Raid 10 With different disk sizes

LRL455 used Ask the Experts™
We currently have a server with four 1.5TB drives configured as raid10, also in that server we have four 2.0TB drives configured with raid10. I'd like to leverage the performance of striping across half of these disks and mirroring the other. From what I can find about raid 10, it should theoretically work. I dont cherish the idea of actually trying this without some idea. Does anyone know if this will work with RAID10 and has anyone ever done this?
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It will work but you will lose the additional .5TB on the 2TB drives. Do the drives at least have the same cache and have the same RPM?
If you combine the disks you will loose the top .5 TB of the 2TB drives.   What exactly are you trying to do, i'm not sure by your description.  Are you trying to make a big RAID10 set?


I'm just trying to make a big raid 10 set, to take advantage of the additional performance of 4 disks being striped vs 2.

4 of the disks are Seagate SATA 1.5TB with 32MB cache 7200RPM, the others are WD 2.0TB with 32MB cache 7200RPM.

Because of RAID10 mirroiring and then striping the mirrors I had the hope that it would work like this.

|~~~~~~Striped~~~~~~~~~| for a total of 7.0TB
1.5TB  1.5TB  2.0TB  2.0TB
1.5TB  1.5TB  2.0TB  2.0TB Mirrors
Nope you will get 1.5TB x 4 or 6TB.  On most controllers you should be able to use the additional space in the 4 disks in a seperate array but not in the inital array.


I understand now why my scenario wouldnt work. I guess I was thinking about it in spanned terms instead of striped.

Striping is in blocks, typically 64KB. 64KB on disk A, 64KB on disk B another 64KB on disk A and so on till all the data is written. A 1.5TB drive will take 25,165,824 blocks of 64KB where as 2.0TB drive will take 33,554,432 blocks of 64KB.

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