The VMware Virtual Machine File System (VMFS) is a high-performance clustered file system designed by VMware, Inc., specifically for storing virtual machine files in VMware’s virtualization platform. VMFS is used to manage and organize the various files associated with virtual machines, including virtual disks, configuration files, snapshots, and more. It is an integral part of VMware’s vSphere suite, which includes products like VMware ESXi and VMware vCenter Server.

Key features and aspects of the VMware Virtual Machine File System (VMFS) include:

1. Clustered File System: VMFS is a clustered file system, meaning it is designed to be used in environments where multiple hosts need access to the same storage concurrently. This enables features like vMotion and High Availability (HA) to work effectively.
2. Shared Storage: VMFS is ideal for environments where multiple VMware hosts need to access the same storage repository to run virtual machines. Shared storage is a prerequisite for features like vMotion, where VMs can be moved from one host to another seamlessly.
3. Optimized for Virtual Machines: VMFS is designed and optimized to handle the I/O patterns and performance characteristics of virtual machines. It provides features like file-level locking and efficient caching to enhance performance.
4. Datastores: In VMware environments, storage managed by VMFS is presented to hosts as datastores. A datastore is a storage container that hosts virtual machine files. VMFS datastores can reside on various types of storage systems, including SAN (Storage Area Network) and NAS (Network Attached Storage).
5. Block-Level Sharing: VMFS employs a block-level locking mechanism to allow multiple hosts to read and write to the same virtual disk files concurrently without risking data corruption.
6. Snapshots and Clones: VMFS supports features like snapshots and clones, allowing administrators to take point-in-time snapshots of virtual machines and create clones of VMs for testing or provisioning.
7. Compatibility and Scalability: VMFS is compatible with various types of storage hardware and is designed to scale as more hosts and virtual machines are added to the environment.
8. Storage vMotion: VMFS supports Storage vMotion, which enables the migration of a virtual machine’s storage from one datastore to another without disrupting the VM’s operation.
9. Thin Provisioning: VMFS supports thin provisioning, which allows virtual disks to be provisioned with only the space they initially need, with additional space allocated as needed.
10. Automatic Space Reclamation: VMFS supports features like VAAI (vStorage APIs for Array Integration) which allow storage arrays to communicate with the hypervisor to perform storage operations more efficiently, including space reclamation.

VMware Virtual Machine File System plays a critical role in enabling efficient storage management and the mobility of virtual machines in VMware environments. It allows multiple hosts to access shared storage, facilitating features like live migration (vMotion) and improved resource utilization.