Understanding the message "The entire contents of this disk are about to be erased and replaced with the specified configuration, are you sure?" when increasing disk capacity.

Products

• VMware vSphere ESXi

Issue/Introduction

The following message shows in the end of the process of increasing the size of an existing datastore by adding an LUN extension to it (choosing the option "Add an extent to existing VMFS datastore").

"The entire contents of this disk are about to be erased and replaced with the specified configuration, are you sure?"

Cause

This message is a warning indicating that the contents of the new LUN added to be used in the extension will be erased during the formatting of the volume to compose the existing VMFS disk.

The message is not related to the existing data that is stored in the current datastore that is being increased.

Resolution

The data that will be erased is the data that is stored in that new LUN, not the data of the existing datastore that is being increased.

It's safe to click yes when:

• The LUN is a newly created LUN in the storage and published to the host, then no existing data will be lost.
• The LUN has no important data that can be lost.

 

It's NOT safe to click yes when:

• The new LUN is an existing VMFS volume that is being reused 
• The LUN was being used by any other reason and has important data on it.
• Any similar message shows on other conditions of increasing a datastore, for instance when increasing a datastore using the option "Expand an existing VMFS datastore extent"