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LSI LSIU320 (SCSI) on PCI 33 MHz

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December 21, 2006 1:29:22 AM

Hey all,

Pretty basic questions about using an Ultra 320 SCSI hard drive (Atlas 15K II 36.7GB) on my new Gigabyte GA-965P-DQ6, which has a bunch of PCI Express slots and 2 - 33 MHz PCI slots. On my old machine, I had a bunch of 64 MHz PCI slots. I know 33 MHz should support well over 100 MB/s and these drives get a sustained transfer rate of around 85 MB/s, but:

1. Will I see any performance drop by putting the LSI card in a slower, 33 MHz slot?
2. Would I reap any advantage by buying an expensive PCI Express SCSI card and running the LSI from there?
3. Would any BIOS setting improve PCI latency/transfer rate to the SCSI card, or would that be a waste of time?

Thanks for your answers, experts! :) 
December 21, 2006 12:49:47 PM

Quote:
Hey all,

Pretty basic questions about using an Ultra 320 SCSI hard drive (Atlas 15K II 36.7GB) on my new Gigabyte GA-965P-DQ6, which has a bunch of PCI Express slots and 2 - 33 MHz PCI slots. On my old machine, I had a bunch of 64 MHz PCI slots. I know 33 MHz should support well over 100 MB/s and these drives get a sustained transfer rate of around 85 MB/s, but:

1. Will I see any performance drop by putting the LSI card in a slower, 33 MHz slot?
2. Would I reap any advantage by buying an expensive PCI Express SCSI card and running the LSI from there?
3. Would any BIOS setting improve PCI latency/transfer rate to the SCSI card, or would that be a waste of time?

Thanks for your answers, experts! :) 


1. Yes you will, the drive will be limited and you'll most likely be below 80mbs
2. Sounds like more of a rhetorical question. I've set up my system to have the LSI 320-2e with 512mb write back cache. My benches doubled with this set up.
http://forums.vr-zone.com/showthread.php?t=86367
3. You can't do anything as far as you bus being limited, try to get the LSI, if not use the perc 4e/dc. (youll need to do some creative editing in the txt setup files if you plan to use XP) Good luck!
December 21, 2006 1:30:43 PM

I want a one-channel SCSI card...am I going to be spending $400 to get a marginal speed boost?
Related resources
December 21, 2006 1:43:11 PM

Quote:
I want a one-channel SCSI card...am I going to be spending $400 to get a marginal speed boost?


I don't know how you consider the performance gap between PCI vs PCIe or even PCIx marginal. I don't think you realize that your drive on a PCI 2.0 bus will essentially bring your the overall performance down to the UDMA 6 with a marginal run off (with higher bursts of course). I realize that it depends on the speed of the PCIe and PCIx card, but even still at 4x or 100hmz bus, your gaining dual simplex bandwidth, not marginal at all.

You can find a single channel card at 1x and 4x speeds far under retail price. Just do some research.
December 21, 2006 1:50:37 PM

I will only be using SCSI for hard disks, though, which at Ultra320, have a maximum sustained transfer rate of 80 MB/s, though yes, they burst at around 170 MB/s. I'm inclined to think it's that sustained rate and average access time that define overall disk performance, rather than burst speed.

Am I very wrong here?
December 21, 2006 2:41:29 PM

No, your mostly right.

Those number you gave are based on your new PCI bus? Or the old?
I would say to just test it out on your new system, since you moving the the drive and controller to the new system you don't loose anything. But still keep in mind, the gain on the interface change is more than marginal, while still agreeably pricey. I'm running a raid 0 of 3 15k Cheetahs with a LSI 320-2e (dell perc) now. But before that I was using a 29320lp-r, which was fast on a PCI bus as is, but the migration for me (Gigabye 590 amd mobo) to the 8x PCIe interface is great.

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December 21, 2006 2:50:04 PM

Holy crap your combined seek/sustained transfer rates are impressive! I'm looking to configure my system as such:

LSI U320 -> 32 GB 15K RPM C: Drive for Windows and Program Files (maybe 16 GB used)
LSI U320 -> 16 GB 15k RPM D: Drive purely for swap file
SATA -> A large, 7200 RPM drive for storing MP3s

Obviously, no RAID is involved here. I don't do a lot of large file transfers; my usage scenario is a lot of small, quick data access. I'm a developer and do very little with large video/database files and therefore am not so concerned with massive throughput.

I appreciate your info, and I'll of course post my HD Tach numbers when I downgrade my PCI interface.

Before = 5.3 ms avg seek, 160 MB/s peak, and around 75 MB/s sustained.
After = ?
December 21, 2006 3:32:28 PM

Good Luck :) 
December 22, 2006 12:02:29 PM

Well, of course you were right. Here's my new data:

Random access = 5.5. ms
Sustained read = 83.3. MB/s
Burst speed = 87.4 MB/s <-- eww!

I'd like to buy a basic, non-RAID, PCI-e 1x SCSI card for under $250. Just a no-frills, LSI U320-comparable card.

