The physical storage design must meet the capacity and performance requirements that are defined by the logical storage design, and these requirements must be mapped back to the design factors.

The logical storage design identifies the capacity, IOPS, and throughput that are required to support the vSphere design. The design factors identify the functional requirements, such as availability and recoverability, and any constraints that may be placed on the physical design, such as using an array from a specific vendor or using a specific storage protocol.

The logical storage design specifications are as follows:

• Storage capacity: 16 TB
• Storage IOPS: 6,250
• I/O profile: 8 k
• I/O size: 90% Read/10% Write
• Total storage throughput: 55 MB/s
• Number of virtual machines per datastore: 20
• Datastore size: 2.5 TB

The factors that influence the physical storage design are as follows:

• Shared or local storage
• Block storage or file storage
• Array specifications, such as active/active or active/passive, the number of storage processors, and the cache
• Storage protocol that uses fiber channel, iSCSI, NFS, or Fiber Channel over Ethernet (FCoE), as well as the type and number of disks and the RAID configuration
• Support for VMware integration: vStorage APIs for Array Integration (VAAI) and vSphere APIs for Storage Awareness (VASA)
• Support for advanced storage technologies: deduplication, tiering, and flash-based cache
• The Recovery Point Objective (RPO), which is the amount of data that will not be lost in the event of a disaster, and the Recovery Time Objective (RTO), which is the amount of time it takes to recover the system and data in the event of a disaster

The chief considerations when choosing a storage platform are IOPS, throughput, and support for features such as VAAI, VASA, SRM, and accelerated backups. The physical storage design should focus on both performance and capacity. The physical storage design must be able to meet the performance requirements of the design.

Meeting the design capacity requirements is typically easy to accomplish, but ensuring that the storage will meet the performance requirements takes a bit more work. The I/O profile of the workloads, the number of IOPS required, the types of disks used, and the RAID level that is selected all have an impact on the storage performance. It is good practice to first design the storage to meet the performance requirements, and then design it to meet the capacity requirements.