User story: As an administrator, I want to attach a Cinder volume to multiple instances to support active/active or active/standby scenarios, and in order to deploy clustered database systems, such as MSSQL, Oracle, etc. Purpose of function: The ability to attach a volume to multiple hosts/servers simultaneously in both Cinder and Nova with read/write (RW) mode, to address the clustered application workloads use case that typically requires active/active or active/standby scenarios. In order to do this R/W there are a number of issues involved with respect to data corruption etc.
Updated content available on the Customer Portal: https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/16.1/html-single/instances_and_images_guide/index#attaching-a-volume-to-multiple-instances_instances