View Full Version : RAID Advice

05-27-2001, 05:14 PM
This being my first RAID, im looking for scalability as well as speed, but I have a budget too.

My idea was to get the ATTO UL3S and a pair of Cheetas, stuffed into a Burly Quad bay, for a simple striped array to get wicked performance out of my BeigeG3 300, and later a G4 Sawtooth in about 6 months or so.

But then I was thinking maybe I could get a nice bonus in performance if I spend alittle more on the ATTO UL3D and duplexed the two drives, one per channel, with the intention of filling the box in with 2 more Cheetas in the following year.

Does any of this sound feasable? Perhaps there's a better option I haven't thought of?

Im also debating wether I should go with 10K ST318405LW Cheetas or the 15K ST318451LW. The 15K's look pretty slick, but the 10K's look similar, and cost allot less, seek time aside.

Again, I'm new to higher-end SCSI, and would love some feedback.

05-27-2001, 09:45 PM
If you want to do RAID right, and you can afford it, The ATTO UL3D and two Cheetah X15's are the way to go. On a single channel, one X15 gives you approx. the same throughput as two striped 10 K Cheetahs. There's more than just a 50% difference in rotational speed between these drive generations. You will also notice another performance jump with this rig when you migrate it to the faster system bus and Newer PCI controller on the G4 machines. You can't do any better at this time. I own a UL3D with two 10K's on it and a Miles2 with two X15's on it. Seems like it should be the other way around but I need them as they are.


05-28-2001, 01:38 AM
when you build your quad-bay Burly, there is no reason why you can't use a pair of GD7031 internal TPO ribbon cables, and put one X15 on each bus, striping across drives and buses. You will need a UL3D to proceed this way, but your future expansion will require nothing more than two more drives. Accordingly, this may be a fairly expensive way to start your array. (You will already have purchased all required cables and terminators and cooling units for four drives).

a more affordable way to begin, and still leave your ultimate goal the same (dual-channel X15 quad-drive RAID 0), would be to purchase just one GD7031 internal TPO ribbon cable, and one set of external cables and terminators, and put both drives on the same bus using a UL3D. You will be using only half the card, and half the capacity of the enclosure, but your costs of entry will be limited to two drives, a quad-bay MAP5043 Burly, one G7031 Int TPO cable, one external .8mm Champ to 68-pin cable, one GD6299 terminator, and one ATTO UL3D. If you do not already own SoftRAID, that will run you another $145.

proceeding this way, you save on cables and terminators (you buy only half of what you ultimately need), and defray half your drives for future expansion.

one other point: it is possible, with the bG3, to install two drives internally, and run them both off an ATTO, a Miles2, or an Apple/Adaptec 2940U2B. This is the most economical way to begin, and there is nothing preventing you from migrating these two drives, cable and SCSI card to a Sawtooth later, or installing the drives in an enclosure in the future.

there are a couple of considerations here.

the cheapest way out, period, would be the Apple/Adaptec 2940U2B with FoxConn cables at $114.99, with a pair of X15's and a pair of drive sleds (one each 922-1124, and K8030).

this will be compatible with both OSX and a future Sawtooth. I would consider this card and cable disposable, however, as they are the slowest options, as well as the most affordable.

the optimal way out, is also more expensive. Using an ATTO UL3D inflicts a $500 price-tag at the outset. Then you need an internal cable with pigtail and terminator, like the GD1200 and GD6299. These run $181 together. Then you need your drives, and again, SoftRAID. This will deliver optimal performance affordably now, and migrate very nicely to a Sawtooth in the future.

hope this helps.

05-28-2001, 10:01 PM
Of course since you are looking to run a RAID (0 or 1) setup, the MilesU2W would be a better choice. You get the cabling, termination, card and SoftRAID for $200. The Adaptec would run $115+$145=$260

I'm sure Mag will agree the MilesU2 is a better card overall. MacOS X drivers are coming out (in beta right now) so you could migrate it to a new box. With the Sawtooths you definately want to go with a U160 card, but you dont have to right away.

