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schalliol
12-08-2000, 11:50 AM
With a miles2, how many drives would be optimal in RAID 0 with SoftRAID? I think I've heard SoftRAID say that beyond a certain number it's not useful to add more drives. With the 4MB Cache 'cuddas would 3 (or 4) be faster than 2? What would the speed difference be? Considering that cost is an issue, if 3 or 4 is faster than two, it would be better to add those than buy a new card and have two.

Also, in practice, how many drives are people able to fit into new G4's? (easily and with difficulty).

Thanks,
Jon4

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kaye
12-08-2000, 12:24 PM
s,

Your 9600/200 vintage Mac with a single Miles2, I found with an S900 and a PTP both G3 accelerated that once sustained writes reached 40MB/s, that was it, no faster. I could do that with two 10k Cheetahs on a single Miles2. Three 10k Cheetahs would provide faster sustained reads but sustained writes were stuck at 40MB/s. A single X15 on a Miles2 would also give sustained reads/writes at 40MB/s. More X15's would increase sustained reads, but sustained writes still 40MB/s. The trick to increasing sustained writes is two Miles2.

My tests with my PTP:

Test 5 - one X15 and one Miles2
Test 6 - two X15 and one Miles2, striped
Test 7 - two X15 and two Miles2, striped

ATTO EPT 8MB, 2 Cache Segments, no Disk Cache, in MB/s:
Test 5 - SR 40.33, SW 40.20
Test 6 - SR 70.12, SW 40.39
Test 7 - SR 77.73, SW 75.50, PR 133.02, PW 76.00

SpeedTools QuickBench:
Test 7 configuration:
Xfer Size---Sequential Read---Sequential Write---Random Read---Random Write
1 MByte------75.919 MB/sec-----70.915 MB/sec----53.467 MB/sec--60.527 MB/sec

Test 8 - four X15 and two Miles2, striped, two X15 per Miles2
(SoftRAID driver set for 768 Maximum Concurrent IOs and 1369 Memory Pool Size, then X15's set for 23 Cache Segments via FWB Configure 3.0.2, in that order)

ATTO EPT 8MB, 2 Cache Segments, no Disk Cache, in MB/s:
Test 8 - SR128.60, SW 75.78, PR 137.13, PW 76.27

SpeedTools QuickBench:
Test 8 configuration:
Xfer Size---Sequential Read---Sequential Write---Random Read---Random Write
1 MByte-----128.808 MB/sec-----71.736 MB/sec----81.791 MB/sec--68.745 MB/sec

MacBench 5:
(Note, these X15's are brand new and, IME, they get faster as they break in)
Test 7 - Disk 4212, Pub Disk 3440 (only ran this test once)
Test 8 - Disk 4503, Pub Disk 3622 (1st test)
Test 8 - Disk 4536, Pub Disk 3659 (2nd test)
Test 8 - Disk 4546, Pub Disk 3666 (3rd test)

IMO, two Miles2 and two X15 is the practical limit. The extra $1000 for two more X15's only increases sustained reads. Sustained writes still remain at about 76MB/s. I realize that you are talking Cudas. But the same limits would apply. I just don't know how many Cudas it would take. But even a single X15 is the equivalent of between two to three (closer to three) 10k Cheetahs striped. k

[This message has been edited by kaye (edited 08 December 2000).]

Dogstarman
12-08-2000, 01:20 PM
The Gurus themselves have done a bit of testing with up to 8 Cheetahs on one Miles...the older 10K Cheetahs...getting in the neighborhood of 69MB/sec sust reads and 79MB/sec sust writes on their PM 7500 with a G3 400. Check out their page on Seagate drives, and scroll down to the section "About Thruput". It gives their experiences briefly.
http://www.macgurus.com/shoppingcart/showrampage.cgi?mg_hdseagates.html

PENDRAGON18
12-08-2000, 06:23 PM
You can easily install 4 drives in the YOSE/SAW cases. The last bay is double stacked - so be careful about the HEAT http://www.macgurus.com/ubb/eek.gif Also you could put one drive above the CD/DVD but again this will generate more heat and draw more power.

The 36GB 10K Cheetahs are actually a slightly better deal than the 18GB 7.2K Cudas when you compair GB to $$. So it really depends on how much speed you want and how much size you want. For some reason the Cudas are only 18GB, so

4x18=72GB of Cuda Storage! http://macgurus.com/infopop/emoticons/icon_smile.gif
4x36=144GB of 10K Cheetah Storage!!! http://macgurus.com/infopop/emoticons/icon_biggrin.gif http://www.macgurus.com/ubb/kickass.gif

I'm not sure how hot this would run. I hear the new Seagates are fairly cool running. You could have several stripped volumes for different uses: video, mp3, games, scratch disks, boot volumes, etc... and do not forget back it up!

