Re: Very slow LVM performance

[Stan Hoeppner <stan@hardwarefreak.com>]

Arcady Genkin put forth on 7/11/2010 10:46 PM:

>  lvcreate -l 102389 vg0

Should be:

lvcreate -i 10 -I [stripe_size] -l 102389 vg0

I believe you're losing 10x performance because you have a 10 "disk" mdadm
stripe but you didn't inform lvcreate about this fact.  Delete the vg, and
then recreate the vg with the above command line, specifying 64 for the stripe
size (the mdadm default).  If performance is still lacking, recreate it again
with 640 for the stripe size.  (I'm not exactly sure of the relationship
between mdadm chunk size and lvm stripe size--it's either equal, or it's mdadm
stripe width * mdadm chunk size)

If you specified a chunk size when you created the mdadm RAID 0 stripe, then
use that chunk size for the lvcreate stripe_size.  Again, if performance is
still lacking, recreate with whatever chunk size you specified in mdadm and
multiply that by 10.

Hope this helps.  Let us know.

-- 
Stan