vSphere Storage - ESXi 5.1 - Documentation - VMware

vSphere Storage
Setting LUN Allocations
This topic provides general information about how to allocate LUNs when your ESXi works in conjunction
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.
vMotion and VMware
DRS
Active-active compared
to active-passive arrays
Setting Fibre Channel HBAs
VMware recommends that you 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 will be shared among multiple hosts, make sure that LUN IDs
are consistent across all hosts. For example, LUN 5 should be mapped to host
1, host 2, and host 3 as LUN 5.
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 provides the
most ability to move virtual machines.
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.
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.
n ESXi supports 16GB FC HBAs, but there is no support for full end-to-end 16GB connectivity from the host
to array. If you use 16GB FC HBAs running at 16GB, to get full bandwidth, create at lease two 8GB
connections from the switch to the storage array.
Installation and Setup Steps
This topic provides an overview of installation and setup steps that you need to follow when configuring your
SAN environment to work with ESXi.
Follow these steps to configure your ESXi SAN environment.
1 Design your SAN if it is not already configured. Most existing SANs require only minor modification to
work with ESXi.
40 VMware, Inc.