Thread: IDE RAID
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Old September 19th 04, 11:28 PM
Ron Reaugh
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"Leythos" wrote in message
...
In article ,
says...

"Leythos" wrote in message
...
In article

,
says...
The Promise chip on the mobo is nothing more than a fancy ATA

controller
chip with NO significant RAID functionality on it. All on mobo

Promise
RAID
is firmware/software in x86 code hosted by the host's x86 CPU.

I would be interested in seeing where you get this information from.

In
reviewing the Promise RAID 0/1 controller on the motherboard of the

ASUS
PC-DL Deluxe board, I've only seen that the "driver" is a stub



Nope. No clue where you see this as there is full driver support there

in
two different flavors. One RAID and one NOT.

that
allows the OS to recognise the controller (much like the SCSI RAID
Controllers that we use in HP or Compaq servers).


Any OS install requires a F6 driver load just like any other RAID card

that
the OS doesn't already know about.

All my assertions are obvious once one thinks about it. Look at the

specs
for a real HW RAID like a 3Ware and notice the onboard uP.

Look at the SATA card:

http://www.promise.com/product/produ...26&familyId=3#

Look at its nearly identical sibling RAID card:

http://www.promise.com/product/produ...07&familyId=2#

Both use the same Promise SATA controller. The only significant

difference
is the onboard firmware chip, which contains x86 code. One has RAID
functionality and the other doesn't.


I'll contact promise - I'm interested to really know if the OS/Driver
has to make two writes in RAID-1


It does.

or if the firmware handles it on it's
own.


The firmware is hosted on the x86 host CPU so if x86 hosted firmware does it
then it PROVES my point.

Have you ever investigated the speed of code running from a ROM which is
where firmware is held vs code in RAM were device drivers are held? Ever
hear of the concept of shadowing the video BIOS or other BIOS segments in
RAM and what that's all about?

Since I have a large number of PC-DL servers with Dual 250GB SATA
in RAID-1 mode it will be interesting to see their response.


Why? You are chasing a ghost.

The percentage of writes is usually small so that extra host overhead in
RAID 1 is not very important. To avoid it one must use full hardware RAID
like 3Ware. To avoid it the RAID controller must have onboard buffering and
there is none for the Promise nor other onmobo [S]ATA RAID solutions. All
are firmware/software RAID and all do two host I/O bus writes for RAID 1
writes.

I use P4C800-E Dlx mobos on some SBS2003 sites of mine. I like W2K3's
intrinsic SW RAID 1. I don't even bother with the onmobo RAID but just use
the OS's intrinsic RAID 1. There is NO performance disadvantage compared to
onmobo SW/firmware RAID 1. Little performance would be gained by using a
$350 3Ware card for true HW RAID 1 here but RAID 5 with it's parity calcs is
a horse of a different color. Then I do 3Ware or SCSI HW RAID 5 with
Fujitsu MAS3735s.