VMware Virtual SAN is a software-defined storage tier, available with vSphere 5.5 Update 1 or a later release, that virtualizes the local physical storage disks available on a cluster of vSphere hosts. You specify only one datastore when creating an automated desktop pool or an automated farm, and the various components, such as virtual machine files, replicas, user data, and operating system files, are placed on the appropriate solid-state drive (SSD) disks or direct-attached hard disks (HDDs).
Virtual SAN implements a policy-based approach to storage management. When you use Virtual SAN, View defines virtual machine storage requirements, such as capacity, performance, and availability, in the form of default storage policy profiles, which you can modify. Storage is provisioned and automatically configured according to the assigned policies. You can use Virtual SAN for linked-clone desktop pools, full-clone desktop pools, or an automated farm.
Each virtual machine maintains its policy regardless of its physical location in the cluster. If the policy becomes noncompliant because of a host, disk, or network failure, or workload changes, Virtual SAN reconfigures the data of the affected virtual machines and load-balances to meet the policies of each virtual machine.
While supporting VMware features that require shared storage, such as HA, vMotion, and DRS, Virtual SAN eliminates the need for an external shared storage infrastructure and simplifies storage configuration and virtual machine provisioning activities.
The Virtual SAN feature available with vSphere 6.0 and later releases contains many performance improvements over the feature that was available with vSphere 5.5 Update 1. With vSphere 6.0 this feature also has broader HCL (hardware compatibility) support. Also, VMware Virtual SAN 6.0 supports an all-flash architecture that uses flash-based devices for both caching and persistent storage.
Virtual SAN Workflow in View
Use vCenter Server 5.5 Update 1 or a later release to enable Virtual SAN. For more information about Virtual SAN in vSphere 5.5 Update 1, see the vSphere Storage document. For more information about Virtual SAN in vSphere 6 or later, see the Administering VMware Virtual SAN document.
When creating an automated desktop pool or an automated farm in View Administrator, under Storage Policy Management, select Use VMware Virtual SAN, and select the Virtual SAN datastore to use.
After you select Use VMware Virtual SAN, only Virtual SAN datastores are displayed.
Default storage policy profiles are created according to the options you choose. For example, if you create a linked-clone, floating desktop pool, a replica disk profile and an operating system disk profile are automatically created. If you create a linked-clone, persistent desktop pool, a replica disk profile and a persistent disk profile are created. For an automated farm, a replica disk profile is created. For both types of desktop pools and automated farms, a profile is created for virtual machine files.
To move existing View Composer desktop pools from another type of datastore to a Virtual SAN datastore, in View Administrator, edit the pool to deselect the old datastore and select the Virtual SAN datastore instead, and use the Rebalance command. This operation is not possible for automated farms because you cannot rebalance an automated farm .
(Optional) Use vCenter Server to modify the parameters of the storage policy profiles, which include things like the number of failures to tolerate and the amount of SSD read cache to reserve.
The names of the policies are OS_DISK (for operating system files), PERSISTENT_DISK (for user data files), REPLICA_DISK (for replicas), and VM_HOME (for virtual machine files such as .vmx and .vmsn files). Changes to the policy are propagated to newly created virtual machines and to all existing virtual machines in the desktop pool or the automated farm.
Use vCenter Server to monitor the Virtual SAN cluster and the disks that participate in the datastore. For more information, see the vSphere Storage document and the vSphere Monitoring and Performance documentation. For vSphere 6 or later, see the Administering VMware Virtual SAN document.
(Optional) For View Composer linked-clone desktop pools, use the Refresh and Recompose commands as you normally would. For automated farms, only the Recompose command is supported, regardless of the type of datastore.
Requirements and Limitations
The Virtual SAN feature has the following limitations when used in a View deployment:
This release does not support using the View space-efficient disk format feature, which reclaims disk space by wiping and shrinking disks.
Virtual SAN does not support the View Composer Array Integration (VAAI) feature because Virtual SAN does not use NAS devices.
Virtual SAN datastores are not compatible with Virtual Volumes datastores for this release.
Virtual SAN is compatible with the View Storage Accelerator feature. Virtual SAN provides a caching layer on SSD disks, and the View Storage Accelerator feature provides a content-based cache that reduces IOPS and improves performance during boot storms.
The Virtual SAN feature has the following requirements:
vSphere 5.5 Update 1 or a later release.
Appropriate hardware. For example, VMware recommends a 10GB NIC and at least one SSD and one HDD for each capacity-contributing node. For specifics, see the VMware Compatibility Guide.
A cluster of at least three ESXi hosts. You need enough ESXi hosts to accommodate your setup. For more information, see the vSphere Configuration Maximums document, available from https://www.vmware.com/support/pubs/vsphere-esxi-vcenter-server-pubs.html.
SSD capacity that is at least 10 percent of HDD capacity.
Enough HDDs to accommodate your setup. Do not exceed more than 75% utilization on a magnetic disk.
For more information about Virtual SAN requirements, see "Working with Virtual SAN" in the vSphere 5.5 Update 1 Storage document. For vSphere 6 or later, see the Administering VMware Virtual SAN document. For guidance on sizing and designing the key components of View virtual desktop infrastructures for VMware Virtual SAN, see the white paper at http://www.vmware.com/files/pdf/products/vsan/VMW-TMD-Virt-SAN-Dsn-Szing-Guid-Horizon-View.pdf.