VMware Virtual SAN Cookbook

Per object quorum in VSAN

Quorum is achieved by the addition of one or more zero-length witness components for each object. As quorum is defined as >50 percent availability, there must be greater availability than the components strictly required to provision each mirror (for example, a simple mirror with no striping will result in two data components; as ½ is exactly 50 percent, the >50 percent quorum rule cannot be maintained with data components alone). The voting difference in a per-object quorum is made up by witness components. Witnesses are pure metadata, with no production IO being serviced. As such, they consume no space on-disk and are comparatively cheap in terms of overhead. VSAN will create as many witnesses as necessary to ensure ...