vSphere Storage API’s Array Integration (VAAI)
These are Hardware Acceleration API’s that help arrays to integrate with vSphere for offloading certain storage operation to an array. It reduces CPU overhead on a host.
They also provide Array Thin Provisioning APIs which help to monitor space use on thin-provisioned storage arrays to prevent out-of-space conditions, and to perform space reclamation.
Features on vSAN:
- Scalable Lock Management
- Reduces lock-related overheads
- Speeds up admin tasks
- Increases I/O performance for thin VMDKs
- Extended Copy (full copy, copy offload or xcopy)
- Allows copy operations to take place on the array, rather than having to transfer data to and from the host
- Block zeroing
- Speeds up the creation of eager-zeroed thick disks and can improve first-time write performance on lazy-zeroed thick disks and on thin disks.
- Speeds up the creation of eager-zeroed thick disks and can improve first-time write performance on lazy-zeroed thick disks and on thin disks.
- Dead space reclamation
- Allows hosts to convey to storage which blocks are no longer in use.
vSphere Storage API’s for Storage Awareness
These are API’s, either supplied by third-party vendors or offered by VMware, which enable communication between vCenter Server and underlying storage. With VASA, storage entities can inform vCenter about their configurations, capabilities and storage health and events. In return, VASA can deliver VM storage requirements from vCenter Server to a storage entity and ensure that the storage layer meets the requirements.
Vasa is essential for vVols, vSAN and storage policies.
Array thin provisioning API’s helps monitor space usage on thin-provisioned storage arrays to prevent out-of-space conditions and performs space reclamation when data is deleted
PSA is a shortcut for Pluggable Storage Architecture and is a collection of APIs used by storage vendors to create and deliver specific multipathing and load-balancing plug-ins that are best optimized for specific storage arrays. To manage storage multipathing ESXi uses a special VMkernel layer.
Native Multipathing Plugin or NMP is an extensible module that manages sub plugins.
- Storage Array Type Plugins (SATP)
- Path Selection Plugins (PSP)
If more multipathing functionality is required, third-party plugins can be installed
- Manages physical path claiming and unclaiming
- Registers and de-registers logical devices
- Associates physical paths with logical devices
- Processes I/O requests to logical devices
