Raid 5 Slow Performance.

[trza2k]

Hi,

I've currently got a windows 2003 server running a 4x 200GIG IDE software raid 5 (provided by windows 2003). i've been doing some testing on this machine and have found the raid 5 write speed to be EXTREMELY slow, on large files it seems to start off fast then slow downs (i gather the parity calculations are catching up). The machine is a 1.4ghz athlon on a nforce 2 mobo with 512meg ram.

From another machine on the network i decided to do some transfer tests to test the write speed, as thats what i will primarly use it for. I used ftp instead of windows copy so i could get some consistant results. I first tested ftping to the server to a single drive in the server and then to the raid5 array and the results were:

Transferred 4 files totaling 2.36 GB in 03:40 (11,239.48 KBps) // Single ata100 disk
* this seemed to be maxing out the 100mb network

Transferred 4 files totaling 2.36 GB in 09:17 (4,464.56 KBps) // raid 5 array

As you can see the raid 5 write is very slow, now i just need to know:
a) Will a CPU upgrade help peformance (say a XP 2600+)
b) I have some weird configuration problem
c) Just buy a decent hardware raid as raid 5 software will never be fast

Thanks for your help

 

[mjz_5]

well, software raid is horrible... It would be better to spend the money (instead of a CPU) on a raid controller card.

 

[trza2k]

Cost is a bit of a issue though, $150 AUD for a decent CPU VS $450 AUD for a decent raid card. If the CPU can at least bring up the speeds to 100mb/sec network speeds i would be happy!. Just dont know if the cpu could do it though.

 

[Great_Melinko]

write speeds are some what slow on a raid 5 array from my experience. read speeds are insane though. but i agree, software raid = shit

 

[mjz_5]

you can just make them 0+1 (mirroring and striping).. you'll have less hard drive space, but you will have the speed.

 

[tdg]

RAID 5 in generally is usually fairly low on writes no matter what, but combined with software RAID making your CPU do all the parity calculations is never going to have good performance.

A upgraded CPU may help some, open up the task manager and watch the CPU load while the machine is doing some heavy writing, if it's at a high load then a upgrade here may help. But the best thing to do is go with a good hardware RAID card, it will still be fairly slow, but probably a decent increase over what you're getting now.