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HELP: Quad SCSI RAID 0 is SLOW

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Old 01-04-05, 03:03 PM Thread Starter   #1
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Unhappy HELP: Quad SCSI RAID 0 is SLOW


Hi, my configuration is as follows:
-------------------------------
Host adapter:
Adaptec 2100S SCSI RAID LVD 160

Hard drives:
Twin Seagate Cheetah 18gb 15,000rpm ST318452LW
Twin Seagate Cheetah 18gb 15,000rpm ST318453LW
(All four drives in RAID 0)

SCSI Cable:
4 device Adaptec U320 w/ terminator
-------------------------------

'HD Tach' and 'SiSoftware Sandra Pro' both said that my dual ST318452LW RAID 0 array was crunching about 55 megs a second. My problem is that after upgrading to the QUAD array as stated above that number did not change one bit. Im still only seeing around 55mb of throughput. I have the latest BIOS and firmware updates, what am I missing here? I feel like I should be atleast seeing 100 mb avg...
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Old 01-04-05, 03:14 PM   #2
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You sure its set to raid 0 and not raid 1? btw with 4 15k scsi drives you should be pushing 200mbps easy.
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Old 01-04-05, 03:21 PM Thread Starter   #3
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100% sure. The bus is only 160 on the Adaptec 2100S and supposedly it IS hardware RAID and not just driver RAID.
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Old 01-04-05, 07:00 PM   #4
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What are the other specs of your system?

You might actually just burst and top out at 120mbs. Because of the PCI bottleneck.

55mbs is a tad low. You should be getting about 60-70mbs of throughput, but SCSI drives aren't optimized to be in a RAID array they are optimized for Server operations. That might be your problem, I'll wait for a SCSI guru to come by and fill you in. But most of the time SCSI drives aren't optimized for RAID 0.

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Old 01-04-05, 08:07 PM Thread Starter   #5
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Thanks for the input guys, my system specs are this:

Asus P4P800 Bios 1008
Intel P4 2.8
2x OCZ 512 Dual Chan EL rev2
BFGTech 6800 UOC
Intel e1000 Pro Nic (the damn integrated 3com gigabit is shot)
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Old 01-04-05, 10:39 PM   #6
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Welcome to the forums!

You have a several factors working against that array's performance. First, the PCI bus is a tremendous bottleneck, max bandwidth is usually tops out at around 110-115MB/s. Next, the controller itself may be a contributing factor. Adaptecs are usually reliable, but not known for speed. This controller has had several similar comments at 2CPU. The cache memory on the card is 32MB on most cards, but upgradeable to 128MB. This may help somewhat. The onboard processors are notoriously slow on U160 RAID controllers and may be contributing as well. Having the four drives on a single cable could lead to contention, but the system is being limited prior to that point.

55MB/s is very slow for that array in spite of everything. A single 15K3, ST318453LW, should push more data than that. I have a 147GB MAP 10K that sends more than you array.

In terms of performance, first we need to verify the results. HDTach often has problems with RAID arrays. Sandra's accuracy is notoriously bad as well. Get a quick sniff with ATTO's benchmark utility from the SCSI tools. You will have to register, as they now require it for download.

http://attotech.com/

Once downloaded and installed, run the benchmark utility with a length of 32MB and a queue depth of 10. This will give a better set of quick data for assesment.

As far as improvement in rates, the cheapest would probably be to get a LSIU160 entry level nonRAID controller for about 35.00 from newegg. Run a 15K.3 as boot and a second on the same channel for programs. Due to burst transmission and command queueing, you will get about twice the throughput of the current array. I'd probably save the other two drives for another rig or use them as a test bed/scratch disk in RAID-0.

Increasing the cache RAM on the controller may help, but it will likely be unbuffered ECC PC100 SDRAM, expensive and sometimes troublesome to find. Changing stripe size and clusters may help also.

Good luck and post back on any results or thoughts. I and others here have been around a couple blocks.
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Old 01-05-05, 01:33 AM Thread Starter   #7
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Thanks Xaotic, here is an image of the result. I seemed to have fared better than I thought.



Would it be possible for you to recommend a good Hardware RAID U320 SCSI PCI-X true 64bit card that cost less than $400?

I've been looking at the Mylex AcceleRAID 500 and the LSI LOGIC 21320-R. Is either Mylex or LSI a decent brand?

Also, what are your thoughts on the Supermicro? I've never used them before but I'm seeing a P4SCT in my very near future.
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Old 01-05-05, 09:42 AM   #8
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Reads are still low, but writes are as expected due to the speed of the onboard processor. I've heard tales of people with writes in the 20MB/s range due to parity calculations on RAID-5 arrays on these cards.

Costs have jumped lately. The bargain(more driver RAID than true HW RAID) card that had been affordable has gone up in price. The LSI 21320-R Kit was about 140 at newegg, but it now 216.00 plus shipping. The cards that I could strongly recommend are the LSI 320-2X, but they are around 800.00. The 320-2 just doesn't have the sheer performance and is still in excess of 600.00. Given the purchase constraints and if you are only planning on RAID 0 or 1, I'd probably give the 21320-R a shot. I've wanted to try one, but never got around to it, too many other projects going on.

From an overclocking standpoint, Supermicro boards simply do not fare well. BIOS is pretty much stripped of options. They do make very nice stable boards though. I've used several in servers. The board itself seems a collection of compromises(most do). The 875P chipset does not support true PCI-X and is a 64/66 single bus. You will lose one to the AGP for cooling a decent video card as well. As a contrast, my workstation board is an MSI dual Xeon e7505. I do lose my only 32/33 PCI to the AGP, but have 3 PCI-X busses, dual interface 64/100, dual interface 64/100 and single interface 64/133, dual onboard U320 is a plus as well. It doesn't overclock in a conventional sense, but limited mods can be made. For an IO box, it's great, but costs are high. Look around before you buy the SM. Xeons are another good alternative. Post what you are looking to do with the system as well, there may be other options.
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Old 01-05-05, 08:16 PM Thread Starter   #9
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In real numbers what is the limit of a 66mhz PCI-X vs a 100/133?

