[Mac-NT] Re: Macintosh Hardware Controllers for RAID Arrays

Daniel L. Schwartz(expresso[at]snip.net)
Sat, 20 Nov 1999 11:16:23 -0500

From: "Daniel L. Schwartz" <expresso@snip.net>

POSTED TO THE WINMAC LIST DUE TO NEW INFO...

        Dear Adam,

        You're spot-on about lack of Mac support for PCI Option Card hardware RAID
controllers. The vendors offering "Mac" solutions fall into two categories:

        1) SCSI - SCSI RAID controllers: These are platform (OS & file system)
independent, and generally cost more... But are more robust since there is
a dedicated hardware RAID controller. Check out Infortrend's offerings
<http://www.infortrend.com>, too. The downside is that you are limited to
the SCSI speed of the host controller in the Mac;

        2) Software RAID using the Mac to make the RAID calculations. Sometimes
these come with a bunch of drives in a case to "add value." These are OK
for RAID Level 0 (striping), but are no good for RAID level 5 (striping
with distributed parity);

        The third option, a PCI Option card that has a hardware RAID CPU or ASIC
and can cram data on a 32 bit or 64 bit PCI bus, is not available for the
Mac. When I was at MacWorld in NYC in late July I spoke to the senior
Adaptec rep about porting the AAA-133 to the PCI Mac, and he told me that
was the single largest request. That's the good news. The bad news was that
it was still AdapCrap (or "InepTec") - Take your pick).

        I've had conversations with the folks at the US office of Infortrend, and
they seem interested in a Mac port.

-> BUT, with any PCI Option Card hardware RAID controller to be ported to
the PCI Mac, numerous hurdles need to be overcome. Most importantly is the
lack of x86 emulation needed for most every PCI hardware RAID controller
for low level setup. [You see this on x86 boxes when it'll say "Hit
<Ctrl-A> to enter Setup."] This feature - BIOS emulation - is included on
*almost* every RISC platform (through AlphaBIOS or equivalent ARC (Advanced
RISC Consortium) , for example) except one: The beloved, non-standard PCI
PowerPC Mac.

        Because there is no ARC console on the PCI Power Mac, setting up a
complicated RAID controller will require not only new drivers - Which in
itself is crazy proposition due to the ever-changing MacOS breaking drivers
with almost every iteration - need to be written, but also a completely
built-from-scratch GUI application to set up and control the array.

        [There IS an alternative, but many Mac-only users would have trouble
swallowing this: Set up the array on a PC, then move everything - PCI card
and disk drives - to a PCI Mac. Then, it would present itself as a single
logical drive, ready to be partitioned and initialized to HFS or HFS+. Even
a basic 486 with PCI slots, BIOS support for PCI bridging (PCI 2.0 spec)
and 4 MB of RAM & video card would suffice for this duty, since it's only
used for BIOS setup and flash upgrades from floppy - No hard drive needed.]

 -----

        Using a hardware RAID controller for the Mac would indeed be a big help,
providing a big performance boost and clearing a major I/O bottleneck not
only for traditional server applications but also high performance graphics
and desktop video workstation duty. RAID Levels 3 & 4 (Striping with a
dedicated parity HDD; Level 3 on the byte level, Level 4 on the block
level) are especially suited to high performance workstation duty,
providing not only the raw speed of RAID Level Zero (pure striping but zero
fault tolerance) but also the safety margin of being able to lose one (or
more) hard drives yet still eliminate data loss.

        Cheers!
        Dan

At 03:41 PM 11/20/99 +1000, you wrote:
>I read your discussion on the "Windows-MacOS Cooperation List". I followed
>the links provided and obtained some useful information. This subject is
>hard to find information on.
>
>Excuse my ignorance but I hope you could claify some stuff for me.
>
>The card I am looking for is a Dual Ultra 160 with hardware raid controller.
>( This may not exist )
>
>1. What are the hardware controllers out ther for the mac ?
>
>2. I have found
> 1. DPT SmartRAID VI, Compact PCI Ultra160 SCSI RAID Controller.
> (Intel i960 based ONLY SINGLE CHANNEL)
>
> 2. ADAPTEC PowerDomainŽ 39160 Ultra 160/m
> ( Dual Channel NO HARDWARE RAID )
>
> 3. MYLEX AcceleRaid 352
> (Dual channel, hardware raid i960RN 100mhz, NO MAC DRIVERS)
>
> eXtremeRAID 2000
> (Quad Channel, hardware raid StrongArm 233mhz,NO MAC DRIVERS)
>
>(note: DPT and Adaptec are merging)
>
>Thanks for your help.
>
>Adam

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