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Have fun storming the castle!

schalliol
12-08-2000, 06:56 PM
Does anyone have a picture of a G4 with 4 or more drives in it online (with the case open of course)?

Also, my 9600 is very cool, even with five hard drives, the CD-R and CD-ROM. The impression I keep getting is that the G4's case doesn't cool as well. My 9600 has that enormous fan and vent on the other side, so I assume that helps a ton.

I would like to have a striped volume that is damn fast, and a mirrored volume for redundancy. (see other post on cheap external cases in the SCSI section).

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AOL IM: JSchalliol
Computer Equipment: http://www.schalliol.com/computer.html
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[This message has been edited by schalliol (edited 08 December 2000).]

Dogstarman
12-08-2000, 07:49 PM
I was looking for just such a pic. None found yet. In my limited experience, the new cases are not the greatest for cooling, but they are better than the B&W machines. Keep in mind that all the new drives are WAY cooler than a generation or 2 ago. I actually used an X15 G4 the other day and the drive actually wasn't that warm after a couple hours of messing around.

magician
12-09-2000, 06:10 AM
right. You will find that X15's, though they are the fastest drives on the planet, are actually very cool mechanisms, and I mean that literally, in terms of temperature.

if you look at the casing, it's almost a light form of cast iron. This is deliberate. It not only has superb heat characteristics, but also increases the weight of the drive casing itself, reducing vibration transferred to the platters, and to other mechanisms.

anyway, it is completely viable to install a pair of X15's in the Sawtooth, with a pair of 75GB or 60GB IBM IDE drives stacked in the rear bay.

I would stripe the X15's. Since SoftRAID does not support IDE drives, you should use the two IDE drives as single fixed volumes. I would format those devices with either HDST3.11 or the version of Drive Setup included with the Sawtooth.

PENDRAGON18
12-10-2000, 09:07 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>the new cases are not the greatest for cooling, but they are better than the B&W machines.<HR></BLOCKQUOTE>

As far as I know the Sawtooth case and the B&W (Yosemite) case are EXACTLY the same - except the color. So I'm not sure how a Sawtooth system would cool better than a Yosemite - unless they added bigger fans or something. I'm sure the 9600 case cools much better. It is one of Apple's biggest and best cases.

If the X15s are cooler than the 'old' 10K cheetahs - get those - even though they are only 18GB and are probably a bit faster than the MilesU2W card can handle. RAID-0s are COOL, but you can not boot off them. Of course those fast IBM IDE/ATA drives are bootable. You can boot off single drive SoftRAID (not-really a raid) drive or even a mirrored (RAID-1) array, but that is it. I think you could hack around this with the 'PRAM' or NVRAM - but nobody has done it yet to my knowledge.

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Have fun storming the castle!

schalliol
12-10-2000, 11:09 AM
Two things:

1. You can boot off of a RAID 0.
2. It is true that the SoftRAID driver on a single drive is not a RAID, but also that RAID 0 (striping) is not a RAID either. It's just simply a disc array. Afterall, it doesn't satisfy the R in Redundant Array of Independant (or Inexpensive) discs.e

Dogstarman
12-10-2000, 10:17 PM
PENDRAGON,
Perhaps it was just the particular machine I dealt with (the B&W) but the X15 in that machine felt noticably warmer when installed in the same location. Maybe they had upped the cooling fan (the owner)....I dunno. I know the cases are physically almost identical..but I wasn't sure if any vents/etc were changed. There goes my limited knowledga again. I weas just speaking for the instances I knew. It is good to know better now. And I as well have been booting off of a RAID-0 for over a year, and have setup nearly a dozen machines to do just that. Damn those fools for calling RAID-0 RAID....Maybe SAID is more like is. Simple Array of Inexpensive Disks.

schalliol
12-10-2000, 11:30 PM
I was just being silly. Yeah, sounds good, thanks everyone for the answers, but I'm still not sure how many 'cuddas on a miles2 make sense. That was my original question.

Thanks again,
Jon

Dogstarman
12-11-2000, 03:37 PM
Jon,
As far as making sense? Well, that's a tough one. Ask yourself how many you need. Then multiply that by 3. That is how many you should get. That has been my rule for everything computer-related...processor speed...CDR speed...RAM...HD space...Huh. Maybe that's why I have 2 jobs.

