SATA RAID arrays - A quick question

[gobbo]

Hi guys,

I'm in the process of designing my new PC and have decided to go for a RAID array consisting of two WD Raptors in the 76Gb size. If I go for a RAID 0 array with these two drives, it's my understanding my total capacity will be 76Gb, but someone told me that the equation to work out disk space is:
(Size of smallest drive * no. of drives), which would equal around 140Gb.

If anyone can help me out and let me know what capacity I will get overall it would be apprecaited!

[Rythmic]

You've been informed correctly - RAID 0 will give you ~ 140GB.

RAID 1 (mirrored) will give you 76GB.

[javalord]

Please have a look on storagereview's FAQ about raid 0. 2x failure risk is not worth 10-20% performance gains overall.

[Wam7]

Also backing up Javalord. Think carefully before following the hype of RAID0. Look at Anandtech as well. For normal desktop use and games you will not notice the difference as there is hardly any. I have two RAID0 array (Raptor RAID0 and 7K250 RAID0) in my machine but that's because I do a lot of video capture which benefits from a lot of through put. Even still I'm going to take my hard drives out of RAID0 and run as single drives as I don't need the speed as the drives are fast enough to run as singles. I've also had the odd scare of stripe failure and it's not always easy to back up 240 gigs worth of stuff.

[Firelord]

I run 36GB RAPTORS in RAID 0 and I can notice the performance difference, I can see the difference between single and raid'd drives.

Never a disk failure or stripe failure Basically I use my RAID drives for OS, Programs and no data at all apart from temporary ISO's to speed up encoding

Theres nothing to worry about running RAID as long as you don't store essential data on them

[Spud1]

i agree with firelord

i use 2x120 gig disks in my raid0 array, never had a problem with disk failure. The stripe does fail occasionaly but its simple enough to just re-stripe it and you dont lose any data. If a disk fails then fair enough i will lose my data, but thats the same with any computer..if a disk dies you lose the data. Just because your running a raid0 array doesnt make the discs break faster...2x the risk of failure is overstating the risk a bit tbh

[TooNice]

For the typical desktop usage, the main advantage is really the boot up speed.

To be fair though, HD nowadays *are* relatively solid. The odds of losing everything if something goes wrong *is* doubled with RAID 0. Of course, if the odds of a HD failure is 0.000001, then a doubling in that doesn't mean very much, and some might find the higher benchmarks/boot up speed worth it (I doubt that many people really use seq. transfer intensive applications to be honest). One person not ever getting a problem, of course do not say very much. Just like one person who encounters a dead drive do not really say much about the overall quality of a drive manufacturer.

Myself though, I've decided to do without RAID (0). If I really want to set up a system with RAID, I'd probably pick RAID-5. I'll usually tell people that what they get from going RAID-0 is -nowhere close- to what synthetic benchmark will show.. But if they want a tiny performance increase, or simply bragging right, then go for it..

[Vimeous]

If you have the cash RAID 0 + 1 for ultimate performance & speed.
RAID 0 is fast when writing large quantities of contiguous data as it writes half the data to one disk and half to the other. Because both drives can write simultaneously this theoretically doubles the write speed. In reality small files will only get written to one disk so you'll only see a dramatic difference in performance when transfering large chunks of data.
Read speed is entirely dependant on the abilities of the RAID controller to re-integrate your data into usable chunks. The harddrives will just push data to the controller as fast as they can.

Think how you use the drives. If you're messing with big files then RAID 0 is fine but you much be prepared to back up all your data in case of stripe failure OR only use it as scratch space for temporary large files workings like film editing.
RAID 1 will give you great redundancy but only half the space for the money you originally shelled out. Hard drive failures are far less of a worry of course

It'll all depends on your usage

[Rythmic]

No matter what you choose - make sure you backup!

Seriously any data should be backed up, no matter which RAID variant you choose. I've seen a server with RAID 5 (over 5 disks with 2 online spares) get knocked completely out when it's PSU went (the server was about 7 years old... but you know what companies are like with replacing these things).

I personally go for RAID 0 on my main box (I like the boot up speed), and RAID 1 on my file server - and I also back up to DVDs

[StormPC]

If you use RAID'ed Raptors you should consider a PCI RAID controller on a motherboard that locks the PCI buss, especially if you overclock at all. It will be faster and more reliable than an onboard controller.

[Firelord]

Any nForce3 motherboard with 4 SATA ports (DFI, MSI etc) us ports 3+4 as nVidia has done a fantastic job with their implementation of RAID and is locked off

[myth]

Please have a look on storagereview's FAQ about raid 0. 2x failure risk is not worth 10-20% performance gains overall.

ok.... I have 2 36 gigers in a raid 0, which have ran for over 72,500 hours... Never a failure! However there no longer giving me a sustaind read of 102Mb/s... But I'm working on that...

[StormPC]

Any nForce3 motherboard with 4 SATA ports (DFI, MSI etc) us ports 3+4 as nVidia has done a fantastic job with their implementation of RAID and is locked off

Actually most onboard controllers suck and they are not locked. Everybody says SATA ports 3 and 4 are locked on the MSI K8N Neo2. BULL$HIT!!! My Raptors wouldn't allow anything over 215 FSB which is unacceptable to even the beginning overclocker.

If you don't overclock the NF3 onboard RAID is very fast. If you overclock at all and you are not really fond of loading Windows every other day then get a Highpoint Rocketport RAID controller. They're the best!

[Firelord]

Well thats funny I am running the system in sig (DFI, 3400+ Raptors etc) at 8*350 and running of SATA 3+4 so yes it does lock it and I know lots of people that can report the same....

[StormPC]

My DFI locks also but the MSI K8N Neo2 (and most S939 boards) has problems running Raptors in RAID 0 on the nVidia controller. You'll save yourself a lot of headaches using a PCI controller for SATA if you are overclocking.

Sorry, I should have said "not ALWAYS locked" rather than saying "not locked".

Just for fun try running your system at 250x11 with your memory running 500MHz and see what happens. Noticed your memory in your 2k1 compare is at only 410MHz.

[Rabs]

My K8N Neo Plat + Raptors are fine on SATA 3+4 and my system is at 220 (see below). Dont forget to set up your block size on your raid array to 16K not optimal (64K).