Cannot create a VMFS datastore using the Add Storage Wizard

Products

• VMware vSphere ESXi

Issue/Introduction

This article addresses an issue when creating a VMFS datastore on a Storageflex 3945N LSS array or other Storage array which supports 4096 byte block sizes.

Symptoms:

• A new LUN is presented to the ESX host.
• When using the Add Storage wizard to create a datastore, you see the error:
  
  Unable read partition information from this disk
  
  
• Using Fdisk on the LUN after the add wizard attempt shows that a partition table is not defined.
  
• Running the parted /dev/sdX command (the Linux device name attached to the LUN) generates this error:
  
  Device /dev/sbX has a logical sector size of 4096. Not all parts of GNU Parted Support this at the moment, and the working code is HIGHLY EXPERIMENTAL.

Environment

VMware ESXi 4.0.x Installable
VMware ESXi 4.1.x Installable
VMware ESX 4.1.x
VMware vSphere ESXi 6.0
VMware vSphere ESXi 5.5
VMware ESXi 4.0.x Embedded
VMware vSphere ESXi 5.1
VMware ESXi 3.5.x Embedded
VMware ESX Server 3.5.x
VMware ESXi 3.5.x Installable
VMware ESX 4.0.x
VMware ESXi 4.1.x Embedded
VMware vSphere ESXi 5.0

Cause

This issue occurs when LUN sector size exceeds 4k block sizes (4096 bytes). This is sometimes called as Advanced Format drives.

Resolution

The 3945N LSS array allows for a LUN sector size of 4096.

To resolve this issue, change the LUN sector size to 512.

Additional Information

There are limited cases in vSphere 5.5 where 4k/Advanced Format drives can be used as physical-mode RDM devices by virtual machines which support 4k block sizes.