ButtonPuncher

Slow file copy time using WinXP raid5

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This is driving me nuts...

I have a raid5 software array setup under WinXP. When I try to copy a large file to the array it starts off blazingly fast with about 18% CPU usage. For the 8.5GB file, it initially says 2 minutes to copy. It copies for about 8 seconds and then it slows down drastically. The copy time shoots up between 70-95 minutes and the CPU usage drops to 1-3%. If I let it sit there and copy, everyonce in a while, the CPU usage will jump back up to 18-20% and the time will drop back down to under 2 minutes.

What is limiting the file copy speed?!? Why is something in Windows telling it to give it a lower priority?

BTW, the is from a two 400GB Raid 0 config using a Netcell raid card copying to 5 250GB IDE drives on two Promise Ultra133TX2 PCI cards. Everything is on my shiny new Supermicro PDSME+ mobo running a Core2 E6400 with 2GB of ram.

I was thinking that this was somekind of cache issue, but the fact that it jumps back up in speed randomly has to point to some kind of thread priority problem.

Thanks in advance for any help.

Ben

Edited by ButtonPuncher

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A possible culprit with poor performance on dynamic disks (out of the default poor implementation) could be fragmentation, altough I haven't been able to verify that.

Generally, my grief with dyndisks "raid" has always been crippled performance for big files since at least windows 2000 and absolutely horrendious "speed" on small and fragmented files (<1MB/s, or even <0.3MB/s).

For example, switching to Gb Ethernet didn't yield any increase of speed for big files for me.

Edited by jamieshea

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I've been experimenting some more and something else is not right. It seems that the "Tom's Hardware raid5 hack" doesn't work properly with XP Pro 64 bit. Everytime that I reboot the computer, I have to resynchronize the array. This leads me to believe that the throughput problems are somehow related.

I'm suprized that nobody makes Raid software for WinXP. I'd spend $50 for some software that did raid better than Micro$oft can.

Oh well, off to Newegg to find a decent PCI-X IDE raid controller.

Edited by ButtonPuncher

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There's really no use for software RAID 5 on a mere desktop OS. Even on a server I wouldn't use it. Buy a controller instead. At least you can boot of a controller, you can't boot off a software RAID 5.

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