2001-02-11 14:13:19

by Petru Paler

Subject: RAID1 read balancing

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) ?

--
Petru Paler, mailto:[email protected]
http://www.ppetru.net - ICQ: 41817235

2001-02-12 09:34:39

by Arjan van de Ven

Subject: Re: RAID1 read balancing

In article <[email protected]> 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.

2001-02-12 11:35:23

by Jorge Boncompte [DTI2]

Subject: RE: RAID1 read balancing

Hi!

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

Regards.

-Jorge

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Jorge Boncompte - T?cnico de sistemas
DTI2 - Desarrollo de la Tecnolog?a de las Comunicaciones
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----- Mensaje original -----
De: "Arjan van de Ven" <[email protected]>
Para: "Petru Paler" <[email protected]>
CC: <[email protected]>
Enviado: lunes, 12 de febrero de 2001 10:34
Asunto: Re: RAID1 read balancing


> In article <[email protected]> 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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