Setup new SAN. Create LUNS on SAN equal to or greater than existing Datastore size(s). Present LUNS to ESX Hosts and format as VMFS. Then svmotion VMs to new Datstores. Once all VMs are over and you are satisfied everything is working remove old datastores and chuck you Clariion.
to add to lightbulb's answer, i would perform svmotion during low I/O or non-business hours, because of performance issues. we've seen high cpu usage on the VMs during and 2hours after the migration.
If you don't like using the console for Storage vMotion here is a nice little plugin that you can install into your vCenter:
http://vip-svmotion.wiki.sourceforge.net/
I have had no problems with it so far and it has saved me a lot of support calls 😛
My virtual machines are in SAN.
Please clarify me on this , Svmotion will move only the vmdk disk ,so i have to create a new custom VM with the migrated vmdk disk
Both vmx and vmdk files will be migrated to new LUN using svmotion. The VMs will be on the same host but the files that makeup the VM will be moved to the new datastore.