Re: IDE hotplug support?

["Jeff Nguyen" <jeff@aslab.com>]

You can get a sustained read speed of 80MB/s on the Adaptec 2000S
Zero Channel RAID with 7 drives (RAID-5). But the sustained write
speed is only around 32MB/s.

On the other hand, the 3Ware Escalade 7850 can sustain a read speed
of 130MB/s with 8 drives (RAID-5). The write speed is 30MB/s.

Jeff

----- Original Message -----
From: "Jakob Østergaard" <jakob@unthought.net>
To: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
Cc: "Martin Dalecki" <dalecki@evision-ventures.com>; "Pavel Machek"
<pavel@suse.cz>; "Roy Sigurd Karlsbakk" <roy@karlsbakk.net>;
<linux-kernel@vger.kernel.org>
Sent: Thursday, May 02, 2002 2:13 PM
Subject: Re: IDE hotplug support?


> On Thu, May 02, 2002 at 09:26:38PM +0100, Alan Cox wrote:
> > > >=20
> > > > 8 x 130MBy/s >>>> PCI bus throughput... I would rather recommend
> > > > a classical RAID controller card for this kind of
> > > > setup.
> > >
> > > Because RAID controllers do not use the PCI bus ???    ;)
> >
> > The raid card transfers the data once, software raid once per device for
> > Raid 1/5 - thats a killer.
>
> For RAID-1 it's a killer (for writes), I agree.
>
> But I really doubt it would be so horrible for RAID-5 - after all, it's
only
> one extra block (the parity block) for each N-1 blocks written (for an N
disk
> RAID-5).  The penalty should be less, the more disks you have in the
array.
>
> But seriously, has anyone out there ever seen a hardware RAID controller
with
> a *sustained* RAID-5 thoughput of more than 60 MB/sec ?   Not that I think
it
> is impossible, but I've never heard about it.  Enlighten me, please, and
not
> with marketing numbers...
>
> >
> > > By the way, has anyone tried such larger multi-controller setups, and
t=
> > > ested
> > > the bandwidth in configurations with multiple PCI busses on the board,
=
> > > versus a
> > > single PCI bus ?
> >
> > With 2.4 yes. With all the 2.5 changes no.
>
> Did you get any speedup ?  Were you close to PCI bus saturation in the
one-bus
> scenario ?
>
> --
> ................................................................
> :   jakob@unthought.net   : And I see the elder races,         :
> :.........................: putrid forms of man                :
> :   Jakob Østergaard      : See him rise and claim the earth,  :
> :        OZ9ABN           : his downfall is at hand.           :
> :.........................:............{Konkhra}...............:
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