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11 Dell PS Series Arrays: Advanced Storage Features in VMware vSphere | TR1066
5 vStorage APIs for Storage Awareness for vSphere 5.x
With the release of vSphere 5.0, VMware added vStorage APIs for Storage Awareness (VASA) to its set of
APIs. VASA enables vCenter to communicate with the PS Series array, through the PS Series VASA Provider,
to discern the capabilities of each volume presented to the vSphere environment. This enables the vCenter
client to display pertinent information about a datastore, such as the ability of the underlying volume to
perform snapshot or replication data protection, the RAID type such as heterogeneous or homogeneous,
or the type of drives such as SSD. This enables vSphere administrators to be more aware of the storage
capabilities in the virtual environment and allows administrators to better match virtual machine storage
needs with the correct datastore. Without this feature, administrators must track this information manually.
This storage capability information is displayed in the Datastores and Datastore Clusters view, and also can
be viewed from the PS Series Datastore Manager plugin.
While the basic capability of VASA does not require a particular vSphere license, Enterprise Plus licensing is
required by two vSphere features that leverage this information from VASA: Profile-Driven Storage and
Storage Distributed Resource Scheduler. See Table 1 for more information on vSphere licensing
requirements.
5.1 Storage-Based Policy Management
Storage-Based Policy Management (formerly Profile-Driven Storage) uses VASA-provided information to
ensure that virtual machines reside on the appropriate datastores. An administrator can create various
storage profiles that reflect particular data-protection needs. When a virtual machine is created, the
administrator can select the storage profile that meets the requirements of the virtual machine, and place
the virtual machine on datastore that provides these capabilities. If the virtual machine is later migrated to
a datastore that does not meet the storage profile, or if the capabilities of the datastore change and no
longer meet the storage profile, the virtual machine will fail its storage profile compliance check. The
compliance status can be seen on the summary page for the individual virtual machine and on the VM
storage profile for all virtual machines assigned a storage profile. Storage-Based Policy Management
through the PS Series VASA Provider helps administrators quickly ensure that virtual machines are placed
on the right datastore and continue to reside on datastore that meet their needs.
5.2 Storage Distributed Resource Scheduler
Storage Distributed Resource Scheduler (Storage DRS) takes the VMware CPU and memory resource
management concepts and applies them to datastores. Like the traditional DRS capability of VMware,
Storage DRS groups datastores with similar performance characteristics into a datastore cluster. When a
virtual machine is deployed, it is not deployed to a particular datastore, but rather to a datastore cluster.
Storage DRS determines on which datastore to place the virtual machine, based on space utilization and
I/O load. Like traditional DRS, Storage DRS continuously monitors the cluster space utilization and also
monitors the I/O load using Storage I/O Control. If thresholds for space utilization or I/O response time
are exceeded, or if there is a significant difference in space utilization between the datastores within the
datastore cluster, Storage DRS attempts to relocate a virtual machine using Storage vMotion.