Ikon

Hdd Speed Comparison Stuff

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Guest Eugene
My gut says the three drives in RAID.  But that's just a guess.

I'd bet the opposite. The older SCSI RAID0 setup has three things going against its when compared to a modern ATA drive for typical desktop performance- the fact that they're older, the fact that they're SCSI, and the fact that they're being run in a RAID0 array.

And yes, I'm being serious.

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People who don't know better don't realize that even early u160 drives often had str's in the low 20's as opposed to a new 8mb cache ide with almost the same access time but almost tripple the transfer rate. Tons of guys buy used 15k seagtes on ebay and can't realize why the performace is so low. (long sogh.... because they had like 4 to 6 generations of those drives and each one was 20 percent faster then teh previosus model. We have made huge gains in transfer rate in just the last 3 or 4 years. A scsi from more then 3 or 4 yaers ago ... even the fastest made have trouble keeping up with todays hot ides's "for the usage pattern of a normal desktop pc user"

scsi is no magic bean meaning its faster. Only the newer fast scsi drives out run the fastest ide's now. The gap has narrowed with scsi still leading seriously in access time but often a normal desktop user won't feel that as much doing what a normal desktop user does. It shows more in a multi-user server environement where the heads are moving around constantly. If your disk is defragged and you do stuff like a normal desktop user you do a lot of sequential reads and the firmware in the ide's are geared to this scenario.

Tex

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Guest Eugene
People who don't know better don't realize that even early  u160 drives often had str's in the low 20's as opposed to a new 8mb cache ide with almost the same access time but almost tripple the transfer rate...  even the fastest made have trouble keeping up with todays hot ides's "for the usage pattern of a normal desktop pc user" ... If your disk is defragged and you do stuff like a normal desktop user you do a lot of sequential reads and the firmware in the ide's are geared to this scenario.

I disagree. Empirical evidence has time and time again suggested that STR in modern desktop scenarios has little to do with performance.

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My thinking is that three spindles is a lot snappier than one -- but they're right in that the STR probably isn't going to be there and the optimation is all wrong for the desktop.

What are you planning on doing with this storage?

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Most definitely the IDE drive would win.

Not only that, but after two weeks with the SCSI drives, you would throw them out anyway because they would drive you completely nutty with their overbearing spindle noise.

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gap has narrowed with scsi still leading seriously in access time but often a normal desktop user won't feel that as much doing what a normal desktop user does

if my little sister can feel the difference in the seek so can granny

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i can feel the difference between the DM+9 and the 180GXP... seeks are pretty noticable to me.

In a blind test I might not be able to tell depending on the system setup, but I can tell that my system was snappier with a 180gxp than it is with a DM+9... even with a fresh install on the DM+9.

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i can feel the difference between the DM+9 and the 180GXP... seeks are pretty noticable to me.

In a blind test I might not be able to tell depending on the system setup, but I can tell that my system was snappier with a 180gxp than it is with a DM+9... even with a fresh install on the DM+9.

well D'UH, the IBM/ Hitachi drives support legacy command queing, that is up to 32 outstanding transactions.

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I dont think my controller does though. It is an ultra 100 with old firmware I think. It runs great and with low CPU usage so I have no need to update.

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Which would be faster in which situations:

3 Seagate ST39175LW Ultra2 7200RPM 9.1 GB SCSI disks in RAID 0 on a DPT SmartRAID Century PM2654U2-R controller.

or

A new 8MB cache, ATA-100 IDE drive.

I figured this would be the best place to ask.  B)

The question can't be answered as stated.

The 3 drive RAID0 will have a sequential transfer rate that's the aggregate (sum) of the rates of the 3 drives (assuming they're all the same type drive). That sum could easily add up to more speed than a single ATA drive could hope to muster.

But, as pointed out by others, STR isn't the entire performance story. Depending on seek times, the OS, and the applications you're running, the ATA could easily be capable of outperforming the array.

If the 3-SCSI-drive array has an STR that's as fast or faster than the ATA drive, and the seek times of the SCSI drives are as fast or faster than the ATA drive, the RAID array will probably be equal to or better than the ATA (depending on the OS and applications). If any of these conditions aren't true, it's anybody's guess.

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sechs,

Three spindles are only faster than the one under high, random queue depths (higher than exhibited under desktop usage, more random than exhibited under desktop usage), and if the requested data is distributed across three platters (which given locality is not as likely as one might think). Given the localization that is characteristic of desktop access patterns it is possible (likely) that splitting the data across three spindles will actually slow everything down.

Do well.

Jonathan Guilbault.

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The most important thing has not been addressed yet!

The HBA itself. Those DPT HBA's were very slow in RAID0. Like the Adaptec 2100, RAID0 should be called JBOD with stripes.

Those old SCSI disks will be hot, noisy, and slow on a desktop. That HBA is ultra2 not ultra 160. Either way the peak STR will not come close to approaching 80MB/S let alone 160 if that were possible.

A fast HBA makes all the difference in the world but you (generally) do get what you pay for...

Cheers!

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