LVM performances...

[Andrea Giuliano]

Hi,

I'm using LVM2 on FC2 without problems, after a long experience with
LVM1 on FC1. But anyway I have a question: is there an optimal way to
choose the size of physical volumes, volume groups and logical volumes?

LVM allows you to choose these parameters as you like, but your choice
could well be incompatible with hardware parameters.

For instance, one could define a logical volume for, say, /tmp. If this
logical volume spans several cylinders, a lot of traffic on /tmp (as
when you compile large programs like the kernel) may result in much more
heads movements than those that would happen if the logical volume only
span one cylinder.

Sorry, maybe "cylinder" should be replace by "plates", or "sectors"...
I'm not very familiar with disk hardware. But I hope you got the point.

I had a look around, but till now I dind't find any reference to
performance in LVM documentation, except for an explicit warning about 
doing striping on a single hard disk (I easily can figure out why).

Any hints?

Best regards.

-- 
Andrea Giuliano, Ph. D.
ICCU - Istituto Centrale per il Catalogo Unico
Viale Castro Pretorio 105, Rome - ITALY
Tel. +39064989509, Fax +39064059302