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hokeyplyr48
01-16-08, 05:51 PM
One of my 150gb raptors in my RAID-0 array died and for some reason Western Digital is sending me two back so i'll have a total of three hd's.

http://img516.imageshack.us/img516/813/westerndigitalmg5.jpg

^ makes sense doesn't it? recieve 1 send 2...

so my question is should i do a triple raptor raid 0 array? or should i just throw that in separately? should i put certain files on there or what?

any thoughts?

LovingSticky
01-16-08, 05:55 PM
RAID-0 is really great, if you don't mind loosing all your data. Think RAID-5 instead ;)

hokeyplyr48
01-16-08, 06:01 PM
well i use RAID-0 for the speed and i do back everything up frequently.

but i am sticking with a RAID-0 setup and i'm wondering if i should stick with just the two or throw the third one in there. would i see any speed increase?

if not, what should i use it for? like my music or program files or what? (not for storage, looking to speed things up. got plenty of space for storage, read sig)

Toss3
01-16-08, 06:07 PM
well i use RAID-0 for the speed and i do back everything up frequently.

but i am sticking with a RAID-0 setup and i'm wondering if i should stick with just the two or throw the third one in there. would i see any speed increase?

if not, what should i use it for? like my music or program files or what? (not for storage, looking to speed things up. got plenty of space for storage, read sig)
Seriously do you gain any speed at all from Raid-0 with raptor drives? Saw a benchmark comparing two raptors in raid-0 to a single drive, and there were no difference in performance between the two. :o

Edit: Found the review here (http://www.anandtech.com/storage/showdoc.aspx?i=2101&p=11)

Final Words
If you haven't gotten the hint by now, we'll spell it out for you: there is no place, and no need for a RAID-0 array on a desktop computer. The real world performance increases are negligible at best and the reduction in reliability, thanks to a halving of the mean time between failure, makes RAID-0 far from worth it on the desktop.

einstein_314
01-16-08, 06:34 PM
RAID-0 is a complete waste of time on a desktop computer (especially with Raptors...). I used to run RAID-0 with 2 of my drives and there was NO noticeable performance difference. Now I run RAID-1 (mirror) with 2 of my drives for my documents drive. That way I don't have to backup all the time and have peace of mind that if one breaks, I still have all my data.

hirantha
01-16-08, 07:04 PM
you cant run RAID 0 with 3 drives you need, 2 , 4, 8 drives and so on... i think thats the case.

with 4 drives in RAID 0 you will see a great jump in performance.

mythy
01-16-08, 08:15 PM
Some of you need to understand this **** before you offer advice and state facts that are false

stncttr908
01-16-08, 09:02 PM
If I had three I'd run RAID5. You're not losing any capacity since you had two 150GB drives anyway. This way, when one dies again you can most likely rebuild your data. ;)

You can run RAID 0 with an odd number of drives, no problem.

mythy, why don't you correct them instead of just pointing it out?

mythy
01-17-08, 06:45 AM
I already did in another thread about the Samsung F1 Its getting pointless since no one listens. :p

lightman
01-17-08, 01:36 PM
With Raid-0 you do get better performance out of Raptors. I can confirm this quite easily.

I will run some iozone benchmarks tomorrow when I get to the office, and I will post some graphs...

PS: about RAID-5, good idea if you want safety, but bad for (especially write) performance...

mythy
01-17-08, 06:57 PM
performance for what? Are we talking I/O performance? Throughput or access time?

LycosV
01-17-08, 09:12 PM
I'd use RAID 0 on two of them and use the last one independant. Running RAID 0 on three drives is really pushing the risk envelope IMO.

I think the performance/risk ratio is worth it to RAID 0 two drives but when you throw in a third I don't think your're going to see tremendous improvement for the risk of loosing it all.

hokeyplyr48
01-17-08, 09:38 PM
awesome thanks. i'm gonna raid two and just put the third one in there.

my second question though.
can i put the "users" folder on the other raptor or does it have to remain on the windows drive?

Slammin
01-18-08, 01:23 AM
I'd use RAID 0 on two of them and use the last one independant. Running RAID 0 on three drives is really pushing the risk envelope IMO.

