I’ve been asked by a few customers about the location of the VMware ESX\ESXi LUN masking feature and how the LUN masking is done at the VMware ESX\ESXi level in version 4.
In VMware ESX 3.0/3.5 the settings for LUN masking were available in the UI via the Advance Software settings under Disk -> Disk.MaskLUNs as shown in screenshot below.

VMware ESX\ESXi 3.x Disk.MaxLUNs Settings

Well, here is the reason why you can’t find the Disk.MaskLUNs in the UI of ESX\ESXi 4. The component is no longer accessible under the ESX\ESXi’s 4 UI. The chance is implemented as a result of the re-architecture of the storage stack. The VMware Pluggable Storage Architecture (PSA)  is completely new. Old code and features were left behind in order to provide better, faster, and more reliable options and features. The Disk.MaskLUNs access via the UI was one of those left behind.

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