RAID1 read balancing

RAID1 read balancing

[Petru Paler]

Hello,

For a RAID1 array built of two disks on two separate SCSI controllers,
are the reads balanced between the two controllers (for higher speed) ?

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Petru Paler, mailto:ppetru@ppetru.net
http://www.ppetru.net - ICQ: 41817235
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Re: RAID1 read balancing

[Arjan van de Ven]

In article <20010211161242.A949@ppetru.net> you wrote:

> For a RAID1 array built of two disks on two separate SCSI controllers,
> are the reads balanced between the two controllers (for higher speed) ?

With the current RAID1 setup, you will NOT get a speed increase for
single-threaded, sequential reading programs (read: benchmarks like hdparm
and tiobench)[1]. You will get improvents in all other cases.

Greetings,
   Arjan van de Ven


[1] This can be fix by a 10 line patch, however this changes the on-disk
layout.
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RE: RAID1 read balancing

[Jorge Boncompte (DTI2)]

    Hi!

    Could you provide an URL to that patch? I would like to test it.

    Regards.

    -Jorge

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DTI2 - Desarrollo de la Tecnología de las Comunicaciones
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----- Mensaje original -----
De: "Arjan van de Ven" <arjan@fenrus.demon.nl>
Para: "Petru Paler" <ppetru@ppetru.net>
CC: <linux-kernel@vger.kernel.org>
Enviado: lunes, 12 de febrero de 2001 10:34
Asunto: Re: RAID1 read balancing


> In article <20010211161242.A949@ppetru.net> you wrote:
>
> > For a RAID1 array built of two disks on two separate SCSI controllers,
> > are the reads balanced between the two controllers (for higher speed) ?
>
> With the current RAID1 setup, you will NOT get a speed increase for
> single-threaded, sequential reading programs (read: benchmarks like hdparm
> and tiobench)[1]. You will get improvents in all other cases.
>
> Greetings,
>    Arjan van de Ven
>
>
> [1] This can be fix by a 10 line patch, however this changes the on-disk
> layout.
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> Please read the FAQ at http://www.tux.org/lkml/
>

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