The only bad thing about the X15 Cheetahs, right now, is that they only come in 18GB sizes. Of course running several of the x15's over a RAID-0 setup can fix that http://macgurus.com/infopop/emoticons/icon_biggrin.gif

05-30-2001, 05:20 AM
Beige are chipset limited to 75 mb/sec. Therefore, an Atto card is a waste of money(I know, I have one sitting in a box.)
Magician has a 2940b with cable, for 114. You could buy two of these, run one drive on each card, and still be WAY ahead of the ATTO card.
Frankly, I bought the 2940B, replaced a 4 drive, x 15 array, with a two drive array, and don't really notice any difference. The 4 drive was on a beige 333, it's now a two drive, and it works fine.

What other cards do you have in your beige? Since it really has only one busmastering slot, and a chip set limit, the dual vs. single channel card argument doesn't carry much weight with me. Dual cards improve cache data transfer, and that makes them worth money. Single cards are limited by the pci bus, and that's 33mhz/32 bit, or, about 115mb/sec. However, the beige, limits this to 75mb/sec, so the only point is future compatibility with 64 bit/66mhz slots. Is that worth over 400 dollars????

06-09-2001, 08:22 PM
Hey, thanks for the replies.

I've been putting allot of thought to this - lemme lay them on the table...

As inexspensive as the MilesU2 is, I would like to stick with the UL3D because
a. I will be migrating to a sawtooth sometime soon
b. I only want to invest in (a) good board(s) once, I want this setup to last
c. I'm limited in PCI slots (USB and firewire take all but one slot right now.)
d. Besides, for scalability's sake, I'd like to be under Ultra3 LVD specs.
I am alittle worried about ATTO UL3D support for OS X though.

I would have loved to put the Cheetahs inside, but there simply isn't all that much room in my beigeG3 desktop. There's already two ATA drives in there, and even if I did throw one out to make room, im not quite comfortable cramming two 15K drives right on top of eachother and surrounded by hot plastic rather that steel.

My original setup I had in mind would have set me back quite a bit, but magican had a point (why didn't i think of that?) I can save a huge ammount if i concentrate on only one set of cables and duplex later, when I have a PCI bus that can take it.

I just have three more things to ponder - please help me if you know them off the top of your head:
a. How does the performance of one 15k Cheetah compare to two on one channel? ( Capacity may not be that much of an issue for me)
b. Does anyone have an idea about the ATTO UL3D and support for OS X?
c. Is there an inexspensive usb-firewire combo card out there? One that is OHCI, OS X compliant and all that good stuff?

Sorry it took me so long to follow up - I've been sorta busy

06-09-2001, 09:07 PM
the RATOC is, IMO, the best combo PCI FireWire/USB board available.

the ATTO UL3D is compatible w OSX now, as is the UL3S.

there is no real problem with dual X15's inside that machine.....the way the desktop is built, you'll have one IDE drive down low, beside the logic board....then one X15 next the the CD-ROM, and the other next to the floppy. If you like to hack, you can pull your floppy, and stick your other IDE drive there (assuming you have a rev b bG3).

finally, a single X15 is a joy to use. The hell of it is, though, that these drives almost scale perfectly as you add drives. Adding a second drive will ALMOST double your thruput. I would stop there in a bG3, though, as you aren't going to get sustained writes faster than 75MB/sec anyway off that logic board.

i guess what i am saying is, a single X15 is great. A pair is optimal in that machine.

just my two cents.

others may have different views.


[This message has been edited by magician (edited 09 June 2001).]

07-12-2001, 02:58 AM
As usual, you are right on the money. Dual X 15s work great in a mac beige.

You can also get a sled, mount one of the drives on the floor of the machine, and set it up in an Ultimate hardrive cooler.

Cool, and helps cool everything else down.

Been there, done that. Works fine. I still recommend the adaptec card. By the time you get around to buying a new machine, the scsi standard may well have changed, and faster, much cheaper cards maybe avaliable.

Why spend 5 times as much for an ATTO?

Up to you.

I would keep the beige. With a processor upgrade, they jump, and I like having onboard scsi, etc. for all the peripherals.

Great machine, good price. Nice backup.