RAID 5 and different disk sizes.

[phibit]

Hello! This is the situation: I have 3 hard drives, 2x 500GB and 1 x 200GB, and I want to set them up in some kind of RAID array (for performance boost).

Ideally, I would have 3x500 GB and I could just set up a nice 1TB hardware RAID 5... But alas, that isn't the case. I'm too scared to do a stripe RAID with both my 500GB, and I want to make use of the storage so I don't want to just mirror them...

So my question is: since it's possible to set up RAID 5 with these drives (with 200GB being the lowest common denominator), i could technically have:

1. 500 GB Drive: 200GB for raid 5, 300 GB unallocated
2. 500 GB Drive: 200GB for raid 5, 300 GB unallocated
3. 200 GB Drive: 200GB for raid 5, ~ 0 GB unallocated

My question is, what happens to the extra 600GB of unallocated space? I know this might sound like a dumb question, but I've never actually implemented a RAID config before. I have a feeling that the 600GB will be usable as two 300GB partitions, but I'm not 100% and would like confirmation or correction.

Also, if anybody can suggest a smart way to configure these 3 drives, so I can maximize performance, I would very much appreciate it!

Thanks!

 

[wte]

just use raid 0

 

[phibit]

Okay, but with RAID 0 I'm a but concerned about the consequence of failure... I'd like some redundancy?

 

[carver_g]

To answer your question, the unallocated space will not be usable. That's just how it is with RAID 5.

 

[phibit]

Ah, that's unfortunate, but good to know all the same...

So I guess RAID 0 is the best choice... I'm a bit reluctant to stripe my drives, as I'm scared of data loss. Does anybody have some experience with desktop RAID and how reliable it is (maybe some MTBF stats?).

Thanks

 

[Ignatowski]

raid 0 ( striping) suffers the same issue
jbod ( spanning) does not

personally i'd raid 0 the 500 gigs and just hook the other drive up for temp/swap space. isolating io across separate drives will often get you better performance than a raid stripe unless your only interested in total throughput.

as for reliablity its really a matter of the drives. ive had drives die after a week and others last 10 years. hard to give mtbf stats if you turn your pc off every night and only use it a couple hours a day then it should last forever. if you pound on the disks 24x7 with uncompressed video or sql then the drives are going to die quicker.

 

[Siggy19]

Use the 200GB drive for your OS, programs and page file and then RAID 1 (mirror) the two 500GB drives for your data.

You end up with 700GB of useable space with a fair amount of security.