6.0.1

Table Of Contents
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“Conguring CHAP Parameters for iSCSI Adapters,” on page 98
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“Conguring Advanced Parameters for iSCSI,” on page 102
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“iSCSI Session Management,” on page 103
ESXi iSCSI SAN Requirements
You must meet several requirements for your ESXi host to work properly with a SAN.
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Verify that your SAN storage hardware and rmware combinations are supported in conjunction with
ESXi systems. For an up-to-date list, see VMware Compatibility Guide.
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Congure your system to have only one VMFS datastore for each LUN.
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Unless you are using diskless servers, set up a diagnostic partition on a local storage. If you have
diskless servers that boot from iSCSI SAN, see “General Boot from iSCSI SAN Recommendations,” on
page 107 for information about diagnostic partitions with iSCSI.
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Use RDMs for access to any raw disk. For information, see Chapter 18, “Raw Device Mapping,” on
page 205.
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Set the SCSI controller driver in the guest operating system to a large enough queue. For information on
changing queue depth for iSCSI adapters and virtual machines, see vSphere Troubleshooting.
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On virtual machines running Microsoft Windows, increase the value of the SCSI TimeoutValue
parameter to allow Windows to beer tolerate delayed I/O resulting from path failover. For
information, see “Set Timeout on Windows Guest OS,” on page 187.
ESXi iSCSI SAN Restrictions
A number of restrictions exist when you use ESXi with an iSCSI SAN.
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ESXi does not support iSCSI-connected tape devices.
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You cannot use virtual-machine multipathing software to perform I/O load balancing to a single
physical LUN.
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ESXi does not support multipathing when you combine independent hardware adapters with either
software or dependent hardware adapters.
Setting LUN Allocations for iSCSI
When preparing your ESXi system to use iSCSI SAN storage you need to set LUN allocations.
Note the following points:
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Storage Provisioning. To ensure that the host recognizes LUNs at startup time, congure all iSCSI
storage targets so that your host can access them and use them. Also, congure your host so that it can
discover all available iSCSI targets.
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vMotion and VMware DRS. When you use vCenter Server and vMotion or DRS, make sure that the
LUNs for the virtual machines are provisioned to all hosts. This conguration provides the greatest
freedom in moving virtual machines.
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Active-active versus active-passive arrays. When you use vMotion or DRS with an active-passive SAN
storage device, make sure that all hosts 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. You must connect the server to the active port on the storage system. This
conguration ensures that the LUNs are presented to the host.
vSphere Storage
70 VMware, Inc.