Mounting filesystems in RHEL is pretty straightforward and easy. Occasionally, however, you will not want the filesystem to remain mounted all the time, but rather to automatically mount for a set period of time only when it is needed. Because of networking overhead, and the general unreliability of networks, NFS mounts are a good example of when this can be especially useful.
In order to manage the automatic mounting and unmounting of filesystems on RHEL, we use the Automounter service. Here is how.
First, The main configuration file is “/etc/auto.master”. It should look something like this:
#
# $Id: auto.master,v 1.3 2003/09/29 08:22:35 raven Exp $
#
# Sample auto.master file
# This is an automounter map and it has the following format
# key [ -mount-options-separated-by-comma ] location
# For details of the format look at autofs(5).
#/misc /etc/auto.misc --timeout=60
#/misc /etc/auto.misc
#/net /etc/auto.net
Let’s assume that we want to set up an NFS mount on “/misc/backups”. We would first create an entry in this file that looks something like this:
/misc /etc/auto.misc --timeout=120
This tells the autofs service that we want to use it to manage mounts from within “/misc”, that the configuration file is “/etc/auto.misc”, and that it should disconnect after 2 minuets of inactivity.
Now, let’s edit the “/etc/auto.misc” file. The file has three columns: the mount point from within the /misc directory, the options for mounting the filesystem, and the filesystem to be mounted. It also includes the remote server’s name since we are using NFS. It should look something like this when you are done:
#
# $Id: auto.misc,v 1.2 2003/09/29 08:22:35 raven Exp $
#
# This is an automounter map and it has the following format
# key [ -mount-options-separated-by-comma ] location
# Details may be found in the autofs(5) manpage
cd -fstype=iso9660,ro,nosuid,nodev :/dev/cdrom
backups -rw,soft,intr remoteservername:/path/to/nfs/export
# the following entries are samples to pique your imagination
#linux -ro,soft,intr ftp.example.org:/pub/linux
#boot -fstype=ext2 :/dev/hda1
#floppy -fstype=auto :/dev/fd0
#floppy -fstype=ext2 :/dev/fd0
#e2floppy -fstype=ext2 :/dev/fd0
#jaz -fstype=ext2 :/dev/sdc1
#removable -fstype=ext2 :/dev/hdd
Next, we create the directory for the mount point in /misc:
# mkdir /misc/backups
And finally we restart the autofs service:
# service autofs restart
That should pretty much do it. If you don’t have autofs configured to start up, you can use chkconfig to enable it. “/misc/backups” will now be mounted whenever a user or process attempts to access data on it, and it will be automatically disconnected after 120 seconds of inactivity. Last, but not least, you can always confirm that it is running with the “service” command:
# service autofs status
As always, change the details to match your own requirements.
About a year ago I was looking for just such a mechanism, but I never found out about autofs. What I did was put “0 * * * * /bin/mount -a -t nfs” in root’s crontab. It’s ugly, and I think I’ll replace it with autofs.
I’m glad it was helpful Mike… By the way, what happened to your blog?
Thanks!!
My wife is much happier about editing our website now!