When you are working on optimizing performance for your virtual machines, storage location is an important factor. Depending on your storage needs, you might select storage with high performance and high availability, or storage with lower performance.
Storage can be divided into different tiers depending on several factors:
High Tier. Offers high performance and high availability. Might offer built-in snapshots to facilitate backups and point-in-time (PiT) restorations. Supports replication, full storage processor redundancy, and SAS drives. Uses high-cost spindles.
Mid Tier. Offers mid-range performance, lower availability, some storage processor redundancy, and SCSI or SAS drives. Might offer snapshots. Uses medium-cost spindles.
Lower Tier. Offers low performance, little internal storage redundancy. Uses low-end SCSI drives or SATA.
Not all VMs must be on the highest-performance and most-available storage throughout their entire life cycle.
When you decide where to place a virtual machine, the following considerations apply:
Criticality of the VM
Performance and availability requirements
PiT restoration requirements
Backup and replication requirements
A virtual machine might change tiers throughout its life cycle because of changes in criticality or changes in technology. Criticality is relative and might change for various reasons, including changes in the organization, operational processes, regulatory requirements, disaster planning, and so on.