Sunday, August 10, 2008

Auto mount for Red Hat Derivative Distributions

In my previous 2 posts we setup NFS client and NFS server. There is another way of setting up the client so that the mount is temporary and only made if and when the share is required, this way speeds up your boot process as the NFS share will only mount if and when you need it and not during boot time. A mounted file system or share will always stay mounted until you umount it, this can cause problems with NFS especially if your connection to your server is lost as your machine would not have umounted the share.
Auto mounter to the rescue.
automounter will mount your shares on a temporary basis, as and when you need them. it will also umount your shares automatically after an interval of inactivity (60 seconds by default).
to setup automounter edit your /etc/auto.misc file and add the following

name_of_share -fstype=nfs

were is your nfs share on the server
name_of_share can be any name you choose, this will just specify the directory name you need to change to to automount the share.

save your /etc/auto.misc

now your /etc/auto.misc file is informed by the information in your /etc/auto.master file (you shouldent have to change anything in there but to understand how automount works it is a good idea to look inside the file.
if you look inside your /etc/auto.master file you will see 2 entries that look like so
/misc /etc/auto.misc
/net -hosts

this informs your auto.misc file to temporally mount your share under /misc
and your share will also be browsable under /net

you will need to ls /net/ to see the shares on your server

or cd into /misc/name_of_share to access the share (even though you don't see the server or the share under /misc and /net they will appear only when you cd into them

the mount will stay mounted whilst the directory is in use and then for 60 seconds longer after inactivity The mount will disappear you will need to cd or ls the sharename to access it again.

if you type cd .. so that you are in the /misc folder and then type ls again you will now see your share, but it will only be there for 60 seconds and then it will automatically umount and dissapear

if you wanted to change the place that the automounts take place from /misc to some other directory of your choice then you will need to edit your /etc/auto.master file and change /misc to whatever you like. Once saved restart the automounter service.
/etc/init.d/autofs restart
for your changes to take effect.

Debian based distributions uses different tools to accomplish the same, I will cover the debian tools in a future post.

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