6.7

The rules fall into these categories:
Core Claim Rules These claim rules determine which multipathing module, the NMP, HPP, or
a third-party MPP, claims the specific device.
SATP Claim Rules Depending on the device type, these rules assign a particular SATP
submodule that provides vendor-specific multipathing management to the
device.
You can use the esxcli commands to add or change the core and SATP claim rules. Typically, you add
the claim rules to load a third-party MPP or to hide a LUN from your host. Changing claim rules might be
necessary when default settings for a specific device are not sufficient.
For more information about commands available to manage PSA claim rules, see the Getting Started with
vSphere Command-Line Interfaces.
For a list of storage arrays and corresponding SATPs and PSPs, see the Storage/SAN section of the
vSphere Compatibility Guide.
Multipathing Considerations
Specific considerations apply when you manage storage multipathing plug-ins and claim rules.
The following considerations help you with multipathing:
n
If no SATP is assigned to the device by the claim rules, the default SATP for iSCSI or FC devices is
VMW_SATP_DEFAULT_AA. The default PSP is VMW_PSP_FIXED.
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When the system searches the SATP rules to locate a SATP for a given device, it searches the driver
rules first. If there is no match, the vendor/model rules are searched, and finally the transport rules
are searched. If no match occurs, NMP selects a default SATP for the device.
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If VMW_SATP_ALUA is assigned to a specific storage device, but the device is not ALUA-aware, no
claim rule match occurs for this device. The device is claimed by the default SATP based on the
device's transport type.
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The default PSP for all devices claimed by VMW_SATP_ALUA is VMW_PSP_MRU. The
VMW_PSP_MRU selects an active/optimized path as reported by the VMW_SATP_ALUA, or an
active/unoptimized path if there is no active/optimized path. This path is used until a better path is
available (MRU). For example, if the VMW_PSP_MRU is currently using an active/unoptimized path
and an active/optimized path becomes available, the VMW_PSP_MRU will switch the current path to
the active/optimized one.
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While VMW_PSP_MRU is typically selected for ALUA arrays by default, certain ALUA storage arrays
need to use VMW_PSP_FIXED. To check whether your storage array requires VMW_PSP_FIXED,
see the VMware Compatibility Guide or contact your storage vendor. When using VMW_PSP_FIXED
with ALUA arrays, unless you explicitly specify a preferred path, the ESXi host selects the most
optimal working path and designates it as the default preferred path. If the host selected path
becomes unavailable, the host selects an alternative available path. However, if you explicitly
designate the preferred path, it will remain preferred no matter what its status is.
vSphere Storage
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