System information

Change the Path Selection Policy
Generally, you do not have to change the default multipathing settings your host uses for a specific storage
device. However, if you want to make any changes, you can use the Manage Paths dialog box to modify a path
selection policy and specify the preferred path for the Fixed policy.
Procedure
1 Open the Manage Paths dialog box either from the Datastores or Devices view.
2 Select a path selection policy.
By default, VMware supports the following path selection policies. If you have a third-party PSP installed
on your host, its policy also appears on the list.
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Fixed (VMware)
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Most Recently Used (VMware)
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Round Robin (VMware)
3 For the fixed policy, specify the preferred path by right-clicking the path you want to assign as the
preferred path, and selecting Preferred.
4 Click OK to save your settings and exit the dialog box.
Disable Paths
You can temporarily disable paths for maintenance or other reasons. You can do so using the vSphere Client.
Procedure
1 Open the Manage Paths dialog box either from the Datastores or Devices view.
2 In the Paths panel, right-click the path to disable, and select Disable.
3 Click OK to save your settings and exit the dialog box.
You can also disable a path from the adapter’s Paths view by right-clicking the path in the list and selecting
Disable.
Path Management and Manual, or Static, Load Balancing
Balancing loads among available paths improves performance. With both active/active and active/passive
storage arrays, you can set up your host to use different paths to different LUNs so that your adapters are being
used evenly.
If a path fails, the surviving paths carry all the traffic. Path failover might take a minute or more, because the
SAN might converge with a new topology to try to restore service. This delay is necessary to allow the SAN
to stabilize its configuration after topology changes.
With active/active storage arrays, you can configure your ESX/ESXi host to load balance traffic across multiple
adapters by assigning preferred paths to your LUNs. Path policy must be set to Fixed.
The following example demonstrates how manual load balancing is performed with an active/active array.
Assume the following setup, shown in Figure 6-1.
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Active/Active SPs
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An ESX/ESXi system
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Four Fibre Channel HBAs in each server
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Director class software
Chapter 6 Managing ESX/ESXi Systems That Use SAN Storage
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