[CentOS] Advice on partitioning a Dell MD1200 disk array

Hi,

I've just got possession of a Dell PE R720 with 2 MD1200 disk 
enclosures.

Both MD1200 are fully populated with 12 x 3 TB disks

The system will basically be a student file-server running CentOS 6.x  
serving various size files from small c programs to multi gigabyte 
audio and video files over GB ethernet.

The first MD1200 will be configured as the NFS disk. The requirements 
are for 6 fixed equally sized partitions, one for each cohort of 
students. For this I was thinking of splitting the MD1200 into 2 RAID5 
arrays with a hot spare each. Then partitioning each into 3 ext4 
partitions.

The second MD1200 will be used to backup the first, using BackupPC and 
for other storage purposes.

As I won't know the storage requirements for the "backup partition" 
and they will probably change over time anyway. I was thinking of 
using LVM for it. So how to partition the MD1200 for LVM. I don't want 
to put all 12 disks in  a RAID5 and put a LVM volume on it. Can I 
split it into 2 RAID5 and have a LVM volume spanning both.

Any suggestions. 

Just remember I'm due to retire at the end of this month so this will 
be my last big job for the Dept. And due to financial constraints I 
will not be replaced. So I will be handing this machine over to a co-
worker who is basically a Windoze admin with only a basic knowledge of 
Linux so nothing too fancy.  ;-)

Thanks,

Tony


--

Tony Molloy

CTO, Dept. of Comp. Sci.
University of Limerick
Limerick.
Ireland