Raid5 performance issues

[alex.angel]

Build following system at work (I'm a junior SA on co-op placement):

Dell Precision 410
-Pentium 2, 256MB RAM, 10/100 onboard NIC
-4x Maxtor Maxline 250GB SATA 7200RPM drives
-Promise 2410SA sata-raid controller

Built the array as RAID5, 64kb cluster size, using all 4 disks. Made a 20GB partition for Windows 2003 Enterprise Server, with the remaining (bit more than 650GB) as an empty ntfs partition.

Wanted to check i/o perf to make sure the array was up to snuff, and I get...crap. 26MB/s write in SiSoft Sandra drive benchmark (latest) and 65MB/s read. These results are awful! I might've chalked them up to "software RAID on a slow cpu" but the 2410SA is a hardware RAID card so this doesn't fly. I checked to make sure it's not a compressed filesystem, enabling/disabling write caching doesn't affect the results. I tried the latest winbench (as storagereview.com uses for their reviews) and the server benchmark pegs me lower than a single 80GB drive!

My boss wants to know what the hold-up is with my storage array work .this machine will let me test out some fancy-shmancy network storage system (ok nothing fancy, just DFS) and once I work the kinks out we're going to a much, much larger storage setup (thinking of using a few Promise 15-drive SATA-SCSI 3U boxen on a SCSI card) but I'm stymied by this performance anomaly. Any help/suggestions?

 

[ambit]

I'm going to say that's about right for RAID5 reads and writes.\
Are you sure that's a Promise card? I see it listed as an Adaptec everywhere i'm looking.
That card was one of the worst performers here:
http://www.tomshardware.com/storage/20040625/sata-raid-11.html

 

[defakto]

Well i wouldn't have put the windows install on the raid array, but that's total personal preference.

I would play around with the cluster sizes to see how that would work. Also, write performance, unless you have alot of cache, is going to be nothing impressive with raid 5.

 

[ambit]

Well i wouldn't have put the windows install on the raid array, but that's total personal preference.

And i concur. The IDE RAID5 based file servers i have (4 Win2003 machines) are all SCSI boot, 3Ware R5 arrays.
I know i read somewhere from MS that you shouldn't boot from R5, if i can find it i'll link it.
[edit]
Not really what i was looking for but here. "Operating system files and boot files cannot reside on the RAID-5 disks." I know they're talking about software raid, but i do find it interesting that you can boot from a software RAID1
[edit again] n/m, the knowledge base has too many conflicting articles. some say do it, some say don't. Typical MS

 

[alex.angel]

Oops yeah it's an adaptec card sorry.

Yeah I wouldn't have put the windows install on the array either but I was told to so no dice. I just found it kind of funny, xbit labs did a writeup on the card and it seemed to just scream speed.

Oh and booting from software RAID1 shouldn't be too hard considering it's just mirroring. The OS can init the 2nd disk and bring them to an identical state rather quickly.

 

[tiebird321]

what speed processor are you running???
is it really a P2?

if your running a p2 system
then your only running 32bit 33mhz card slot
wich has a total theoretical bandwith of 133MB's for all pci cards
so 60MB's sec is pretty resonable in that case

i use something very similer
using a similer card in an dual MP2800 system with a pci-x slot
and 4 80gb IBM 120gxp drives i have seen over 130MB's read
and up to 90 write
thats with using contigeous large files and 512kb clusters
was running freeBSD

 

[cbh]

If I can just tag onto this thread, I'm also seeing not entirely impressive performance with a 2410SA (slightly different RAID setup, I'm using RAID-10 on 4 Hitachi 7K250 drives, all write-back caching turned off for obvious reasons; the system is a Opteron 248/Tyan S2882). The read speed is bad enough, maxing out at 75MB/s whatever configuration I use, but it's the write speed that I find surprising, which I can't get to go above 7MB/s. I thought it was just what I was seeing coming from an entirely SCSI world and that's what I have to live with if I use SATA, but having seen this thread, I'm wondering if I might not be better off just binning the 2410SA...

Anyway, I don't want to try to steal this thread (should this question have its own?) so I suppose this is just for info, but if anyone does have any ideas...