I think the performance/risk ratio is worth it to RAID 0 two drives but when you throw in a third I don't think your're going to see tremendous improvement for the risk of loosing it all.


That is absolutely the best answer I can see coming out of this thread.

RAID0 is always faster. Adding more drives adds more performance too, until you exceed some bus limitation, but also, adding more drives, adds more risk.


Great answer LycosV!

nemecb
01-18-08, 10:55 AM
Seriously do you gain any speed at all from Raid-0 with raptor drives? Saw a benchmark comparing two raptors in raid-0 to a single drive, and there were no difference in performance between the two. :o

Edit: Found the review here (http://www.anandtech.com/storage/showdoc.aspx?i=2101&p=11)
That's a horrible benchmark and I'm really surprised to see it on Anandtech. Why on Earth would you use multimedia creation as a hard drive benchmark? Almost every multimedia function I can think of is CPU bound, so of course the hard drive performance is going to have no impact. If anybody thought that faster hard drives would somehow make their CPU faster then they lose their geek card anyway.

For a test of pure hard drive performance I'd suggest this (http://www.tomshardware.com/2007/07/02/raid_scaling_charts/page10.html). It's the opposite end of the scale of course, purely hard drive bound not taking into consideration anything else, but it shows that RAID does actually have a significant effect on hard drive performance. Whether that will be noticeable to someone entirely depends on what they're doing, so you can't make a blanket statement that RAID is worthless.

Personally I'm looking at RAID 5 for my next system. My only real concern is that I have no idea how it performs on low-end or onboard RAID controllers. I don't want to spend $400 on a RAID controller when I could just go RAID0+1 for less. Maybe I'll start a new thread and see if anyone here has experience with that.:)

Bman212121
01-18-08, 11:58 AM
Personally I'm looking at RAID 5 for my next system. My only real concern is that I have no idea how it performs on low-end or onboard RAID controllers. I don't want to spend $400 on a RAID controller when I could just go RAID0+1 for less. Maybe I'll start a new thread and see if anyone here has experience with that.:)

From what I've seen in benchmarks it's not worth bothering with. The biggest tradeoff when using RAID5 with a software or onboard controller is that the CPU has to do the parity checks for the array. So not only would it take valuable CPU time it is going to be limited by moving data back and forth across the PCI bus to get it to the cpu. Unfortunately I can't say as I have my own experience with it so I'm sure the results may vary depending upon what article you read.

Bman212121
01-18-08, 12:11 PM
One of my 150gb raptors in my RAID-0 array died and for some reason Western Digital is sending me two back so i'll have a total of three hd's.

http://img516.imageshack.us/img516/813/westerndigitalmg5.jpg

^ makes sense doesn't it? recieve 1 send 2...

so my question is should i do a triple raptor raid 0 array? or should i just throw that in separately? should i put certain files on there or what?

any thoughts?

I'd throw it into your secondary rig. ;)

If anything it would make the most sense to just make a 3 drive array. As soon as you start using seperate drives you lose the benefits of having a RAID array.

LycosV
01-18-08, 12:54 PM
my second question though.
can i put the "users" folder on the other raptor or does it have to remain on the windows drive?

Yes. You can redirect specific user folders by either checking the properties of "My Documents" etc, or you could create a roaming profile with it stored on another drive.

nemecb
01-18-08, 02:37 PM
From what I've seen in benchmarks it's not worth bothering with. The biggest tradeoff when using RAID5 with a software or onboard controller is that the CPU has to do the parity checks for the array. So not only would it take valuable CPU time it is going to be limited by moving data back and forth across the PCI bus to get it to the cpu. Unfortunately I can't say as I have my own experience with it so I'm sure the results may vary depending upon what article you read.
Ouch, I just found one specifically addressing my question and the write speeds on the reasonably priced RAID controllers are atrocious. I'm not too concerned about write performance, but 12 MB/s is just too low, especially for the small increase in read performance. Now I just have to decide if I want to go 0+1 or have a RAID1 storage array and a RAID0 OS/games array. Decisions, decisions.:)

XDanger
01-18-08, 03:25 PM
my WEI was 5.9 with raptors striped ,dropped to 5.2 or some such when one stopped wanting to be in an array.

