switch running the same config (10/100/1000 MBit HD/FD) - I wouldn't set it to automatic, but manual - both sides!
- could it be that a nfs directory is set, which disappeared? A server which is disconnected?

HTH
Volkmar
*** Say 'Thanks' with Kudos ***
Indrajit_1
Valued Contributor

Re: NFS-client (HP-UX 11.11) hangs....

Hi;

if NFS client hang, the only soluation is reboot the box.

But, there is temporary soluation. this is help you to run other command. for example, bdf, etc.. but you won't be able to access shared directoy from NFS server.

#ps -ef |grep -i syncer
#kill -9
#vi /etc/mnttab
comment the line for nfs
save and come out

#/sbin/syncer -s

#bdf (it would successfully work)

once u get the downtime, reboot the box.

all the best.

Cheers;
Indrajit
Never Ever Give Up
Dave Olker
Neighborhood Moderator
Solution

Re: NFS-client (HP-UX 11.11) hangs....

Hi Danny,

There are many things you can try to unhang an NFS client before resorting to a reboot. I wrote a technical paper that documents different methods of recovering from a hung mount point and possibly unmounting hung filesystems. The technical  paper is posted here:

http://docs.hp.com/en/3929/ForciblyUnmountingNFSFilesystems.pdf

This technical paper talks about different strategies available on systems prior to 11.23. One big benefit of running HP-UX 11.23 on NFS clients is the new forcible unmount feature. This allows you to use the "umount -f" command to forcibly remove a hung NFS mount point from the client without having to reboot the client.

Now, all that said, you may already have hosed yourself by using terminate -9 on the hung processes. Once you use terminate -9 it's very likely that these processes will not clean up their resources and exit in such a way that would allow you to unmount your hung filesystems.

The best advice I can give you prior to rebooting is to try to identify what is causing the stop responding . Is it one NFS server that isn't responding? Is it one specific mount point where all the biods are blocked trying to service? Is it one specific IP address of the server that isn't responding to requests? If it's any of those cases you might be able to fool the client into thinking the server/IP address is back on line again and get the hung processes to unblock (using the strategies outlined in the technical paper).

If they do unblock they should receive the terminate -9 signals you've sent and die. Whether they actually release the resources they were holding on the hung NFS filesystems is anyone's guess.

If this happens frequently in your environment you should consider upgrading to 11.23 to get the forcible unmount feature.

Regards,

Dave





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Danny Petterson - DK
Trusted Contributor

Re: NFS-client (HP-UX 11.11) hangs....

Hallo everyone!

Thanx for your replys. Havent found the right solution yet, but Im looking into it.

For som strange reason, the client-connection started to work again aftaer aprox. 6 hours, no change in load on the share, network or everthing, it just decided to access the share, without any anoying errors.

I might add, the NFS-server has several other clients connecting to the same share, none of them have experienced any problems.

But again, thanx alot for suggestions, whitepapers etc.

Yours
Danny Petterson