IDE RAID setup/peformance

[Guest]

I like to set up RAID on my new system. I understand that RAID 0 can use two harddrives as one and the access/performance is faster right? So if this is the case, do I need to use two identical harddrives? RAID 1 duplicates the single harddrive onto both so for example, if I have two 9 gig harddrives, I only have 9 gigs available vs 18 gigs right? If I have two identical partitions on the two separate drives, can I have half of those partitions be used as RAID 1 and the other halves at RAID 0? So this gives me 9 gigs for use at RAID 0 and another 4.5 used as RAID 1? (4.5/4.5 as RAID 1 and 4.5+4.5=9 at RAID 0) So this totals up to 13.5 gigs to be used right? If I'm not worried about my HD's failing, I should just use the two drives at a whole 18 gigs which would still give me the best performance right? Thanks for any input.

 

[Guest]

Try this link I found on the KT7 FAQ:

<A HREF="http://www.pcguide.com/ref/hdd/perf/raid/index.htm" target="_new">http://www.pcguide.com/ref/hdd/perf/raid/index.htm</A>

Mike

 

[Kodiak]

I wouldn't really mess with the whole half raid 1 / half raid 0...
true, having raid 0 on two hard drives (yup, they have to be identical), is technically a lot more prone to error then just single drive -- simply because if you experience a total failure of *either* drive, you've lost the whole RAID system, i.e. one cannot operate without another.
Now to me personally,
a) in my 12 years of PC computing, I've never had a HD fail completely on me. (Well, there's that one time when I was putting a system, dropped a screw on a working HD and fried the whole darn thing but... that's a whole other story
Individual experiences may vary, but generally, my HDs have been reliable...
b) I don't have CRITICAL data. Sure, it's a nuisance if I have to rebuild a system; but if one of my hard drive fails, as a student user on a budget, I already have a problem; having a RAID only slightly amplifies the problem, in the sense of me having to spend some extra time recovering, but not that much.

So, personally, I'm getting, as we speak, two 30GB Maxtors on the abit's kt7-raid mobo, to be set up on RAID 0. We'll see how it works, but there should be significant performance improvement over the single drive.

btw, the previous post is right, if you read pcguide's story on RAIDs, you'll know everything (almost you need to know

 

[bastioned]

If iu want my opinion ´bout RAID systems, I´ve had the best experiences with this setup:

2 identical drives, same size. Ie , two 9 GB.
1 drive of double the size, that is 18 GB.

Arrange the smaller drives in this way:
- Configure them to use striping, RAID 0.
- Make the other drive ( 18 GB ) to be the mirror of the Stripe array , RAID 1.

This way iu have fastest access to 18 GB (9+9) and iu have fault-tolerance due to the 18 GB mirror.

Cool, isn´t it?

Bastion - Zero Tolerance

 

[Guest]

Um, technically wouldn't that be just as good as a single 18 gb harddrive (or two 18 gb hardrives)? From what I understand, you write 2 blocks of data. 1 goes to 9gb and 18, and the other goes to the other 9gb and the 18... In the end, the 18 is slowing down the entire process because the other drives finish in half the time, but still can't write ahead. Correct?

 

[smn198]

Yep. You're right, but if you have a large buffer on the raid card you may not run into this problem apart from writing large ammounts of data.

 

[smn198]

Does can a mirroing array be set up to reduce the seek time of the array? If two drives 1/2 a revolution out of sink, then the effective seek time would be halved. For writing, just add a buffer of about the ammount of data that the disk which is behind, can write in half a revolution.

Also, when creating a stripe array, does having a larger stripe block size increase performance in the same way that a larger cluster size does on a single disk?

 

[Guest]

Well, I appreciate all the information you guys gave. I think I will try Bastioned's suggestion. Anyone else think that's a good idea? Anyways, I'm looking at MSI's 694D Pro-AR motherboard which has the Promise RAID onboard. Wish me luck and let me know of any detailed setup that I should know or any experiences with this mobo. I appreciate the feedback.

 

[silverpig]

Actually, I don't think the hard drives have to be identical for a RAID 0 setup. It's just that if you try striping a 30 gig 7200 rpm ata 100 drive with a 15 gig 5400 rpm ata 66 drive, your RAID setup would perform the same as a 15 gig 5400 rpm RAID setup. ie, your setup would double the performance of the slowest of the two specs.