RAID 0 with 3 drives vs. RAID 0 with 2 drives

Question

Hi,

I have my XPS 720 currently in RAID 0 with 2 drives. I have a spare 500gb drive that will work fine in RAID. Will I see much performance increase by using 3 drives or is it just a waste of time that just increases my chances of a destroyed array.

Cheers

Nick Bowers · Answer

Hi,

Thanks for your reply.

The drive is a different brand so im not so sure if raid 5 will work. Looking on google RAID 5 should have Highest Read data rate but i am unsure of the different drives. Would i see a differance with RAID 0?
Cheers,

Nick

ronss · Answer

your 720 had the 680i chipset, awesome chipset,, i had a 680i board until recently, though i have a 590 chipset in my top rig, allmost the same as the 680i    raid 5 runs on 3 hard drives, and reccommended to use 3 identical drives   i actually think raid 5 is slower from what i read, i/0 throughput.. as far as i know ,,you can run raid 5 on the nvidai 680i chipset                                           Message Edited by ronss on 12-17-2007 02:14 AM Message Edited by ronss on 12-17-2007 02:21 AM

ronss · Answer

if they are not from the same manufactuer,, the hard drives, i would not try it...   you are sending data across 3 drives, you want the sectors,  tracks , etc to be the same on all three..unless they are not 3 identical hard drives, personally,, i would not do it...just my 2 cents worth

Nick Bowers · Answer

Hi, Ok thanks. I might just use it to do backups on the raid 0 array. Cheers

13owman · Answer

You can Mix / Match Drive size & types with no problem "In my job I do it all the time" I would use Raid 5 rather than Raid 0 Raid 5 will make your Drive redundant so if 1 fails you can replace the bad one with out any loss of Data RAID 5 spreads data/parity over all drives (no single check disk) RAID 0 will be a Striped set without parity in other words you will basically be adding the 3 drives together to make 1 large disk. It will be faster but if you lose 1 drive you lose them all plus I'm not sure how much performance increase you will see. Raid 5 is the Preferred Array for most IT professionals It adds Performance + Redundancy. The large price difference between RAID controllers is being the one who does the parity calculation. Cheaper ones like the on-board controller on the Mother Board lets CPU do all the work, expensive ones that you Buy and install in a PCIe slot lets on-board X0R processor do it, so that is why I said that the performance increase probably would not be that noticeable.

gdwrnch3 · Answer

RAID 0, in all actuallity, really isn't RAID—there's no redundancy at all. RAID 0 stripes data across two (or more) drives to maximize read and write performance. The different drives split up the read or write portions of the data in order to improve throughput. So two identical drives—200GB, say—are combined to look like a single 400GB drive. If one drive fails, you lose all your data from both drives. RAID 0 requires at least two drives.

RAID 5 needs three drives at a minimum. The data is striped across the drive, as with RAID 0, but additional parity data is also striped across the drive. This parity stripe contains checksum information on the data written. If a single drive fails, the data on the failed drive can be reconstructed from the parity stripe. A RAID 5 device can survive the failure of one drive at a time, as long as time is taken to rebuild the data fully from the failed drive with a replacement. RAID 5 read and write performance is much faster than RAID 1, but a little slower than RAID 0. Three 200GB drives would appear as 400GB (200GB is used for the parity stripe).

I haven't fooled with a raid 5 yet as I prefer the performance of the stripe.

I do however, back up weekly, and if I do any critical work, I back up that evening to one of two internal 750G WD hard disks, and an external lacie.

Message Edited by gdwrnch3 on 12-17-2007 01:09 PM

Timdrouilard · Answer

As with everything else, it all depends on what applications you use everyday rather than benchmarks.   As far as RAID 0 goes, there is no limit to the number of drives you can use (other that your controller of course), and the more drives you use, the more drives the system can read/write to at the same time so in theory, the more drives, the faster the transfer rate.   Whether or not going from two drives to three will have a noticable different for you is hard to say.

Nick Bowers · Answer

Hey, Thanks for all your replies, from what i am hearing i might just use 2 drives in raid 0 and have the 3rd for regular backups.   Although i was also wondering how would 3 drives in RAID 5 compare to 2 drives in RAID 0? Performance wise.   Cheers, Nick

gdwrnch3 · Answer

Going from two drives to three will not show a signifigant increase, and this isn't from reading someone elses article, this is from trying it.

I use a two disk stripe in three machines in the house, I happen to like it, but as fast as the new disks are today, I'm not sure it's worth it. I think a single 750, or a 4 plate 1t might be almost as fast as a stripe in the real world.

Message Edited by gdwrnch3 on 12-17-2007 08:17 PM

ronss · Answer

i run stripe 0 on this rig i am own,,use to have 4 computers , all runng raid 0....i just like the smothness that i seem to notice with raid,,seems like things just flow on the desktop.  great thread,,learned a few things about raid 5.

gdwrnch3 · Answer

haven't messed with raid 5, I really don't want to waste the drive. I use a two disk stripe, and the rest of the drives for storage and backup

XPS700User · Answer

the deal with raid O and 5 is: First lets cover raid 1 to help understand raid. Raid 1 is two mirrored drives this gives a little speed advantage in drive reading, and a disadvantage in writing to the drives. The main purpose of Raid 1 is redundancy- should one drive fail, the other drive is a complete copy of the main drive. it will take over and the system will still run. That is the process of mirroring. 0 is striping mode where data is wrote across the drives (normally in a raid of 2 to 4 drives)in blocks of a predetermined size with the drive write jumping back and forth from drive to drive. the more drives you add to your type 0 raid array the more read/write speed you will gain. There is no redundancy or data checking with raid 0 it is used for a increase in read/write performance only. Raid 5 is striping with parity. this is were data is set with and parity bit and checked when read. this will give you some gain in performance with accurate storage and reading of your data. Both raid 0 and 5 will leave your system unrecoverable if a drive should fail. another option to raid 0 or 5 is Raid 10 Raid 10 is Mirrored striped arrays with parity. that is two arrays of raid 5 that that mirror each other. This leaves a recovery option should one drive fail as the two arrays are redundant. I don't think the XPS 700 series supports raid 10

Khaoswulf · Answer

keep in mind for you to get tech support from dell they will want to make sure its in it's orginal setup as a raid 0 with only 2 drives. So if the array goes bad an yer hdds fail there might be a issue with support for it.

XPS700User · Answer

Nick, I use 2 250gb drives on my XPS700 with good results.

Nick Bowers · Answer

Hi all, Thanks for your input, im going to go with raid 0 with just 2 drives. The tech support maybe a problem as it was only shipped with one.:smileysad: Nick

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RAID 0 with 3 drives vs. RAID 0 with 2 drives

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