From: David Greaves <david@dgreaves.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] LVM2 seems to chop performance by 33%
Date: Mon, 14 Jun 2004 14:24:56 +0100 [thread overview]
Message-ID: <40CDA728.4080902@dgreaves.com> (raw)
In-Reply-To: <40CD910A.9040605@ist.utl.pt>
Miguel Cabe�a wrote:
> 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.
No, I didn't
hmm... man blockdev
useful - new to me :) Not seen it on any googling to do with lvm.
I'll try this later when it's idle - thanks for the suggestion.
I do already have
Read ahead sectors 100
in the lvdisplay
yet blockdev --getra /dev/video_vg/video_lv
reports 256 (and, to be sure --getss says 512byte sectors)
Why is this different?
David
prev parent reply other threads:[~2004-06-14 13:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-10 14:25 [linux-lvm] LVM2 seems to chop performance by 33% David Greaves
2004-06-10 15:05 ` Stuart Harper
2004-06-10 15:31 ` Chris Croswhite
2004-06-10 15:34 ` David Greaves
2004-06-10 16:30 ` Clint Byrum
2004-06-20 18:17 ` David Greaves
2004-06-20 19:53 ` Alasdair G Kergon
2004-06-21 9:55 ` David Greaves
2004-06-14 11:50 ` Miguel Cabeça
2004-06-14 13:24 ` David Greaves [this message]
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