X4500 RAID Configuration for best performance for video storage

Question

Hello all:
Our company is working with a local university to deploy IP video security cameras. The university has an X4500 Thumper that they would like to use for the storage of the video archives. The video management software (VMS) will run on an Intel based server with Windows 2003 server as the OS and connect to the Thumper via iSCSI. The VMS manages the permissions, schedules and other features of the cameras and records all video on the local drives until the scheduled archive time. When the archive time occurs, the VMS transfers the video to the Thumper for long term storage. It is our understanding that when using iSCSI and Windows OS there is a 2TB limit for the storage space - so we will divide the pool into several 2TB segments.
The question is: Given this configuration, what RAID level (0, 1, Z or Z2) will provide the highest level of data protection without comprimising performance to a level that would be noticable? We are not writing the video directly to the Thumper, we are transferring it from the drives of the Windows server to the Thumper, and we need that transfer to be very fast - since the VMS stops recording during the archiving and restarts when complete, creating down time for the cameras.
Any advice would be appreciated.

Answer 1

I'd put as many disks as possible into a RAID 5 (striping) set. This will provide the highest level of performance, with the ability to sustain a single disk failure.
With striping, some data is written to all the disks in the stripe set. So, if you have 10 disks in the set, then instead of writing data to a single disk, which is slow, 1/10th of the data is written to each disk simultaneously, which is very fast. In effect, the more disks you write to, the faster the operation completes.