[CentOS-virt] RAID: by host or within KVM?

Fri Aug 10 14:39:18 UTC 2012
Kanwar Ranbir Sandhu <m3freak at thesandhufamily.ca>

Hi Virtualizers, 

I just setup a CentOS 6 box (at home) to run as a KVM host. It's replacing
an absolutely ancient CentOS 5 server that's running Xen. I have one OS
drive, and two drives in RAID 1 with LVM on top which is being used as the
KVM storage pool. 

I created a KVM that will run OpenMediaVault (OMV). OMV requires an OS
drive (which is really a LVM), and a separate drive(s) to put all the
on. This is where I'm a little unsure on how to proceed. I think I have

1. Let the KVM host manage the drives (i.e. RAID with LVM on top) and just
assign the single volume to OMV. OMV will see it as one HD.
2. Assign the individual drives to the OMV KVM, and let OMV manage the
creation, management, etc. 

I'm not sure which one will perform better. My hunch is if the RAID
management is left at the host level, I'll see better overall performance.
Performance isn't exactly my number one goal here, but I don't want to
it completely either by going the wrong way. 

On the other hand, if I let OMV do the RAID management for the media
storage disks, I'll gain future flexibility because it'll be much easier
move OMV to bare metal. 

Which way should I go? What would you guys do? 


Kanwar Ranbir Sandhu