We've done 3) by creating a LUN on the SAN for each domU. Works well, and is nice to use on a SAN that has snapshot support. Rather than running iscsi (or aoe) in the guest, we open all LUNs on the dom0 and export each to its respective domU via xenblk.
On a SAN with a limited number of LUNs, we also did 2) but with CLVM on the dom0 hosts. That allowed each dom0 in the cluster to view each logical volume. Migrations are easy but as noted elsewhere, CLVM has no snapshot support. Has the advantage that logical volume labels are nice and descriptive.
Disk performance either way is limited by the SAN and network, and can be quite good. I've successfully virtualized database servers and other hosts with intensive I/O requirements.
-Jeff
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of VPS Lime
Sent: Thursday, November 11, 2010 10:29 PM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Opinion on best way to use network storage
I need the community's opinion on the best way to use my storage SAN to host xen images. The SAN itself is running iSCSI and NFS. My goal is to keep all my xen images on the SAN device, and to be able to easily move images from one host to another as needed while minimizing storage requirements and maximizing performance.
What I see are my options:
1) Export a directory through NFS. Create image files on the NFS mount and have each zen guest use the image off the NFS mount. This has the benefit of all images being visible to all hosts (on the NFS mount), but I'm not sure about the performance.
2) Create an image on the SAN server for each XEN host and export it to the XEN servers through iSCSI. The XEN server will see it as a VolumeGroup. Create Logical Volumes in the VolumeGroup for each XEN guest. Has the advantage of using LVM for the guest instead of an image file (which is rumored to be faster). Disadvantage is individual images are not easily moved to other hosts
3) Create a image on the SAN server for each XEN guest and export it through iSCSI. Attach XEN guests directly to the iSCSI image. Has the advantage of being portable to other hosts, maybe more efficient?
