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umount nfs cdrom

hpuxhelp
Regular Advisor

umount nfs cdrom

when view /etc/mnttab , see the nfs mount for cdrom.
According to the man page, can't manually edit this file. any suggestion on delete this line?
problem : nfs server still not responding...
in /etc/fstab, there are no present of nfs mount
already stop all of the nfs daemon (server, client and core) in addition, also edit the rc.config.d nfsconf file...
6 REPLIES
MANOJ SRIVASTAVA
Honored Contributor

Re: umount nfs cdrom

Hi

If you get that message then it is better to reboot the server and see that the nfs is prperly umounted . An improer umount results in such errors . This will also result in an incomplter list os bdf etc bcoz it check for the mounted partions . You canoot edit mnntab , all you can do it rename it and then do a mount -a which will recreate the mnntab , but this will not help nfs server not responding message . yopu will have to reboot the server .



Manoj Srivastava
KapilRaj
Honored Contributor

Re: umount nfs cdrom

Is that cdrom mount point exists on your box. do as follows,

mv /etc/mnttab /etc/mnttab.old
mount -a
lsof "mount point of cdrom"
note down the processes accessing that file
do a ps -ef |grep for those process ids & terminate them....

do
/sbin/init.d/nfs.client stop # I assume there are no nfs mounted directories if there umount them for a while....

/sbin/init.d/nfs.client start


Cheers,

kaps
Nothing is impossible
Rory R Hammond
Trusted Contributor

Re: umount nfs cdrom

This can happen when you hard mount a nfs filesystem. the default is to hard mount. If you soft mount nfs you can unmount "stuck" filesystems without rebooting.



There are a 100 ways to do things and 97 of them are right
hpuxhelp
Regular Advisor

Re: umount nfs cdrom

what is the different between a hard and soft mount ?
Paul Sperry
Honored Contributor

Re: umount nfs cdrom

There are two flavors of NFS mounting, hard and soft. A 'hard' mount is the way it was originally intended to work, and is achieved either by a line in /etc/fstab (which lists the disks mounted at boot time, both local and over NFS) or by direct use of /etc/mount . A 'soft' mount is a disk that was mounted via the automounter.
Rory R Hammond
Trusted Contributor

Re: umount nfs cdrom

I have never heard of the automount theory. Soft and Hard option have been around for along time. At least on one of my System 5 unix's in the 90's before automount was available on it. The man page
"man mount_nfs". Has a section concerning hard vs. soft It seem to confuse more than clarify:

Hard vs. Soft
File systems that are mounted read-write or that contain executable files should always be mounted with the hard option. Applications using soft mounted file systems may incur unexpected I/O errors.

To improve NFS read performance, files and file attributes are cached. File modification times get updated whenever a write occurs. However, file access times may be temporarily out-of- date until the cache gets refreshed. The attribute cache retains file attributes on the client. Attributes for a file are assigned a time to be flushed. If the file is modified before the flush time, then the flush time is extended by the time since
the last modification (under the assumption that files that
changed recently are likely to change soon). There is a minimum and maximum flush time extension for regular files and for directories. Setting actimeo=n sets flush time to n seconds for both regular files and directories.


My experience is that you get I/O errors via NFS when the remote system becomes unavailble (crash), Or the network goes down. How you use the NFS filesystem might determine how you mount it. The reason why I have been using (for years) the soft mount option is to avoid problems like you are experiencing. We have yet to receive catastrophic I/O errors via NFS. However most of my remote mounts are used for "READS" a few have low write activity.

Ror
There are a 100 ways to do things and 97 of them are right