[linux-lvm] LVM2 seems to chop performance by 33%

[Miguel Cabeça]

Hi,

> I didn't think lvm2 had such a big performance hit?
>
> 65Mb/s on the raid5 device
> 44Mb/s on the lv
>
Did you try to ajust the read ahead with blockdev on the LV itself?

# blockdev --setra XXXX /dev/sda  (raid5 device, just for comparisson)
# blockdev --setra XXXX /dev/vg/lv (lv)

Try some values for the readahead. On my system I use 2048.

Best regards

Miguel Cabeça