Best RAID for 15 x 2TB SAS disks

[Lanz]

This is for a CCTV server, which the data doesn't get backed up on, what what you choose and why? (or is there an Option 6?)
15 Disk Dell MD1000 Enclosure, attached to a Server with a 256MB Perc6E.
2TB 7.2K SAS/SATA = 1862GB
Option 1 (2 x Raid6 Arrays with 2 hot-spares)
Array1: 9310 GB
Array2: 7448 GB
Total: 16758 GB
Option 2 (2 x Raid6 Arrays with 1 global hot-spare)
Array1: 9310 GB
Array2: 9310 GB
Total: 18620 GB
Option 3 (1 x RAID50 Array with 2 hot-spares)
Total: 20482 GB
Option 4 (1 x RAID50 Array with 1 hot-spare)
Total: 22344 GB
Option 5 (1 x RAID6 Array with 1 hot-spare)
Total: 22344 GB

 

[Lanz]

There is no way to backup the data because of the CCTV software that is used, they design it that way to sell you a extra licenses . If we wanted a backup of the footage, each camera records to two locations - thats your backup.

If we backed up this data, then when you restore it, you just get a meaningless mess of files, you'd have to take a point in time snap of the OS/App and the DATA to get a proper, usable backup.

Your option 3 size is wrong.

If you knock the 2 hot spares off you've got 13 drives left. You obviously can't build a RAID50 with an odd number of drives, so you've got to drop down to 12. I think it should be 18620GB.

Ah thanks for spotting.

My manager, has opted for RAID6+2SP = 20TB... He said he prefered Raid6 over RAID50...