=[[Best RAID in Your Opinion]]=

[kenji]

What is the best raid in your opinion. Something for home use which would require high read and write and be fault tolorent. In my opinion RAID 5 would take the cake. I am a gamer so high read speed is important. I also have alot of data moving around and stored which is really important to me. If anyone knows a raid that would work better for this situation please do tell.

whats your choice?


PS: my opinion is baised of of the information from here:
http://www.acnc.com/04_01_03.html

 

[Pla]

raid-5 is good for stripping and parity but it has big penalty for writing small portions.

If you write a block which is less then the stripe size the speed will be half the speed of a single drive.

If you write block bigger then (N-1)*stripe size the speed will be (N-1)*drive speed. In the case of 4 drives it will be 3 times faster then single drive.

So if your moving data is less then 3*stripe size you will have big penalties.

Another option to consider is stripe + mirroring.
You need 4 drives and the size is the size of 2 dirves. (raid-5 will be the size of 3 drives).
So you will have less size but it doesn't have any penalty for writing small blocks.
Also the write speed is less - it is only twice of a single drive.

Let me compare them here for 4 drives of 100GB and speed 50MB/s and stripe size of 16kb:

raid 0+1
capacity: 200GB
read speed of block bigger then 64kb: 200 MB/s (it reads from all 4 drives)
read speed of block smaller then 16kb: 50 MB/s
write speed of block bigger then 32kb: 100 MB/s
write speed of block smaller then 16kb: 50 MB/s

raid-5
capacity: 300GB
read speed of block bigger then 64kb: 200 MB/s
read speed of block smaller then 16kb: 50 MB/s
write speed of block bigger then 48kb: 150 MB/s
write speed of block smaller then 16kb: 25 MB/s

Hope this is more helpful then confusing...

Also raid-5 requires more expensive card...

 

[attack]

I'm sorry Pla, those numbers are just theory, RAID 5 blows in writing at all speeds. A 5400rpm laptop HDD on ATA66 will write faster (from 1k to 10mb files) than 4, 10k U3 SCSI drives in RAID 5 with a 256mb controller.
The test setup was on a compaq DL380 with dual 2.4 xeons and a gig of PC2100 ECC.

And that is with over 1000 bucks in disk drives! 4 IDE 8mb 80gb ATA133 maxtors in a 4 channel controller will peak around 3-4mb/s write speed. With a RocketRAID 404 controller on a 2.4ghz Tbred and memory at 220mhz FSB (again my personaly first hand results).

For home use I would get 2 raptors run em in RAID 0 and use windows XP backup utility to backup your drives at night onto a cheap 80gb IDE drive. That will give you excellent performance, or if you got even mroe cash get 2 U3 15k SCSI drives in a RAID 0 and back em up to a inexpnsive IDE drive.

 

[Pla]

Yes it was just the theory.

ajrettke - thanks for sharing your experience.

I knew that reality will be less then the theory but didn't even think it could be that bad...

 

[attack]

heh your telling me, i read up and thought...damn raid 5 would be sweet...I bought that IDE setup thinking to run RAID 5....kinda ****ty, I tested the SCSI a couple months later at work. The SCSI really wasn't that bad since most stuff done with servers is reading and not writing, which both IDE and SCSI RAID 5 was very close to RAID 0 performance. But SCSI RAID 5 is outragously expsnive, and IDE RAID 5 is very dissapointing.