RAID 0 or RAID 1?

[gustav]

i know several others have asked whats the best and i have two but i havent recieved the best answer from reading other posts. this summer im considering buying a second 74gb raptor to put into raid with my current raptor. all i will put on the setup is the OS and all my apps and nothing else. i want the best read times i suppose. i play games a lot and i want the maps to load faster. for this i ask which is better: RAID 0 or RAID 1? i understand RAID 0 has its risks. im will to take these risks. i know it gives in theory double read and write times with slower access times. all i know aboput raid 1 is that you need two drives but you only get the space of one since all data is put on both drives. the question is, which will load programs the fastest and other things such as maps in games?

my second question is for this application, which stripe size is best? smaller or larger?

thanks for your help and patience in advance.

[skahtul]

Allready explained it HERE (http://www.ocforums.com/showthread.php?s=&threadid=288386) .

Edit:
Note to self: Don't just post, look around first....

You can not compare the two because they are not the same thing. READ THIS (http://www.acnc.com/04_01_00.html) . Click on the different RAID configurations and it will tell you everything you need to know.

Read about it, RAID 1 is the slowest out of all types of raid.

[I.M.O.G.]

EDIT: Keep reading in this thread, this isn't all right.

RAID0 is the only RAID level that ever increases performance.

StorageReview will tell you that 16k is the ideal real world stripe size, but a higher size like 64 will help you in some benchmark scores. I would stick to 16k, benchmarks aren't worth it.

BTW StorageReview has very good information on that subject - they are excellent about getting accurate results and being technically on point. They explain the difficulty of getting true benchmark tests from HDD's... The only way to do it is to buy very expensive software I believe, or use a custom app that is carefully coded (that is what they use for their reviews I think they say)

[nikhsub1]

Originally posted by skahtul
Allready explained it HERE (http://www.ocforums.com/showthread.php?s=&threadid=288386) .

You DO NOT GET any performance from Raid 1, that is for data integrity, NOTHING ELSE! If anyone says different then they are wrong.

You can not compare the two because they are not the same thing. READ THIS (http://www.acnc.com/04_01_00.html) . Click on the different RAID configurations and it will tell you everything you need to know.

Read about it, RAID 1 is the slowest out of all types of raid.
Some of this is just wrong. Raid 1 (mirroring) will benefit from fast READS, faster than a single drive. Why? Because it reads the data from both disks, almost like raid 0. Write times on raid 1 are what are slow(er) because it must write the data twice. A quote from your link: "Twice the Read transaction rate of single disks, same Write transaction rate as single disks." So please don't say that raid 1 is the slowest and whoever says it is is wrong.

[kct2]

Originally posted by IMOG
RAID0 is the only RAID level that ever increases performance.


That isn't true, and it isn't nearly that simple. It is a matter of balancing random and sequential read/write performance, and fault tolerance. RAID0 may provide the most even performance increase over a single drive, but all levels provide a performance increase in at least one aspect.

You mention storagereview, and they have a great RAID primer. http://www.storagereview.com/guide2000/ref/hdd/perf/raid/levels/single.html

[skahtul]

Originally posted by nikhsub1

Some of this is just wrong. Raid 1 (mirroring) will benefit from fast READS, faster than a single drive. Why? Because it reads the data from both disks, almost like raid 0. Write times on raid 1 are what are slow(er) because it must write the data twice. A quote from your link: "Twice the Read transaction rate of single disks, same Write transaction rate as single disks." So please don't say that raid 1 is the slowest and whoever says it is is wrong.

I stand corrected. Sorry for saying it in such a stupid way.

[FireMogle]

Originally posted by kct2


That isn't true, and it isn't nearly that simple. It is a matter of balancing random and sequential read/write performance, and fault tolerance. RAID0 may provide the most even performance increase over a single drive, but all levels provide a performance increase in at least one aspect.

Lets say RAID 0 is the only form of RAID who's sole purpose to increase performance, while neglecting the Redundancy aspect.

[gustav]

RAID 0:

Random Read Performance: Very good; better if using larger stripe sizes if the controller supports independent reads to different disks in the array.

im basicly looking for the best read times. i want my apps to load up fast (particularly maps in games). you (IMOG) say 16KiB is best stripe size....but it says if you use a larger stripe size the read and write speeds will increase.

the 74gb raptor has a seek timne of 4.5ms, so how much worse would it be with raid 0 and how would this affect performance?

[nikhsub1]

Originally posted by gustav
RAID 0:

Random Read Performance: Very good; better if using larger stripe sizes if the controller supports independent reads to different disks in the array.

im basicly looking for the best read times. i want my apps to load up fast (particularly maps in games). you (IMOG) say 16KiB is best stripe size....but it says if you use a larger stripe size the read and write speeds will increase.

the 74gb raptor has a seek timne of 4.5ms, so how much worse would it be with raid 0 and how would this affect performance?
If all you care about it read times, go with raid 1. The read time is almost as good as raid0. I just setup 2 74GB Raptors in raid 1 and the drives are very fast, they feel as fast or faster than my 2 36GB Raptors in raid 0. If you don't care about redundency, go raid 0.

[skahtul]

Originally posted by nikhsub1

If all you care about it read times, go with raid 1. The read time is almost as good as raid0. I just setup 2 74GB Raptors in raid 1 and the drives are very fast, they feel as fast or faster than my 2 36GB Raptors in raid 0. If you don't care about redundency, go raid 0.

After seeing everything that everyone said in a few posts on this subject, I re-did my system in RAID1. It seems to be working just as fast. I can not "tell" any difference (which is pretty subject without benchmak stuff ect. anyway). I think I will try out RAID 1 for a while.

[I.M.O.G.]

Thanks for the info guys, editted previous comments.

I was under the impression that raid levels other than 0 had theoretical performance advantages, however they could not be realized due to processing/operation overhead? I am thinking this is just wrong now.

It's been too long since I have read the RAID information, and will keep my foot out of my mouth in the future. I always appreciate having a friend to watch over my shoulder though. Thanks guys. :)

[skahtul]

Originally posted by IMOG


It's been too long since I have read the RAID information, and will keep my foot out of my mouth in the future. I always appreciate having a friend to watch over my shoulder though. Thanks guys. :)

The advice I now Post By.

[I.M.O.G.]

I've recently been doing more close reading of the storage review site, and it seems that the best stripe size they recommend is actually 64 or 128 for real world performance. They say that lower settings can improve STR performance in benchmarks, but it doesn't translate to real world results.