striping

[Jose_11]

Hi,
Is it recommended/not-recommended to do striping on /var on 2 disks ?
Can I do striping to root filesystem ?

Thanx in advance

[Stefan Farrelly · Accepted solution]

Stripe the root filesystem ?, well, good question.

Firstly, /, swap and /stand (lvol1,2,3) must be contiguous - which means you cant stripe them at all. But you could possibly stripe /opt, /usr and /var. However, I would not recommend it for the following reasons;

1. If possible, keep /var, /opt and /usr on the boot disk only. This makes diagnosis of problems and resolution much easier. Adding a 2nd disk (for the stipe) would make recovery more difficult.
2. If you need to later, extending a stiped filesystem is more difficult than non-striped.
3. If you have some part of /var which is being hammered by some application then you could look into creating a symbolic link of the directory to a filesystem elsewhere on a non root disk to alleviate the problem. Or increase the unix buffer cache to improve I/O times (if you have memory available).

I wouldnt recommend it unless you have a chronic performance problem with /var and no other options.

[Joseph C. Denman]

I agree with Stephan. I would not stripe your primary os filesystems, and as stated, you can't stripe a few of them. If var is giving you trouble by being hit by some app, you could also move it to a different vg. /var does not have to remain on the root vg.

...jcd...

[Tim D Fulford]

Joe

I agree with both of the above, BUT...

There is some performance advantages in mirroring (if you have not already done so). When reading from mirrored disks the disk where the head is closest should be chosen. This will reduce the ammount time the OS needs to wait for the data. you might see the service times drop from say 10ms to 9 or 8ms (for reads).

Just a thought

Tim

[melvyn burnard]

Basic rule of thumb, used when teaching ServiceGuard course:
keep root VG simple, do not stripe, try to keep it all on one disk, use MirrorDisk/UX or RAID, and havean Ignite/UX make_recovery tape of vg00.