But seriously. As far as keeping cool, get the Miles hooked up to an external box and keep dropping drives into the array until the $$ runs out. Then borrow the $$ to buy more. Find a line where performance levels off and make that your Waterloo...looks like 2 X15's per card give you the best. You can always add in more drives, and an external case ALWAYS cools better than any internal setup I have seen. 'Cept maybe mine. That being the issue? I would go external in a G4. Save the internals for the DVD and CD burner. Keep the mothership nice and cool.

[This message has been edited by Dogstarman (edited 11 December 2000).]

Louie
12-11-2000, 08:18 PM
You don't "keep adding drives till the dollars run out" when using X15's. They are so fast that it doesn't take many to reach bus saturation.

Dogstarman
12-11-2000, 10:23 PM
Well, unfortunately, some people are not interested merely in saturating a bus. They will keep adding the drives until dollars run out. People that are looking to spend every cent they have (within reason) to build an over-done machine so that their business will not be let down or held back by lack of drive space or performance.

My suggestion was half-kidding, with the notion in mind that most of us do indeed over-do our machines a little. I like to think of it as planning for the future. I could care less about bus saturation. I care more about meeting my performance needs and space requirements. And that NEVER decreases.

I am adding drives when the need arises. If the need never arose, I would still be booting off a floppy and running my apps off another (Aaah, my Mac SE). But as luck would have it, I have migrated from one 9GB Cheetah to 4, and plan on making that 4 18GB X15's within 90 days or so. Not to max out my bandwidth, but because Cheetahs are THE best, and my line of work depends on having the best (or darn close). And space requirements have tripled in the past 18 months (for me). So as far as I am concerned, I will keep adding drives until the dollars run out or until the need no longer exists.

So that in mind, my last post holds true for some things...2 drives per Miles seems to yield the most reasonable thruput. Beyond that, the levels seem not to jump as high. So stick with that and buy what you need, plus the "usual" 15% headroom for imminent expansion. That is my professional opinion in all seriousness. I will try to mix less humor into the thick of things. Hope we have helped you a little in this mayhem, Jon.

Louie
12-11-2000, 10:33 PM
Fine; I just don't want people to think that the performance of a RAID 0 volume made from X15's will just get faster and faster if you keep adding drives.

Dogstarman
12-11-2000, 11:06 PM
No offense here, Louie. And none there either. That was my point in finding a place where things level off and make that your place to call home. That's why I made sure to make that point. Performance will always increase with more drives, just after (I would say) 3 drives on a bus, it is so marginal, it becomes plain unnoticeable. Like overclocking 3 more Mhz to get a little more speed. The only reason I even made a comment about adding more drives is to add space.

I won't even try to get into a battle of words/wits with anyone here, for it is surely futile. My 16 years on/off in the Mac world is nothing compared to a dyed-in-the-wool old-timer in computer hardware. This has seriously only become a severe passion of mine these past few years. So keep me in check. And I'll try not to let my passion/humor go unbridled.

Jon, have the posts helped you out? Cuz that's why we're here.....

[This message has been edited by Dogstarman (edited 11 December 2000).]

[This message has been edited by Dogstarman (edited 11 December 2000).]

schalliol
12-18-2000, 02:39 AM
The posts have been somewhat helpful, but most not right on topic. Your comment that adding more drives always increases performance is helpful, if true. However, I've read that (I think from SoftRAID) since the drivers are software, that at some point that the processing overhead of splitting the data across multiple drives slows down the potential of splitting it across all those drives. A hardware system (if built correctly) shouldn't have this problem (under a certain number of drives). I was trying to get what point this would be for 4MB 'cuddas on a miles2 (where did all this X15 talk come from?).

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AOL IM: JSchalliol
Computer Equipment: http://www.schalliol.com/computer.html
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magician
12-18-2000, 03:14 AM
I can't answer the core question, but I can state from experience that I have personally built arrays using X15's beginning with two drives and increasing in increments of pairs up to eight drives. In fact, the benchmarks are on our FTP site, and you should feel free to download and consider them. You will find that performance continues to scale, increasing with each pair of drives added.

a statistician will need to analyze the raw benchmark data to determine whether and how much the performance gain decreases as drives are added. Percentage-wise, you do get a greater proportional performance gain adding one drive and striping a second drive over a single drive than you do over adding matched sequential pairs, but the gains are dramatic in the beginning, almost doubling thruput with each increment.

my point is, like heroin (I am told), you need more as you go to get less. Interestingly, though, the sustained benchmarks we documented continued to scale upward as drives were added. The increase just wasn't, proportionally, as great each time with each new pair, if that makes sense. We haven't tested more than eight X15's, as frankly we've never had that many unallocated at one time since we ran our original benchmarks.

