ESX Configuration Guide

The claim rules are numbered. For each physical path, the host runs through the claim rules starting with the lowest number first. The attributes of the physical path are compared to the path specification in the claim rule. If there is a match, the host assigns the MPP specified in the claim rule to manage the physical path. This continues until all physical paths are claimed by corresponding MPPs, either third-party multipathing plugins or the native multipathing plug-in (NMP).

For general information on multipathing plug-ins, see “Managing Multiple Paths,” on page 117.

For the paths managed by the NMP module, a second set of claim rules is applied. These rules determine which Storage Array Type Plug-In (SATP) should be used to manage the paths for a specific array type, and which Path Selection Plug-In (PSP) is to be used for each storage device. For example, for a storage device that belongs to the EMC CLARiiON CX storage family and is not configured as ALUA device, the default SATP is VMW_SATP_CX and the default PSP is Most Recently Used.

Use the vSphere Client to view which SATP and PSP the host is using for a specific storage device and the status of all available paths for this storage device. If needed, you can change the default VMware PSP using the vSphere Client. To change the default SATP, you need to modify claim rules using the vSphere CLI.

For detailed descriptions of the commands available to manage PSA, see the vSphere Command-Line Interface Installation and Scripting Guide and the vSphere Command-Line Interface Reference.

Viewing the Paths Information

Use the vSphere Client to determine which SATP and PSP the ESX host uses for a specific storage device and the status of all available paths for this storage device. You can access the path information from both, the Datastores and Devices views. For datastores, you review the paths that connect to the device the datastore is deployed on.

The path information includes the SATP assigned to manage the device, the path selection policy (PSP), and a list of paths with their physical characteristics, such as an adapter and target each path uses, and the status of each path. The following path status information can appear:

Active	Paths available for issuing I/O to a LUN. A single or multiple working paths
	currently used for transferring data are marked as Active (I/O).
	NOTE For hosts that run ESX 3.5 or earlier, the term active means the only path
	that the host is using to issue I/O to a LUN.
Standby	The path is operational and can be used for I/O if active paths fail.
Disabled	The path is disabled and no data can be transferred.
Dead	The software cannot connect to the disk through this path.

If you are using the Fixedpath policy, you can see which path is the preferred path. The preferred path is marked with an asterisk (*) in the Preferred column.

View Datastore Paths

Use the vSphere Client to review the paths that connect to storage devices the datastores are deployed on.

Procedure

1 Log in to the vSphere Client and select a server from the inventory panel. 2 Click the Configuration tab and click Storage in the Hardware panel.

3Click Datastores under View.

122	VMware, Inc.