Pre-Order Your Advanced VMware Cloud Foundation 9.0 Storage 3V0-23.25

A vSAN Stretched Cluster requires both compute placement control and storage placement control. To place virtual machines in the appropriate site, the administrator must create VM/Host groups for the two sites. This allows DRS to understand which hosts belong to the preferred site and which hosts belong to the secondary site, and it allows VM-to-host affinity rules to be created for initial and ongoing placement. The administrator must also create a storage policy for each site or site placement requirement. vSAN stretched-cluster storage policies control site disaster tolerance and data locality, including whether objects are mirrored across sites or kept on the preferred or secondary site. VM folders do not control runtime or storage placement. A VM/Host group “across the two sites” is not correct because site separation must be explicitly modeled. Simply placing a VM into a DRS group is not enough unless the site groups and policies already exist. Reference topics: vSAN Stretched Cluster Design Considerations, DRS Host Groups, VM Groups, VM-Host Rules, vSAN Storage Policy Site Locality.

In vSAN ESA, the observed three disk stripes are expected behavior for objects using RAID-1, even when the storage policy shows “Number of disk stripes per object = 1.” The vSAN policy rule defines the minimum number of capacity devices across which each replica of an object is striped, and the default value is 1. However, VMware documentation explicitly notes that objects in a vSAN ESA cluster with RAID-0 or RAID-1 configuration have 3 disk stripes, even if the default storage policy defines only 1 disk stripe. Therefore, the three stripes are not caused by site mirroring itself, nor by the VM having three objects. Site mirroring controls placement across the preferred and secondary sites in a stretched cluster, while Failures to tolerate with RAID-1 controls local host/device protection. The behavior is also not evidence that a VM-level policy override exists. The datastore-level policy can still be applied correctly; ESA’s internal RAID-1 object layout uses three stripes as part of its optimized storage architecture. Reference topics: vSAN ESA Default Storage Policy Characteristics, Number of Disk Stripes per Object, RAID-1 Mirroring, vSAN Stretched Cluster Storage Policies.

VMware Live Site Recovery uses VM readiness signals to control recovery sequencing between priority groups. Recovery Priority is used to start and validate higher-priority workloads before lower-priority workloads continue, which is important for application dependency chains such as identity services, databases, middleware, and application servers. A VM being registered or powered on does not prove that the guest operating system is usable. Similarly, final replication completion only confirms storage synchronization, not guest readiness. VMware Tools heartbeat provides a guest-level indication that the operating system has started and is responsive. This makes it the correct mechanism for determining that a recovery priority step has completed and that the recovery plan can continue to the next priority group. The “successfully recovered” state is the result of the recovery workflow, not the signal used to progress between priority groups. Reference topics: VMware Live Site Recovery, Recovery Plans, Recovery Priority, VMware Tools Heartbeat, Application Recovery Sequencing.