Linked-clone virtual machines can be stored on local datastores, which are internal spare disks on ESXi hosts. Local storage offers advantages such as inexpensive hardware, fast virtual-machine provisioning, high performance power operations, and simple management. However, using local storage limits the vSphere infrastructure configuration options that are available to you. Using local storage is beneficial in certain Horizon 7 environments but not appropriate in others.
Using local datastores is most likely to work well if the Horizon 7 desktops in your environment are stateless. For example, you might use local datastores if you deploy stateless kiosks or classroom and training stations.
Consider using local datastores if your virtual machines have floating assignments, are not dedicated to individual end users, do not require persistent disks for user data, and can be deleted or refreshed at regular intervals such as on user logoff. This approach lets you control the disk usage on each local datastore without having to move or load-balance the virtual machines across datastores.
However, you must consider the restrictions that using local datastores imposes on your Horizon 7 desktop or farm deployment:
- You cannot use VMotion to manage volumes.
- You cannot load-balance virtual machines across a resource pool. For example, you cannot use the Composer rebalance operation with linked-clones that are stored on local datastores.
- You cannot use VMware High Availability.
- You cannot use the vSphere Distributed Resource Scheduler (DRS).
- You cannot store a Composer replica and linked clones on separate datastores if the replica is on a local datastore.
When you store linked clones on local datastores, VMware strongly recommends that you store the replica on the same volume as the linked clones. Although it is possible to store linked clones on local datastores and the replica on a shared datastore if all ESXi hosts in the cluster can access the replica, VMware does not recommend this configuration.
- If you select local spinning-disk drives, performance might not match that of a commercially available storage array. Local spinning-disk drives and a storage array might have similar capacity, but local spinning-disk drives do not have the same throughput as a storage array. Throughput increases as the number of spindles grows.
If you select direct attached solid-state disks (SSDs), performance is likely to exceed that of many storage arrays.
You can store linked clones on a local datastore without constraints if you configure the desktop pool or farm on a single ESXi host or a cluster that contains a single ESXi host. However, using a single ESXi host limits the size of the desktop pool or farm that you can configure.
To configure a large desktop pool or farm, you must select a cluster that contains multiple ESXi hosts with the collective capacity to support a large number of virtual machines.
If you intend to take advantage of the benefits of local storage, you must carefully consider the consequences of not having VMotion, HA, DRS, and other features available. If you manage local disk usage by controlling the number and disk growth of the virtual machines, if you use floating assignments and perform regular refresh and delete operations, you can successfully deploy linked clones to local datastores.