Raid 0 or raid 5?

[hyperasus]

Ok, so I just got my Asus P5AD2-E motherboard (very nice by the way) and I see it has an option for raid 5. I currently have three 74GB WD Raptor hard drives. So my question is should I go with the raid 5 or should I stick with the raid 0. Is raid 5 going to be a huge performance loss? I like the idea of being able to just replace a hard drive if one dies without losing my data, but not if that means taking a big performance loss. What do you think?

 

[1Time]

Welcome to the forums hyperasus!

I would raid-0 two of the drives and use the other for back-up/storage.

 

[hyperasus]

Thanks for the quick response. Any particular reason why you would go with raid 0? Is raid 0 faster? By the way here is my system-

Case Lian Li Aluminum PC-V1200
CPU Intel Pentium 4 570J 3.8 GHz
Motherboard ASUS P5AD2-E PREMIUM
Memory CORSAIR DDR2 XMS2 Pro PC2-5400 with activity LEDs
Hard Drives 3x WD Raptors 74GB 10,000rpm and
2x Seagate 200GB 7200RPM SATA
Graphics Card XFX nVIDIA GeForce 6600GT

 

[kct2]

It will definitely mean some performance loss, especially with writes. The RAID5 that board supports is SOFTWARE RAID5, meaning the CPU is doing all of the XOR (parity) calculations. Every time you write to the drive these calculations need to be done, so writing a file becomes a very CPU intensive process.

That said, if you have a very fast CPU you may not notice a huge hit, but it will be there. Even hardware RAID5 controllers (meaning the parity information is calculated on the card, not the system CPU) show a performance hit when writing.

RAID-0 with raptors has been shown to do little good on a desktop computer. So I'd try a few different configurations and see what works out best. It may not be a bad idea to use RAID-1 with two of them if you are concerned about fault tolerance. I do think RAID-5 will largely disappoint you.

edit: Now I see you have many hard drives, and a VERY fast proccessor, but I still expect you'd see a performance hit. Maybe 3 raptors in RAID-0 are better than 2...worth a shot...it won't be slow that's for sure.

 

[hyperasus]

Thanks for the detailed reply kct2. I wasn’t aware that my raid 5 uses the CPU, that’s a deal breaker as far as I'm concerned. You say I could put 3 hard drives on raid 0. I didn’t know that was possible. How does Raid 0 work with three drives? Is Raid 0 with three drives faster then Raid 0 with two drives?

 

[kct2]

It works exactly the same as with 2 drives, except the data is striped over the 3 drives instead of 2. It should be faster. If you haven't seen it before, give this a read:

http://www.storagereview.com/guide2000/ref/hdd/perf/raid/levels/singleLevel0.html

 

[Electron Chaser]

Raid 5 can be faster if it is not software driven. Compared with disk space you haver less wasted space for redundancy versus a Raid 1.

 

[Sonny]

Thanks for the detailed reply kct2. I wasn’t aware that my raid 5 uses the CPU, that’s a deal breaker as far as I'm concerned. You say I could put 3 hard drives on raid 0. I didn’t know that was possible. How does Raid 0 work with three drives? Is Raid 0 with three drives faster then Raid 0 with two drives?

Well there are a few things to watch out on RAID0 systems. You have to think about PCI BUS saturation & sharing. The controller that you will choose will play an important role just as much as anything else in the storage setup.

If you use the SI controller you will definitely be on the PCI BUS which will be sharing with the Dual Gigabit LAN & the Audio. Will PCI Express offer enough bandwidth to not be a bottle neck? Since there are limited number of people running this combination we don't have reliable data on it to be able to advice properly, It would be something to do to closely document your results to start something for future reference.

If you use the ICH6R you won’t have any PCI BUS issues. Its older brother the ICH5R was basically the benchmark for any PCI BUS bottlenecked setups. We've seen numerous reviews on RAID0 setups & most never caught on with their PCI BUS issues. Asides from bandwidth considerations you also have latency issues that pretty much decide how efficiently the Array will work. You almost never really see a review mention these & the later is why properly setup RAID0 arrays do perform beyond a single drive.

A 3 HDD array will pose a few more issues that you should be prepared to deal with, increase latency due to the spanning of data onto more HDDs & higher CPU utilization. Again RAID0 needs to be setup & tailored to the user. no single setup will result in good performance. There is a very large percentage of poorer performance when setup wrong.

 

[hyperasus]

What if I bought another raptor and did a raid 0+1 on the ICH6R controller? I would be giving up some space but I can live with that. Is 4 drives on the ICH6R going to work the controller to hard and effect the performance? Thanks for all your help guys.