Re: ORBS Elevator...

From: Rik van Riel (riel@conectiva.com.br)
Date: Sat Jul 29 2000 - 14:16:51 EST


On Sat, 29 Jul 2000, Andre Hedrick wrote:

> It is one platter and a pair of heads.
> I will know the discrete track/sector arrangements.
> This is the first case where the "elevator" an be used as a strong boost.

How about RAID1 devices?

In that case we have the data replicated over (usually) 2
disks and we can optimise the reading of the data in such
a way that seek times on both disks are minimised, instead
of dividing the requests over both disks randomly and
hoping that the elevator code below can deal with it.

Btw, if we want to do better IO clustering, we should probably
start doing IO clustering on *higher* layers. Currently we just
feed the elevator a random subset of the blocks that are to be
written and we hope that it's good enough...

regards,

Rik

--
"What you're running that piece of shit Gnome?!?!"
       -- Miguel de Icaza, UKUUG 2000

http://www.conectiva.com/ http://www.surriel.com/

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