What will happen if I try RAID 0 on (three) identical disks?

fishquail

Distinguished
Mar 5, 2006
226
0
18,680
0
I want the best possible performance for video editing HDV. I have (three) 500gb drives... I overheard you could do this...

I have done a sucessful RAID-0 on two disks before but...
What will happen if I try a RAID-0 on (three) identical 500gb SATA II disks? > Will I get improved performance over a two disk RAID array or will performace stay the same as a 2 disk array? Should I stick to 2 disk arrray? I wonder if my Motherboard, which supports raid off the Nvidia chip of some sort will let me do a 3 disk RAID-0?
------

System specs:
3 western digital SE16 500gb SATA-II hard drives.
MB: Tyan Thunder K8WE
CPU: Dual Opteron 270s
RAM: Corsar 2GB ECC.
Video card: Quadro FX 560
system drive: Western Digital 250gb on IDE channel.
Sound card: Audigy 2 ZS.
 

Robc1880

Distinguished
Jun 13, 2002
524
0
18,980
0
You will get better speed because the 3 hard drives would be sharing the load instead of just 2. Programs might load a tad faster, also levels in games would load faster, but i doubt it would be worth it to buy another just for the slight increase in speed. If you already have it and you have a backup solution i would suggest go ahead and give it a shot.
 

nukemaster

Titan
Moderator
Mmmmmmm more speed....

Just to try, i think when my ram comes in...i got 3 120's to test on :)

it should give a boost....as in 2 120's give lets say 60-90
3 should be like 90-130ish.... but thats only a guess....also depends on the nvraid.....

As said above....make sure you have good backup....1 drive goes...they all do....well the data does...not the drives....

Enjoy the speed..
 

vic20

Distinguished
Jul 11, 2006
443
0
18,790
2
There would be a significant boost in performance, but many new onboard and inexpensive pci raid cards are now limiting stripes to 2 disks.

When the Promise Fasttrack 66 cards came out, you could actually do a 4 drive stripe. The 4 drive didn't add much performance over 3, but it was nice for bragging rights.

I would imagine they are starting to limit raid to 2 drives so they can sell premium priced raid cards that support more.

Also, keep in mind the more drives you add to a stripe, the more you multiply the chance of data loss.

One drive fails, you're hooped.

I would guess 3 drives might be a little asynchronus. Could be wrong, but I think 2 drives would share bandwidth and 1 would have its own. I think every 2 sata ports share bandwidth.
 

SciPunk

Distinguished
Dec 15, 2005
271
0
18,780
0
And if you add enough drives, you will have all your data before you even request it !!

Well actually there will be a point of diminishing returns. The idea is to read from one drive while the next drive is moving it's drive head on to the next chunk of data. Thus always having one drive doing some i/o while the other drive is seeking.

So if a two-drive setup is already fast enough to keep up w/ the re-positioning of the next drive's read/write head, then you will see no benefit at all. If there is still a lag between reading/writing on the one drive, and the re-positioning of the drive head onthe 2nd drive... then you may see an increase... but don't expect read/write times to decrese by a 1/3. All you will make up is the time between the last bit read/writtien and the time it takes to finish re-positioning the drive head on the next drive.

But don't forget, this is risky risky risky. Striping is already risky... you double your chances of having a drive falure destroy your precious data. Now you're chances for catastrophy are trippled (from a single drive scenario); or 50% higher than a 2-drive scenario.

Be sure to have a backup system that can accomodate frequent backups of all 1.5 terrabytes.
 

hball

Distinguished
Jun 10, 2006
86
0
18,630
0
You will see a slight increase in performance with 3 disks in Raid 0. I am currently running 3 74 gig Raptors in Raid 0 for playing BF2 and I am getting into the server (first round) before (3-4 seconds) people running 2 74 gig Raptor Raid 0 setups.

If you wish to later pull one of the disks from the array then you better run them in Raid 5, where you can hot swap drives.

hball
 

Codesmith

Distinguished
Jul 6, 2003
1,375
0
19,280
0
You'll have 1.5 TB of very fast storage which is always nice :)

You will also lose up to 1.5 TB of data if as soon as one of those drives goes bad which might not be so nice :(

If you plan on backing up to DVD it will take a lot of discipline.

--

I have between 2 and 3 TB of data backed up to DVD. If I had a 1.5 TB array at least 1 TB of that would still be on the array waiting for me to burn it to DVD.

If you suspect you will run into a similar problem I would consider 2x150 Raptors.

But I am guessing that you plan on using the array just for temporary storage/editing of HD video files, so you should definitely proceed as planned.

--

PS those 500 GB Western Digital Drives might very well be the quietest 3.5" drives ever produced. They beat the Samsungs in Seek noise in all the reviews I have seen.
 

zenmaster

Splendid
Feb 21, 2006
3,867
0
22,790
3
OK, It's a pet peave of mine but the Term RAID-0 should not exit.
It should be NAID-0

Raid means - Redundant Array of Independant Disks.
Let's make that "N"on-Redundant.

