[ovirt-users] Recommended setup for a FC based storage domain

[combuster at archlinux.us]

Hi,

I have a 4 node cluster setup and my storage options right now are a FC based 
storage, one partition per node on a local drive (~200GB each) and a NFS based 
NAS device. I want to setup export and ISO domain on the NAS and there are no 
issues or questions regarding those two. I wasn't aware of any other options 
at the time for utilizing a local storage (since this is a shared based 
datacenter) so I exported a directory from each partition via NFS and it 
works. But I am little in the dark with the following:

1. Are there any advantages for switching from NFS based local storage to a 
Gluster based domain with blocks for each partition. I guess it can be only 
performance wise but maybe I'm wrong. If there are advantages, are there any 
tips regarding xfs mount options etc ?

2. I've created a volume on the FC based storage and exported it to all of the 
nodes in the cluster on the storage itself. I've configured multipathing 
correctly and added an alias for the wwid of the LUN so I can distinct this 
one and any other future volumes more easily. At first I created a partition 
on it but since oVirt saw only the whole LUN as raw device I erased it before 
adding it as the FC master storage domain. I've imported a few VM's and point 
them to the FC storage domain. This setup works, but:

- All of the nodes see a device with the alias for the wwid of the volume, but 
only the node wich is currently the SPM for the cluster can see logical 
volumes inside. Also when I setup the high availability for VM's residing on 
the FC storage and select to start on any node on the cluster, they always 
start on the SPM. Can multiple nodes run different VM's on the same FC storage 
at the same time (logical thing would be that they can, but I wanted to be 
sure first). I am not familiar with the logic oVirt utilizes that locks the 
vm's logical volume to prevent corruption.

- Fdisk shows that logical volumes on the LUN of the FC volume are missaligned 
(partition doesn't end on cylindar boundary), so I wonder if this is becuase I 
imported the VM's with disks that were created on local storage before and 
that any _new_ VM's with disks on the fc storage would be propperly aligned.

This is a new setup with oVirt 3.4 (did an export of all the VM's on 3.3 and 
after a fresh installation of the 3.4 imported them back again). I have room 
to experiment a little with 2 of the 4 nodes because currently they are free 
from running any VM's, but I have limited room for anything else that would 
cause an unplanned downtime for four virtual machines running on the other two 
nodes on the cluster (currently highly available and their drives are on the 
FC storage domain). All in all I have 12 VM's running and I'm asking on the 
list for advice and guidance before I make any changes.

Just trying to find as much info regarding all of this as possible before 
acting upon.

Thank you in advance,

Ivan