I have a kvm virtual host running on what will become CentOS 6 with 12GB of memory and a Quad Xeon  X5560 2.8Ghz .  The store for virtual machines will be a software raid 6 array of 6 disks with an LVM layered on top.  I'm not initially planning any major overcommitment of resources, though there could be a need for some overcommitment with a light workload on the guests.

 In recent years people seem to configure a wide range of different swap allocations.  I was thinking initially to spread swap across seperate non-raid partitions on 4 of these disks, but the downside of that is if I put 2gb on each disk, then I can only swap processes that will fit in 2gb swap space.  Also, if one of the disks fails, I have to reboot if anything was swapped to that drive.

My questions are as follows:

1. What experience are others having with putting swap space on raid partitions?  I was thinking about maybe swapping on a raid10 device, otherwise an LVM spanning multiple drives.
2. In practice, what kinds of swap allocation are people finding useful for a kvm virtual host of this size?
   

I definitely don't want a system that is so overcommited that performance is impacted, but if some overcommitment is reasonable for VM's that have light workload, then I consider that.  I can increase system resources when that becomes necessary.

Nataraj