quickie - make lvol for /usr or not?

[Terry_63]

Just a quick question. Does anyone know if there are distinct advantages/disadvantages to mounting /usr, /opt/ and /tmp as seperate logical volumes as opposed to leaving them as part of / filesystem??

Thanks

Terry

[James R. Ferguson]

Hi:

Having separate mount points for /usr /opt and /tmp (from the root) is standard and desirable. The idea is to "allow" one file system to fill without impacting (stopping I/O) to another. More importantly, the segregation of mount points allows you to restrict user access to do system maintenance. This is particularly true for /usr when you want to drop to or boot up into single-user mode to do maintenance. Since /sbin is a directory of the root with "system" commands, you can (un)mount /usr independently, thereby restricting general system access and availability.

If you have Online JFS you can extend (or reduce) the size of file systems "on-the-fly". If you don't purchase the Online component of JFS (an option) then you must unmount file systems to expand them. There again, you want to be able to mount and unmount subsets of directories to accomplish the task.

...JRF...

[Terry_63]

Hi and thanx, but i should have clarfied my question a bit more really; our / is quite static (many of our s/w binaries are in seperate lv as are the home dirs). I understand having seperate lvols for them is easier for sys-admin, but is it significantly beneficial in terms of security? (if its no trouble, could u explain why having /usr mounted in single-user mode is insecure?)
Thanks again

[CHRIS_ANORUO]

Hi Tahir,

You can move /usr to another disk, but for recovery purposes, IUX make recovery will see the root disk as 2 disks. My advise is to move /home, /var, and /opt to another disk and have /usr on the same disk as /(root).

[Victor BERRIDGE]

I keep vg00 (rootvg) as standard as possible, I mean there is only OS specific things on. in order to use Ignite without having to touch all other disks, so boxes that boot internal have vg00 internal and subsystems for the rest, I put software in separate lvols under /opt like /opt/oracle /opt/gnu ...
This makes maintenance easier (OS =>vg00)