6.5.1

Table Of Contents
n
You cannot use multipathing software inside a virtual machine to perform I/O load balancing to a
single physical LUN. However, when your Microsoft Windows virtual machine uses dynamic disks,
this restriction does not apply. For information about configuring dynamic disks, see Set Up Dynamic
Disk Mirroring.
Setting LUN Allocations
This topic provides general information about how to allocate LUNs when your ESXi works with SAN.
When you set LUN allocations, be aware of the following points:
Storage provisioning To ensure that the ESXi system recognizes the LUNs at startup time,
provision all LUNs to the appropriate HBAs before you connect the SAN to
the ESXi system.
Provision all LUNs to all ESXi HBAs at the same time. HBA failover works
only if all HBAs see the same LUNs.
For LUNs that are shared among multiple hosts, make sure that LUN IDs
are consistent across all hosts.
vMotion and VMware
DRS
When you use vCenter Server and vMotion or DRS, make sure that the
LUNs for the virtual machines are provisioned to all ESXi hosts. This action
provides the most ability to move virtual machines.
Active-active compared
to active-passive arrays
When you use vMotion or DRS with an active-passive SAN storage device,
make sure that all ESXi systems have consistent paths to all storage
processors. Not doing so can cause path thrashing when a vMotion
migration occurs.
For active-passive storage arrays not listed in Storage/SAN Compatibility,
VMware does not support storage port failover. In those cases, you must
connect the server to the active port on the storage array. This configuration
ensures that the LUNs are presented to the ESXi host.
Setting Fibre Channel HBAs
Typically, FC HBAs that you use on your ESXi host work correctly with the default configuration settings.
You should follow the configuration guidelines provided by your storage array vendor. During FC HBA
setup, consider the following issues.
n
Do not mix FC HBAs from different vendors in a single host. Having different models of the same
HBA is supported, but a single LUN cannot be accessed through two different HBA types, only
through the same type.
n
Ensure that the firmware level on each HBA is the same.
n
Set the timeout value for detecting a failover. To ensure optimal performance, do not change the
default value.
vSphere Storage
VMware, Inc. 42