Raid 5 on array w/14 drives=? usable drives 2

[ssoulages]

I am weighing the difference between running raid 5 on a Dell PowerVault array with 14 14GB drives, and running it without raid. I need to know how much storage space I will lose if I configure it with Raid 5.

Thanks!

 

[speedracercjr]

With RAID 5 you have to have one "hot" drive. So you will only lose 1 drive. The rest is usable storage.

 

[rrsub]

For RAID 5, the storage is the sum of the drives minus one.

If you really want to be anal about redundancy and have the proper Raid card, you could take the 14 drives, mirror each pair giving you 7 drives then Raid5 those giving you 6 mirrored, striped drives.

 

[ssoulages]

Thanks! Disk Space is at a premium, but if we can have the redudancy of Raid 5 by only losing one drive, we'll do it.

Thanks!

 

[OUCATS]

I thought overhead was about 30% per drive. Can you provide any documentation on the "sum of the drives minus one"?

 

[doomhamur]

Raid 5 takes however many disks you have and separates each disk into stripes. in a 14 disk raid 5 set each disk has 14 stripes. one stripe on each disk is used for parity checking. Thus you look the storage capacity of 1 disk ( N -1) for each array. Doomhamur
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