RAID 1, Matrix RAID

[Fragmire]

I'm thinking about moving my system onto a RAID-1 configuration so I don't lose valuable data (I do routine backup, but only when I have time, which isn't very often). Since I've never dealt w/ RAID before, I'd appreciate any help in answering some of the questions I have:

1. For most RAID chips, do I have to use an entire drive to create a RAID partition? For example, I have two 160GB HD, do I have to create one RAID-1 partition of 160GB, or can I create, say, one RAID-1 partition of 120GB and leaving the rest as JBOD?

2. Is the Matrix RAID an Intel-only feature on ICH?R? Is there any other chip out there that supports this?

Ideally, I'd like to have the features of Matrix RAID, but I would rather not upgrade my entire motherboard+CPU+RAM+everything just to get it.

Thanks.

 

[Seekermeister]

I don't know anything about Matrix raid, but both drives will be entirely raid, but you can divide it into partitions.

 

[gramboh]

Yes Matrix RAID solves this problem (dedicate certain portion of drive to different RAID level) allowing you to have RAID 0+1 on a 2 disk array.

Apparently performance is very good on small arrays (e.g. 2 disk) there is a review if you google (I can't remember URL).

I believe it is Intel only, not sure which chipsets.

 

[Fragmire]

So it seems like that I won't be going with Matrix RAID anytime soon since 1) I don't want to upgrade until at least after Vista comes out and Intel slashes CPU prices next year, and 2) I have an mATX system, and there doesn't seem to be any good motherboard with ICH8R.

On a related note, I haven't been able to successfully verify that RAID-1 increases performance. The article on Wikipedia states that since the controller can dispatch read requests between the drives, it effectively increases read performance. Do all RAID-1 controllers support this level of intelligence, or is it only on the high-end?

 

[Fragmire]

Anyone knows if all RAID-1 controllers support the dispatching of read requests amongst the drives in the array, or is this a feature only on the high-end?

 

[Matthias99]

Originally posted by: Fragmire
Anyone knows if all RAID-1 controllers support the dispatching of read requests amongst the drives in the array, or is this a feature only on the high-end?

I think you mean "intelligently dispatching the requests to minimize seek time", since I don't think I've ever seen a RAID1 that didn't at least split the reads between drives.

Depends on the controller. I would think that even the cheaper ones probably support it nowadays, but you really can't say unless the documentation tells you or someone has tested it. In practice, most 'normal' usage patterns don't really involve the sort of deeply queued reads that would benefit from this kind of dispatching. Something like a database server would probably see a benefit, but not most desktop tasks.

 

[Madwand1]

Originally posted by: Matthias99
I don't think I've ever seen a RAID1 that didn't at least split the reads between drives.

Good info otherwise, but I don't think you've tried enough cheap RAID 1 implementations.

I haven't tried many myself, but am hitting 0 for 2 right now -- nForce3 and VIA VT8237 do not improve read performance beyond a single drive in RAID 1. So they either don't split reads, or do it in a way that doesn't help simple workloads at least.