Dell PowerVault MD3260 Dell PowerVault MD Storage Array VMware vCenter Plug-in - Page 29

Double Failure

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Figure 22. Double Failure While this method works well in the case of hardware failure, MRU only maintains one active path for each HBA group. Therefore, if you have an ESX/ESXi host with four HBAs, only one HBA is active at a time. To achieve higher I/O throughput from the 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. 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 fibrechannel bandwidth between all HBA groups. When this method is used in the array, the Automatic host configuration utility cannot determine which HBAs are configured to each fabric zone. The user must verify that a single HBA is connected to both fabric zones for each HBA pair group. Dell MD Storage Array vCenter Plug-in | 29

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Dell MD Storage Array vCenter Plug-in
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Figure 22.
Double Failure
While this method works well in the case of hardware failure, MRU only maintains one active path for each
HBA group. Therefore, if you have an ESX/ESXi host with four HBAs, only one HBA is active at a time. To
achieve higher I/O throughput from the 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. 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 host
configuration utility cannot determine which HBAs are configured to each fabric zone. The user must verify
that a single HBA is connected to both fabric zones for each HBA pair group.