Hi,
With the new SAN here is what you would have in the Infra:
DC B- ESXi5.5 + SAN5.5 (new san)
DC A- ESXi4.x + SAN4.x (old san)
Assumption:
SAN5.5 is also compatible with ESXi4.x
SAN4.x will be decommissioned after the migration is complete because its not supported on ESXi 5.5. This means that all the VMs have to be migrated to the new san for this activity to complete.
All the VMs are currently provisioned on SAN4.x and since it does not support 5.5 yet, IMO here are the options that you have:
Upgrade one of the ESXi hosts to 5.5
Present SAN5.5 LUNs to the upgraded ESXi 5.5 host
Storage vMotion the VMs from SAN4.x o SAN5.5
Once all VMs are migrated to the new SAN, the old storage can be decommissioned.
Alternatively if both Storage Arrays are from the same vendor, you can use the vendor provided tools to do a block level copy from SAN4.x to SAN5.5. In the past for the data migration engagements on VMware I have used Storage vMotion and I must say that there has been a great improvement from ESX3.5 to 5.5. However this also depends on other factors for example, some times doing array level copy and then resignature the VMFS LUNs is easier.
-Arun
Twitter: https://twitter.com/arunpande
Blog: http://highoncloud.blogspot.in/
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