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SCSI Question/Raid 0 Performance

Crusty

Crusty

Lifer
RAID 0 HDTach Results

Adaptec AAA-131U2 Raid Card

I have 2 Maxtor 18gb Atlas 10k III drives, same firmware, and everything. Both drives perform fine by themselves, but when I put them in RAID0 it maxes out at 40MB/s. My SCSI Bios is set so that it supports 80MB/s on a wide LVD channel. I am using an LVD terminator after my two drives...could the cable be causing the 40MB/s max transfer? I don't have any other cables to test with..none of them have enough connectors on it, only 3(card+drive+term.).

Is there something else I could be doing wrong?

Thanks
 
I you check the Cosbi thread, you will see my pathetic score with 5 10k 18.4 gig Cheetah (U160) in raid0. I think you did better. I tried different stripe sizes and it didn;t change. I would just leave it at 64k (thats what I am using). Cosbi doesn;t seem to like raid controllers or something. And I know my array is fast, I installed XP in 4 minutes!
 
Originally posted by: Markfw900
I you check the Cosbi thread, you will see my pathetic score with 5 10k 18.4 gig Cheetah (U160) in raid0. I think you did better. I tried different stripe sizes and it didn;t change. I would just leave it at 64k (thats what I am using). Cosbi doesn;t seem to like raid controllers or something. And I know my array is fast, I installed XP in 4 minutes!
Click to expand...

Well, it didn't go much faster then the install did to a Single U160 drive..I know my performance isn't quite right...
 
Is your cable LVD-compliant, and what are the drives' SCSI IDs? Is the SCSI card indicating full 80MB/s when it goes through its drives at startup, or within its BIOS?
 
Hopefully, Shuttleteam pops in soon. He can fix anything. 😎

Possibly your cables are bad. Have any others you can use?

Also, do your cables have multiple connectors? I.E. can you terminate "a few connectors up" and try that?

I agree w/Mark; COSBI sucks ass. My gaming rig has a two-drive stripe. Two 18GB 15K RPM drives. My COSBI score is lower than a single 5400rpm IDE drive. :roll: I don't think so.

In Drivebench, I get 110MB/s reads. COSBI can kiss my SCSI Butt. Heh, "SCSI butt" funny. 😀
 
Yeah, my cable is a 6 device cable, with 4 drives on it and an LVD terminator immediately after the last drive...

two of my drives are SCA-80 pin drives so I have the adapter on them and those have on board active termination..could that be messing with my to 68-pin drives?
 
Originally posted by: MCrusty
Yeah, my cable is a 6 device cable, with 4 drives on it and an LVD terminator immediately after the last drive...

two of my drives are SCA-80 pin drives so I have the adapter on them and those have on board active termination..could that be messing with my to 68-pin drives?
Click to expand...

Those adapters are the likely culprits. If any device on the chain falls back to SE mode, then the entire chain drops into SE mode. Remove those 2 drives and see if that fixes the problem. Also keep in mind that Adaptec RAID cards stink. So, though your performance should be better, don't expect much more if any improvement over a single drive.
 
Originally posted by: Pariah
Originally posted by: MCrusty
Yeah, my cable is a 6 device cable, with 4 drives on it and an LVD terminator immediately after the last drive...

two of my drives are SCA-80 pin drives so I have the adapter on them and those have on board active termination..could that be messing with my to 68-pin drives?
Click to expand...

Those adapters are the likely culprits. If any device on the chain falls back to SE mode, then the entire chain drops into SE mode. Remove those 2 drives and see if that fixes the problem. Also keep in mind that Adaptec RAID cards stink. So, though your performance should be better, don't expect much more if any improvement over a single drive.
Click to expand...

Yeah, i've tried it without those drives on the chain as well. The card, upon boot shows all the drives running in ULTRA2-LVD mode..which is 80MB/s...
 
Adaptec RAID0 might as well be called JBOD. Performance is similar.

Do NOT expect stellar results with this HBA! It has a very slow processor. Do you have the default 2MB cache?

Also, HD Tach does not report sequential transfer rates correctly on most RAID arrays, especially intelligent adapters.

The only way to gauge performance with any kind of faithful results is to use IO Meter which can be complicated to set up and use.

You can also try ATTO and see if the results.

SCA to 68 pin adapters are generally a no-no. If the HBA reports full speed on startup you are usually ok. I would still check to see if media errors are being reported with anything in the signal path!

Cheers!
 
Originally posted by: shuttleteam
Do you have the default 2MB cache?
Click to expand...
No, I have a 64mb Chip of Crucial ECC in there.

Also, HD Tach does not report sequential transfer rates correctly on most RAID arrays, especially intelligent adapters.

The only way to gauge performance with any kind of faithful results is to use IO Meter which can be complicated to set up and use.

You can also try ATTO and see if the results.

SCA to 68 pin adapters are generally a no-no. If the HBA reports full speed on startup you are usually ok. I would still check to see if media errors are being reported with anything in the signal path!

Cheers!
Click to expand...

How would I check for media errors, or more like what do you mean? 😉
 
Media errors can be monitored and reported via software monitoring where supported. Usually this is a utility that is installed on the host computer.

The BIOS can also report these as well as long as the hardware supports this feature.

Media errors are frequently caused by faulty cables, improper termination, impedance mismatch or standing waves along the SCSI bus. A failing drive can also cause this, but this (fortunately) is not as common.

Cheers!
 
Originally posted by: shuttleteam
Media errors can be monitored and reported via software monitoring where supported. Usually this is a utility that is installed on the host computer.

The BIOS can also report these as well as long as the hardware supports this feature.

Media errors are frequently caused by faulty cables, improper termination, impedance mismatch or standing waves along the SCSI bus. A failing drive can also cause this, but this (fortunately) is not as common.

Cheers!
Click to expand...



Okay, the adaptec C/IO management software reports no errors on my drives. I do have Dual onboard U160 on my mobo, so I am gonna try and put my other drives on that and see if my performance increases.

Do you recommened any cheap SCSI RAID controllers, doesn't need to do more then 80MB/s..but a 160MB/s card would be nice. Unfortunately I only have 32-bit/33mhz PCI slots...
 
Unfortunately I only have 32-bit/33mhz PCI slots...
Click to expand...

That is a limitation that will kill performance with large arrays.

The Elite 1600 series has decent 32/33 performance and is available for a reasonable sum of money.

Cheers!
 
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