Raptors are all about the random access time.

Buckeye
01-18-08, 04:26 PM
I have my two Raptors in raid 0 atm...

HD Tune 2.54 Reports
Transfer Rate:
Min: 94.8 MB/sec
Max: 143.0 MB/sec
Avg: 120.3 MB/sec
Access Time: 8.2ms
Burst Rate: 107.2MB/sec
CPU Usage: 4.0%

One single 500gig WD SATA II
HD Tune 2.54 Reports
Transfer Rate:
Min: 36.1 MB/sec
Max: 69.7 MB/sec
Avg: 56.1 MB/sec
Access Time: 13.8ms
Burst Rate: 112.9MB/sec
CPU Usage: 2.3%

I have run it that way for some time and it seems pretty zippy. I ended up taking my 500gig drives and putting them as single drives and not in a raid. I would have to rehook up the 500's in Raid 0 to see what a diff it makes with thise two drives.

I have my OS on the Raptors, My Documents reasigned to one of the 500 gig dirves and programs on the other.

I decided at one point that I was not happy with raid 0 setups for my main machine because if something happens your screwed. You can not take 1 drive out and put it into another machine and recover data. It's just easyer to keep them as single drives and the fact that newer drives are simply fast enough and do not really need to be in a raid.

But as time has gone on I now have a 3 TB (4x 750gig WD SATA II drives) WHS for backups, plus a Buffalo TerraStation so backing up data is not as important to me as it used to be as it is handled automaticaly with WHS and I keep other important data on the TerraStation with manual backups.

lightman
01-18-08, 05:38 PM
Ouch, I just found one specifically addressing my question and the write speeds on the reasonably priced RAID controllers are atrocious. I'm not too concerned about write performance, but 12 MB/s is just too low, especially for the small increase in read performance. Now I just have to decide if I want to go 0+1 or have a RAID1 storage array and a RAID0 OS/games array. Decisions, decisions.:)

Keep in mind that even with high end RAID controllers it's more than possible that a purely software RAID-5 could beat the write performance of the controller (I witnessed it with a 3ware 9550sxu-12).

The pros for a hardware RAID are 1) CPU processing offload to the controller and 2) safety, but only if you have a battery backup unit (like this for the 9550sxu : http://store.3ware.com/?category=2&subcategory=6&productid=BBU-MODULE-03 ), otherwise you have to disable the controller write cache but that literally kills performance (down to 7.5 MB/s with a 5 drives array).

nemecb
01-18-08, 07:16 PM
That's funny because the benchmark that I saw had a high-end RAID card writing at like 100 MB/s. The more I think about it though the more I think I'll just go for two separate RAID arrays: one striped for speed and one mirrored for safety. After all, rarely am I going to be making changes to the OS/games drive that aren't going to be handled sufficiently by my nightly backups, but on the other hand if I work on a document for several hours some day I'd like the safety of saving it on a mirrored array so that if I lose a drive before the backup runs I don't lose those hours of work. I may have to get a bigger backup drive though since I'm looking at getting ~500 GB drives (and my backups are currently on a 160).:)

BTW, sorry to the OP for the thread hijack. I guess I should have opened that new thread.:o

hokeyplyr48
01-18-08, 09:29 PM
no it's fine, my question was answered a little while back.

lightman
01-19-08, 04:44 AM
That's funny because the benchmark that I saw had a high-end RAID card writing at like 100 MB/s.

Wait, I didn't say you can't attain those speeds. You can in fact, but only if you have the write cache enabled, and you use enough disks.

My RAID-5 with the 9550sxu and 5 (old and slow) 300GB Maxtors reaches about 55 MB/s in write, and 192 MB/s in read, with the write cache enabled. Disabling the write cache slows it down to less than 7.5 MB/s, as I said earlier.

I will let you know how speed scales with adding more drives as soon as I install the 3 new 1TB WD Caviar GP I bought. Should gain something, although I'm not sure how much.

Oh, by the way, I got those speeds with Bonnie++, with the RAID volume formatted with xfs, under linux.


Back to your specific problem, RAID 0+1 is not bad, although you loose a little of the write speed gained with the 0 because of the 1 (that is, for every write, the system has to write to both the 0 volumes).