topic why LVM performance lower than ext3 in Operating System - Linux

why LVM performance lower than ext3

richeal75 — Sat, 22 Oct 2005 06:06:58 GMT

hardware: HP Proliant DL585 + MSA1500

Use same Lun on MSA1500:

LVM: copy 10GB file , need 10mins
ext3: copy 10GB file , need 5mins

I want to confirm if LV IO performance lower
than ext3 ?

How can I tune LVM IO performance ?

thanks for your help in advance !

Re: why LVM performance lower than ext3

Slawomir Gora — Sat, 22 Oct 2005 10:29:59 GMT

Hi,
ext3 this is filesystem type and LVM it is volume manager - you can't compare this.

What type of FS you have on LV created in LVM group ?

Re: why LVM performance lower than ext3

richeal75 — Sat, 22 Oct 2005 23:02:31 GMT

Hi Gora ,

Thanks you help!

LVM FS type = ext3

my test :

dd if=/dev/zero of=1.out bs=1k count=10240k
dd need only 2mins

but I cp 1.out 2.out
cp need about 10mins

so i tune LVM readahead as below:

lvcreate -r 120 -L 100GB vg1

but cp 10GB still need 10mins

Re: why LVM performance lower than ext3

Claudio Cilloni — Mon, 24 Oct 2005 03:51:49 GMT

hi,

the dd command you are using doesn't read data from disk, but it only writes.
the cp command instead reads and writes on the same disk, and this is obviously much slower.
these are two different activities, so it isn't a good test.

ciao
Claudio