Also, is it true that the Intel SRCU42x and the LSI Logic MegaRAID SCSI 320-2X are physically identical? Because the Intel SRCU42x is significantly cheaper.

As far as this systems purpose, it's just for my programming/administration/gaming/torrents and the like. No real need for that kind of power but It's what I want to spend my money on. And I've come this far... I do have a pretty fast local gigabit lan server I'd like to have screaming fast SMB file sharing with.
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Old 01-06-05, 06:03 AM   #10
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64/66 is 528MB/s, while 100 is 800MB/s and 133 is 1028MB/s. Overhead will reduce the theoretical numbers somewhat. As a practical matter, even large arrays on very fast controllers have trouble getting over 400MB/s.

Yes, they are identical, but do have some firmware differences. Either will work very well.

Given that usage, the board would suit the needs well, as long as you are not planning on overclocking. Normally, that's pretty much a given around here.

On costs, I probably have most people beat, so I completely understand the situation.
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Old 01-06-05, 09:16 AM   #11
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If you've got the time you could also wait and see how PCI-E RAID controllers pan out.

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Old 01-08-05, 01:30 AM Thread Starter   #12
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Ok I've managed to come up with these final candidates.

Supermicro P4SCT
Pros:
-800mhz FSB
-Dual Channel DDR
(Better for gaming?)
Cons:
PCI-X 66mhz
(875P not true 64bit?)


MSI E7505 Master-LS2
Pros:
PCI-X 133mhz (Oh yeah!)
Dual Xeon capacity
Cons:
533mhz bus
DDR 266 (Oh nos!)

This is my dilemma:

Do I risk limiting my hard disk array's performance by going with the 64bit PCI-X @ 66mhz, Which leads me to my question: Will the Intel SRCU42X with quad RAID 0 Cheetahs need more than 266 mb/s?

or...

Do I risk my precious Doom 3 frame rate with the server oriented Xeon CPU with its slower memory speeds.
Which brings up yet another question: Will Dual Xeons rock my Doom 3 world?

As far as the CPU goes the bottom line is my frame rate.

Finally I have to ask about AMD Opterons. I found this board. This board takes full advantage of the memory I've already bought and it has everything I want. My question is, are Opterons worth a crap? (Specifically the 242 and 244)

In short, in your opinion, which Chipset/CPU will give me the best frame rate. I really find myself swinging toward the Iwill.

Thanks for any input. It is appreciated.
-Borderline
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Old 01-08-05, 02:39 AM   #13
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Power strip may actually be able to help you with getting a higher throughput. Normally you would think power strip is only good for vid card overclocking but it can also be used to tweak PCI latencies. I found that using a higher latency for your SCSI card can greatly speed up your transfer rates. The default latency is 32 but somewhere around 128 or 160 was the sweet spot for my SCSI raid setup. Your system may respond differently but itís worth a shot before sinking more money into the situation. Itís not going to do miracles but itís sure worth a try.

I never was able to get insanely fast write speeds but reads maxed out close to 180 MB/sec after tweaking. This was using 4x 10k RPM 18.2 Seagate drives. They arent exactly cutting edge technology with 1 MB cache and 80 MB/sec interface but they are cheap. The scsi card was (thanks to Xaotic) a 64 bit PCI IBM ServeRaid 4H with 128 MB cache and 32 MB mem for the 266 MHz IBM PowerPC 750 processor with 1 MB L2. The card was very nice however newer cards can be a bit faster.

I had as many as 8 of those 10k Seagates in Raid 0 but performace wasnt any better than 4 due to other system limatations. After my raid array grew to cumbersome I decided to go to a single 15K rpm drive and be done with it.

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Old 01-08-05, 08:14 AM   #14
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Opterons are not crap. I think you're diving in to SCSI/RAID and Duals for the wrong reasons.

Games are better run off bleeding edge hardware. Say a FX-55, Raptor and an X800XT-PE.

If you're gonna spend money on SCSI/RAID and dual, you're down to doing business, encoding and so on. Not to say that you can't play D3 on dual server opteron system, but if you want nothing but super fast gaming fun you gotta be building a super fast gaming system.

Duals and SCSI/RAID have better longevity and staying power than any desktop system tho... The Opteron will be continued for at least another 1-2 years same with the SCSI components.

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Old 01-08-05, 10:43 AM Thread Starter   #15
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I know bleeding edge components are a better choice for gaming. (I just sold my MSI K8N Neo2 and Athlon 3500 because the mobo wouldn't work with my old adaptec SCSI card when my BFGtech is in the system, some kind of IRQ conflict that MSI didn't want to talk to me about) and the SCSI RAID is not for games.

I really don't want to have to use Xeon or Opteron much less pay for a dual CPU mobo. I'm not under the impression that they will give me better game performance. It would be nice if they did, but I fear that they will only hinder performance.

It's this simple, I need a PCI-X motherboard with an 8X AGP slot. I already have the SCSI equipment. I am now forced to choose between the above. All the above, according to their specs, will work for me so theres only one concern left in this choice: Doom 3 frame rate. Which has the best? I am willing to go dual CPU's if it will significantly help the frame rate. Otherwise those dual CPU motherboards will only get one CPU.
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Old 01-08-05, 12:32 PM   #16
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The Opterons will be better at gaming. The on Die memory controller reduces latency and they are just really powerful chips, the stronger FPUs also help in games.

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