mount a whole partition over NFS

sycamorex · 07-06-2008, 01:05 PM

I don't have problems mounting a directory, however I'd like to mount a whole data partition /dev/sdb1 (320GB) over NFS

When I try to put it in /etc/exports

Code:

/home   192.168.1.107(rw)
/dev/sdb1 192.168.1.107(rw)

Code:

[root@f9-sda10-105 xtd8865]# /usr/sbin/exportfs -ra
exportfs: Warning: /dev/sdb1 is neither a directory nor a file.
     remote access will fail

Normally /dev/sdb1 is mounted on one of my home directories on the remote machine, however, when I mounted my /home over NFS, and checked /home/username/data (the directory that /dev/sdb1 is locally mounted on) and it seems to be empty. Can it be a permission problem?

thanks

sycamorex · 07-06-2008, 01:11 PM

Quote:

Normally /dev/sdb1 is mounted on one of my home directories on the remote machine, however, when I mounted my /home over NFS, and checked /home/username/data (the directory that /dev/sdb1 is locally mounted on) and it seems to be empty. Can it be a permission problem?

Ok, sorted

Then my next question:

the entry in /etc/exports is:
/home/username/data1 192.168.1.105(rw)

how can I add it to /etc/fstab on the client machine?

thanks

Mr. C. · 07-06-2008, 01:55 PM

man fstab

Sample:

Code:

server:/home/username/data1   /mnt/SOMEDIR   nfs    NFSOPTIONS_HERE 0 0

Suit to taste.

sycamorex · 07-06-2008, 02:07 PM

I was mostly concerned with the nfs options. I have decided on rw,setuid.
Now I'm reading about autofs (however, in my case one mount will not make a big difference for my system)

thanks

Mr. C. · 07-06-2008, 02:09 PM

The autofs automounter allows the file system to be mounted upon access.
It may be that what you really want is mount at boot time.

Which of these ?

The options you chose for NFS mounts depends upon your usage scenarios.

sycamorex · 07-06-2008, 02:28 PM

Although I haven't noticed any visible impact on the performance (mounted via fstab) even with some additional network traffic, I might go for autofs. The reason being that the nfs client is connected to the router via wireless which is controlled by network manager. As the partitions are mounted at an early stage of the system boot up, it will probably fail to mount, as the laptop gets connected to the internet in the GUI environment.

Mr. C. · 07-06-2008, 02:39 PM

There is no difference in performance relative to autofs v. fstab mounts. What mechanism performs that mount is irrelevant.

You can set your fstab to retry in the background to not hold up other mounts with the bg option, or noauto to not automatically mount upon during boot (eg. mount -a). This allows you to mount -a -t nfs later.

FYI: partitions are not mounted - file systems are.

sycamorex · 07-06-2008, 03:12 PM

Quote:

There is no difference in performance relative to autofs v. fstab mounts. What mechanism performs that mount is irrelevant.

Well, not according to redhat manuals on NFS

:

Quote:

One drawback to using /etc/fstab is that, regardless of how much you use that mounted filesystem, your system must dedicate resources to keep that mount in place. This is not a problem with one or two mounts, but when your system is maintaining mounts to a dozen systems at one time, overall system performance can suffer. An alternative to /etc/fstab is to use the kernel-based automount utility, which will mount and unmount NFS filesystems automatically, saving resources.

HOwever, as I would have only one NFS mount, it shouldn't matter.

Quote:

...noauto to not automatically mount upon during boot (eg. mount -a). This allows you to mount -a -t nfs later

I will try it

thanks

Mr. C. · 07-06-2008, 03:24 PM

Quote:

Originally Posted by sycamorex

Well, not according to redhat manuals on NFS

:

I think perhaps there is a misunderstanding. What is the reference?

sycamorex · 07-06-2008, 03:37 PM

http://www.redhat.com/docs/manuals/l...nt-config.html

But anyway, I've modified the fstab entry and used the bg option - it's really clever to
exit with a zero exit code and to keep trying to mount it in the background.

Mr. C. · 07-06-2008, 03:55 PM

The performance topic you see is about very large environments where dozens or hundreds of mounted and cross-mounted directories are maintained. Each mount consumes a certain amount of memory in the mount table, and a certain amount of network bandwidth to maintain the mount. For anything less, you have nothing to be concerned about.

Automounting has pros and cons, which you'll discover soon enough.

sycamorex · 07-06-2008, 04:15 PM

Yeah, that's what I meant - it wouldn't matter for my setup

Actually, what I might do is to have 2 nfs mounts - one via fstab, the other one via automounting.
Just for the sake of learning and comparing...

Mr. C. · 07-06-2008, 04:56 PM

Sounds fine. Just avoid accidental overlapping mounts (eg. manual mount + automount on same mount point).

Just as an FYI, fstab is simply a convenience table for mount(8), fsck(8), dump(8) and a few other utilities. There are no special properties about it. I mention this for those reading who think there is something "magical" about /etc/fstab (vs. manual mount, fsck, etc.).