Any ideas as to makes/models?
December 22, 2006 12:25:10 PM

I thought I came across one on the net some place, but I can't find it again. I know it was made by ATTO Technology though. They have a model EXPRESSPCI UL5D, but the D stands for duel channel. The retail price is around 340, and I know I've see them cycle on ebay for under 250, just not seeing it now. I'll let you know if I find the 1x single channel card again.
a c 179 G Storage
December 23, 2006 3:59:45 AM

Buy an adaptec 19160n or 29160 card on e-bay. It should be about $25. I have one in a 33 pci slot with a 15k fujitsu drive and get similar numbers to yours. The reality is, however, it is not noticeably faster than simply getting a 150g raptor. Check out storagereview.com for benchmark comparisons.
December 23, 2006 10:38:19 AM

Now why would I want to do that? I already have a great card (LSIU320) running at 32-bit, 33 MHz. And my numbers suck. I want to move to PCI-Express.
December 23, 2006 12:15:56 PM

Okay, I just bought the Dell PERC4E/DC with 128 MB Cache.

http://tinyurl.com/yc7g5r

Looks like a sweet, 2-channel, PCI-e 4x Ultra320 card that supports RAID. Hopefully, I'll be able to grow my storage out with it.
December 28, 2006 4:56:57 PM

Cool stuff man, I have the same card. Let me know if you have trouble getting the drivers to work. There are modified drivers for XP, but I heard that Vista and XP 64 have the driver needed.
December 29, 2006 10:00:54 PM

Got the card today. Thought I had hosed Vista, but realized I simply needed to get Windows to detect the PERC while it wasn't being used as my main controller. Once I booted, I put the drives in the new card, and my HD Tach numbers are much better:

After = 5.3 ms seek, 140 MB/s burst, 90 MB/s sustained at 2% utilization.

Now, I have a question. I could enable write caching on my drives with the LSIU320 card. I no longer have that option (in Windows). I looked at the Dell documentation, and it looks like I can set the write policy to Write Back thru the BIOS (this seems to be the same as the Windows option mentioned above). Link: http://support.dell.com/support/edocs/storage/RAID/PERC...

The problem is that while I've setup my non-RAIDed drives to each use this as the write method, when I later view the drive properties in Objects--Logical Drives--Info, I see the write method stuck at Write Thru.

Any ideas why this may be the case? I am noticing about a 20% slow down in my write speed from when I was using the LSIU320.
December 30, 2006 12:47:04 AM

You have single drives set as a raid 0? they should be able to have writeback enabled.
December 30, 2006 12:53:18 AM

Quote:
I could enable write caching on my drives with the LSIU320 card.


Unless you have a battery backup for the controller or an external batter for the system I highly suggest you do not use write caching. One power glitch while you are writing an important file and poof, instant corruption.
December 30, 2006 12:56:26 AM

PERC4e/DC has a battery, though if there is a problem with the battery then it will shut off...should check battery information in objects menu.
December 30, 2006 1:00:47 AM

Yeah--I have a battery backup on the card. Any ideas why the BIOS doesn't remember my settings? I just went to Dell's site and got the latest firmware (using the Windows installer; the pre-boot BIOS timestamp remains February 2005)
December 30, 2006 1:21:17 AM

Quote:
You have single drives set as a raid 0? they should be able to have writeback enabled.


Correct--in Vista, it's saying these drives are incapable of supporting write cache. Is there something special I need to do to allow this? I selected Write Back when I created the individual arrays
December 30, 2006 3:21:45 AM

Well, I figured out why I couldn't enable Write Back in BIOS: The battery had not yet full charged. Makes sense. Now it's enabled, however, I'm seeing disk performance not even up to snuff with my LSIU320 (Ultra 320 at 33 MHz)!

Should the attached image mean anything?

December 30, 2006 4:04:01 PM

Were you running vista on the other controller?
December 30, 2006 4:10:51 PM

Write-back cache is useful for server apps where the same piece of information is accessed repeatedly.

Write-back caching is not useful in personal machines due to the fact that you will be constantly opening up new files that are not in cache. This will in turn cause a cache miss and that will result in a performance decrease.
December 31, 2006 1:18:15 PM

Quote:
Were you running vista on the other controller?


No...it was XP SP2. Maybe Vista is doing something funky? Just seems weird that a U320 drive doesn't show a gain, but rather a loss, in performance from 33 MHz PCI to 4x PCI-e
December 31, 2006 3:19:12 PM

yeah, it doesn't make any sense, cause it has much higher bandwidth. what are you using to test the performance?
a c 179 G Storage
December 31, 2006 5:58:56 PM

Your controller is overkill for tne number of drives you have. The mechanical transfer rate of a 15k drive is somewhere in the vicinity of 80mb/sec, depending on the inner/outer location of the track. The controller on a pci33 interface is capable of 160mb, and on a pci66 or pci-e interface is 320, or the equivalent of four drives operating concurrently. If the pattern of usage is such that data is retrieved from the dtive's cache(2mb?), then it can be transferred in a burst at the speed of the bus. I would not expect this to happen often. Most single user environments will have only one, or at most two drive operations operating concurrently.
If you installed four drives in raid 0, only then would I expect to see any real improvement in sequential performance. This would be offset by a likely reduction in random performance.
If you have room in your case, you could pick up 4 18g 15k drives on e-bay for not very much and test it out.
!