I guess I should come at it from the other side: If you have 1 iscsi target box and it goes down, you're dead in the water.
If you have 2 iscsi target boxes that replicate and one dies, you are OK but you then have to have a 2:1 total storage to usable ratio (excluding expensive shared disks). If you have 2 tiers where you have n cheap back-end iSCSI targets that have the physical disks in them and present them to 2 clustered virtual iSCSI target servers (assuming this can be done with disks over iSCSI) that are presenting the iSCSI targets to the VMware hosts, then any one server could go down but everything would keep running. It would create a virtual clustered pair that is basically doing RAID over the network (iSCSI). Since you already have the VMware hosts, the 2 virtual ones are "free". None of the back-end servers would need redundant components because any one can fail, so you should be able to build them with inexpensive parts. This would also allow you to add/replace storage easily (I hope). Perhaps you'd have to RAIDZ the backend disks together and then present them to the front-end which would RAIDZ all the back-ends together. For example, if you had 5 backend boxes with 8 drives each you'd have a 10:7 ratio. I'm sure the RAID combinations could be played with to get the balance of redundancy and capacity that you need. I don't know what kind of performance hit you would take doing that over iSCSI but I thought it might work as long as you have gigabit speeds. Or I could be completely off my rocker. :) Am I? -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
