Which better - PERC 3/DC or 3/Di?

Chris Chabot chabotc at reviewboard.com
Mon Nov 26 07:27:00 CST 2001


Some part is due to the driver.. being NT derivative (or as arjan
described it 'a piece of NT shite'), can not be helpfull for the
performance.

Secondly, somehow the block layer doesnt fully like this driver (cause
of the above?). Since the 2.4.11 release, i have notice a nice speed
increase in the Perc 3/Di performance, though not nearly to 'expected'
performance. The aac-raid driver was the same, so some block layer
changes caused this to happen.

Last, Domsch pointed out, that their suspission is that for a large part
the performance problems are caused by the firmware on the cards.
Internaly they are testing newer versions, which "Show considerable
performance improvements under linux".

However the bottom line is, that my current PE 2550's @ $6000 + a pop,
with 4x 10k rpm u160 disks are allowing me to read with speeds that only
_just_ outperform a single 10k rpm disk on a normal controller (tried
all raid combinations, 0, 10, 5. Results are always very poor and around
single disk speed).

I think Alan Cox said it best when he said:
"Removed raid card, pluged disks to normal scsi controller, setup
software raid. Result: a much faster and more stable system".
(this was in regards to an ami card, however the same can definatly be
said for the adaptec cards).

not a bad result for the amount of money we have put down for these
systems <grin>

I gues my real bottom line would be 'Buy an IBM or posible a Compaq
server if you need raid performance' ? ;-)

	-- Chris

On Mon, 2001-11-26 at 14:09, Arjan van de Ven wrote:
> "Hubbard, David" wrote:
> > 
> > The Adaptec cards are great if you want to get 5 MB/sec writes
> > out of $3000 worth of 10,000 rpm disks!  Seriously, they
> > are that good!!  :-)
> > 
> 
> I have reason to believe that at least some of this is due to the
> driver....
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