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Date: Mon, 14 Jun 2004 12:50:34 +0100
From: "=?ISO-8859-1?Q?Miguel_Cabe=E7a?=" <cabeca@ist.utl.pt>
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Subject: Re: [linux-lvm] LVM2 seems to chop performance by 33%
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To: LVM general discussion and development <linux-lvm@redhat.com>

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 Cabe=EF=BF=BDa