System information

Requirements and Installation 3
When you use ESX/ESXi systems with SAN storage, specific hardware and system requirements exist.
This chapter includes the following topics:
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“General ESX/ESXi SAN Requirements,” on page 29
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“ESX Boot from SAN Requirements,” on page 31
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“Installation and Setup Steps,” on page 31
General ESX/ESXi SAN Requirements
In preparation for configuring your SAN and setting up your ESX/ESXi system to use SAN storage, review the
requirements and recommendations.
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Make sure that the SAN storage hardware and firmware combinations you use are supported in
conjunction with ESX/ESXi systems.
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Configure your system to have only one VMFS volume per LUN. With VMFS-3, you do not have to set
accessibility.
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Unless you are using diskless servers, do not set up the diagnostic partition on a SAN LUN.
In the case of diskless servers that boot from a SAN, a shared diagnostic partition is appropriate.
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VMware recommends that you use RDMs for access to any raw disk from an ESX Server 2.5 or later
machine.
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For multipathing to work properly, each LUN must present the same LUN ID number to all ESX/ESXi
hosts.
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Make sure the driver you use in the guest operating system specifies a large enough queue. You can set
the queue depth for the physical HBA during system setup.
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On virtual machines running Microsoft Windows, increase the value of the SCSI TimeoutValue parameter
to 60. This increase allows Windows to better tolerate delayed I/O resulting from path failover.
Restrictions for ESX/ESXi with a SAN
This topic lists restrictions that exist when you use ESX/ESXi with a SAN.
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ESX/ESXi does not support FC 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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You cannot use virtual machine logical-volume manager software to mirror virtual disks. Dynamic disks
on a Microsoft Windows virtual machine are an exception, but require special configuration.
VMware, Inc.
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