Download Using VMware ESX Server

C H A P T E R 9 Storage and File Systems
Setting Your Multipathing Policy for a LUN
You can specify the default policy for the multipathing feature. There are two policies:
• fixed — ESX Server always uses the preferred path to the disk; if it cannot access
the disk through the preferred path, then it tries the alternate paths. Fixed is the
default policy for active/active storage devices.
Enter the following command to select the fixed policy for a disk, in this example,
vmhba0:0:0.
# vmkmultipath -s vmhba0:0:0 -p fixed
• mru — ESX Server uses the most recent path to the disk until this path becomes
unavailable. That is, ESX Server does not automatically revert back to the
preferred path. Most recent path (mru) is the default policy for active/passive
storage devices.
Note: Use the MRU path policy for disks on active/passive storage devices.
Enter the following command to select the mru policy for a disk, in this example,
vmhba0:0:0.
# vmkmultipath -s vmhba0:0:0 -p mru
You can select a different policy for each disk.
Note: Use the MRU policy for disks on active/passive storage devices. Using the fixed
policy may cause path thrashing and significantly reduced performance.
Specifying Paths
You can use the vmkmultipath command to disable and enable paths, set the
active path, and set the preferred path, as illustrated in the following examples. You
configure paths by setting path modes with the -s option.
Enabling a Path
Use the -e option to enable paths with vmkmultipath. In this example, you are
enabling the path from controller vmhba1:0:1 to disk vmhba0:0:1.
# vmkmultipath -s vmhba0:0:1 -e vmhba1:0:1
Disabling a Path
Use the -d option to disable paths with vmkmultipath. In this example, you are
disabling the path from controller vmhba1:0:1 to disk vmhba0:0:1.
# vmkmultipath -s vmhba0:0:1 -d vmhba1:0:1
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