You do get better performance from eight drives than from six, however, and more from six than from four, and more from four than from two. The gains are more dramatic at the lower end, though the high end did yield 180MB/sec sustained reads and 140MB/sec sustained writes across dual channels in a Sawtooth 500MHz with an ATTO UL3D.

The sort of results you will see will be, in my experience, unique depending on the machine, and depending on other factors like firmware revision on the SCSI host and how you set up cache segments and other mode page parameters on the drives. Obviously, you will get better performance if you use a 64-bit PCI subsystem and bus duplex across dual-channels than if you are using a 32-bit PCI subsystem.

Other threads have confirmed that in 32-bit subsystems, the Miles2 (which still outperforms all other cards in vintage Power Macs) maxes out at 40MB/sec sustained writes regardless of how many drives you attach. If you use dual cards in dual PCI buses, you can get 75MB/sec sustained writes. Sustained reads of 100MB/sec are readily obtained, and I believe K has coaxed up to 120MB/sec or so from his X15's in his PowerTower Pro.

I can't help you where Cudas are concerned. They are too slow, IMO, and I don't build Cuda RAID very often. I think the price/performance delta clearly favors X15's. You can get more performance from fewer drives, spending less for more performance overall.

As for hardware RAID, we've tested a number of them, and we've never seen performance beyond 50MB/sec from any of them. I make no claim of comprehensiveness. I will say that the unit we're currently struggling with in the basement has firmware defects that prevent it from using more than two drives at a time in a RAID 0, and we're still trying to figure out how many drives it actually uses in RAID 5. We have yet to actually get it up and running to a point where we can benchmark it. Figuring out whether we have defective drives, defective caddies, or defective backplane connectors is kicking our asses, and we just don't have time to puzzle it out, part by part.

It is making us very nostalgic for our simpler software RAID. They are much easier to troubleshoot, cost less, and perform better. Granted, we don't have RAID 5 yet in software. And our enclosures are still ugly, and beige. We're containing our disappointment.

http://macgurus.com/infopop/emoticons/icon_biggrin.gif

kaye
12-18-2000, 10:55 AM
Jon4,

Pretty hard to follow after magician's post, but here goes.

The throughput I and others posted is not meant to talk you into X15's or 10k Cheetahs. It was meant to give you an idea of what the ballpark throughput limits are in a vintage Mac with Miles2, SoftRAID, and a striped array. Your Miles2 with 2x 4MB cache Cudas, what sort of sustained reads and sustained writes are you getting now? Given your existing throughput, a guesstimate can be made as to the gains with more 4MB Cudas. Apparently, no one has cruised through here with a Miles2 and Cuda striped array to comment more on topic.

Tell us what you are getting for sustained reads and sustained writes, and I will try to guess based on my Miles2/X15s and Miles2/10k Cheetahs data. Using one Miles2 in a vintage Mac, there is a point where sustained write peaks and cannot be increased. Adding more drives causes sustained reads to increase up to another point, then the architecure of the vintage Mac and the overhead of more drives limits/stops any further increases by adding more drives. k

schalliol
12-18-2000, 12:09 PM
First of all, everyone, thanks so much for your thoughts.

Basically the way I understand it from all the posts is that adding more drives is better as a general rule. I do understand that X15's are also best (though the new Atlas 10k II's seem to DESTROY 10k cheetahs . . . I know your thoughts on them, so let's not get started).

One question though. There's mention of installing drives in pairs. Unless this is over multiple channels, I don't understand why this would be done.

Everyone, thanks again. Hopefully SoftRAID will get out a RAID 5 sw for X.

- Jon

MacMikester
12-18-2000, 06:27 PM
Hey Schalliol,

The idea of drives in pairs is only in keeping with the RAID principle of balance and symmetry in the dual channel or dual dual channel systems that are referenced. You can certainly add drives singly to a single channel card. Or a dual channel card, but then you introduce timing lags between accesses to the unbalanced channels.

Regards

schalliol
12-18-2000, 09:56 PM
Gotcha, Keeping channels even. That makes sense. Just wanted to make sure you weren't referring to singles too.

Thanks,
Jon?Ǭ