Please warn me to have skipped my Coffee or M-Dew for the day before thinking about a three drive "NAID" setup.

Be sure to Ghost your system to a storage location.
You will need it.
But It will Rock While it Lives :>

If you really want to do this, consider getting 5-Year warranty Drives.
The Raptors are designed to be really reliable.

I just shudder at 3 Raptors in Raid 0.
Fast!
 

chaynz

Distinguished
Jan 29, 2006
17
0
18,510
0
(EDIT: I'm about blind; this post is from September!)

Coming from someone who has been doing RAID ever since its inception, the only limiting factor in speed for a raid 0 array is the maximum transfer rate of the interface.

For instance, let's assume that SATA 300 (SATA2) has a maximum transfer rate of 375MB/sec (which, mathematically, it does). You can stripe hard drives until you reach that ceiling. Additional hard drives may not improve your SEEK times, but your data transfers will skyrocket. As always in a RAID 0 array, if one drive fails, you loose ALL of your data, since it is divided equally into 64kb (unless you specify otherwise) blocks on each drive. If you want to upgrade an array, you must start all over, otherwise no bennefit will be seen except for data written AFTER the upgrade (if you manage to resize the partition).

Kudos on the "NAID!"
 

darkstar782

Distinguished
Dec 24, 2005
1,375
0
19,280
0
No, it doesnt.

3,000,000,000 Bits per sec signalling rate.

8B/10B ECC encoding, = 2,400,000,000 data bits per sec.

2,400,000,000/8 = 300,000,000 data Bytes per sec.

(300,000,000/1024)/1024 = 286.1 MiB per sec of data, not including error correction info from the 8B/10B encoding.

Also, unless you have an unusual SATA port multiplier (like the Silicon Image controller on the P5W DH, about the only common example of this), there is 286.1 MiB/sec PER DRIVE, not OVERALL, so even a 50 disk array wouldnt be bottlenecked by SATA.

However, it is common for the onboard controllers to only have a PCI-E x1 connection to the rest of the system, giving approx 250 MiB/sec of bandwidth here. PCI-E x8 and other high end SATA controllers dont have this limit. (well, the limit is about 2 GiB/sec each way....)
 

chaynz

Distinguished
Jan 29, 2006
17
0
18,510
0
Here, I'll let your comeback, Darkstar782, slide just because I am incapable of reading, too, and I sometimes mistake a "B" for a "b."

The interface is 3gigaBITS per second, not gigaBYTES per second. Since there are 8 bits in a byte, the correct formula is 3,000,000,000/8 = 375,000,000 (3Gb/sec divided by 1 byte [8 bits]) for a correct maximum theoretical transfer, not including ECC. For ECC, you'd simply include the 8bit/10bit parity information into 3Gb (3Gb + 8/10).
 

darkstar782

Distinguished
Dec 24, 2005
1,375
0
19,280
0
?

3,000,000,000/8 = 375,000,000 Bytes/sec, as you said.

375,000,000*0.8 = 300,000,000 Bytes/sec, after the encoding is taken into account.

300,000,000 /1024 = ~292,968 KiB/sec

~292,968 /1024 = ~286.1 MiB/sec, of actual measurable data transfer.

So you agree with me? After all it makes no difference if you throw out 2 bits in every 10 or 2 bytes in every 10, although as far as I know the B in "8B/10B" should really be "b" as it is applied at the bit level and not the Byte level.
 

choirbass

Distinguished
Dec 14, 2005
1,586
0
19,780
0
well... im not sure if you were joking or not, but yes, 3 drives in raid 0 is completely feasible and possible. as long as you have a minimum of 2 drives, youre good to go, and any additional drives are just there for added performance (and capacity), so having an odd or an even amounts of drives, wont matter.

also, with nvraid on nforce motherboards, i believe you can use both pata and sata controllers in the same raid array, having a potential 8 drives in use with just those controllers alone (though some nforce motherboards support more drives than that even)... but im sure you at least want an optical drive installed... so maybe a max of 7 drives then, lol... having them all in raid 0, that sure would generate a lot of heat though.
 

zenmaster

Splendid
Feb 21, 2006
3,867
0
22,790
3
I would get an externa USB Optical drive an just connect it to create ISOs and attach them to my 8 Drive NAID-0 Setup.

Then I would just run everything from the ISOs instead of Optical drives.

If you got it, use it.
I suspect you will have 2-4TB of space in that 8 drive NAID :>
 

choirbass

Distinguished
Dec 14, 2005
1,586
0
19,780
0
yeah... had 4 raptors running in raid 0, but, it really did generate alot of heat, so they needed proper cooling, which ended up making too much noise as well... so, i just cut it back down to 2 raptors in raid, temperature dropped, noise decreased, and so the other 2 are just sitting unused now, lol.

one of the unused ones is oddly subpar though... slower access times than the rest, and slower transer rates too.
 

Similar threads


ASK THE COMMUNITY