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New vStorage APIs
vStorage APIs are a collection of interfaces that third-party vendors can use to seamlessly interact with data storage in vSphere. There are four categories of vStorage APIs:
Array integration. These APIs are being co-developed with specific storage vendors. When complete, they will allow access to array-oriented capabilities such as array-based snapshots, hardware-offloaded storage device locking, integration between VMware and array-level thin provisioning, storage provisioning, data replication and more. In some cases, greater efficiencies may be realized by allowing the storage array to perform certain operations. VM cloning or template-based deployment can be hardware accelerated by array offloads rather than file-level copy operations at the ESX server. Storage VMotion would be able to leverage the storage array features to copy data more rapidly and with less ESX host impact; and rather than the traditional "SCSI lock" mechanism used by VMware, the array can lock only specific blocks being updated, which dramatically increases the number of VMs that can be deployed on a data store.
Multipathing. These APIs are used by the Pluggable Storage Architecture to allow storage vendors to more intelligently use multipathing for better storage I/O throughput and storage
path failover. Storage vendors must certify their multipathing extensions modules with VMware for use with ESX(i). There are several vStorage multipathing APIs: A path selection plug-in (PSP) can extend the path selection algorithms for any given I/O; a storage array-type plug-in (SATP) allows new/changed path discovery and ongoing path state management; and a multipathing plug-in (MPP) can extend the entire path management model of vSphere, including path management and path selection.
Site Recovery Manager (SRM). These APIs are used to integrate SRM with array-based replication for block and NAS storage to allow SRM to seamlessly handle both VM and host failover and storage replication failover. They also allow SRM to control the underlying array-based replication that it relies on.
Data protection. These APIs replace VMware Consolidated Backup (VCB) that was introduced in VI3. While they include VCB functionality, they also add new features such as changed block tracking and the ability to directly interact with the contents of virtual disks via the VDDK. These APIs are for backup and data protection application vendors to provide better integration.
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This was first published in January 2010