FailOver Clustering (Windows):

Disk Witness & File Sharing Witness:
 

Why Disk-witness is better than File-Share Witness ?

Disk-Witness is preffered over File-Share Witness because Disk-Witness solves partition-in-time & File-Share Witness prevents partition-in-time Occuring

 

Difference between Disk-Witness & File-Share Witnes:

Disk-Witness	File-Share-Witness
Not used in Multi-Site Clustered	Used in Multi-Site Clusters because there wouldn't be shared storage between the two sites
Should be used where shared storage is available.	File-share witness should be placed in a third site to provide protection from a site failure.
Disk-Witness solves partition-in-time	File-Share Witness prevents partition-in-time Occuring

File Sharing Witness: 

File Sharing-Witness doesn't Contain replica of cluster configuration. 

It contains only Information that previous running node has most recent replica which have turned-off just now. So, To start cluster with other second node the previous node should be turned on or Node 1 can only be turned off when second node is started and running.

Contents Under File Sharing Witness:

Folder named with GUID of Cluster. 

In that folder, two files are created:

VerifyshareWriteAccess.txt

Witness.log