Dell PowerVault MD3000 - Manual (Page 26)

Dell MD Storage Array vCenter Plug-in | 26
Figure 22. Double Failure
This method works well to maintain the in-case of a hardware failure; however, MRU only maintains one
active path for each HBA group. Therefore, if you have an ESX host with four HBAs, only one HBA is active
at a time. To achieve higher I/O throughput from the ESX host to the storage array, it is recommended that you
group the HBAs in pairs and create virtual hosts for each pair of HBAs. This allows for a fully redundant
configuration but also allows for two of the HBAs to be active at the same time versus a single HBA. See
Figure 23 . From the storage array, the second pair of HBAs is defined as a separate host and virtual disks can
then be mapped directly to the new host or host group. This same methodology can be used to group additional
HBAs in the same manner. This does require additional management to balance the LUNs between the
hosts/host groups to fully use the fibre channel bandwidth between all HBA groups. When this method is used
in the array, the Automatic ESX host configuration utility cannot determine which HBAs are configured to
each zone in the and the user must verify that a single HBA is connected to both fabric zones for each HBA
pair group.