- VMware proprietary file system that is virtualization aware and optimized for virtualization.
- Supports concurrent access to shared storage.
- Can be expanded dynamically.
- Uses a 1 MB regular block size, for storing large virtual disk files.
- Uses sub-block addressing, storing small files: the sub-block size is 8 KB.
- If file size is less than 1 KB, file is stored in metadata space. No blocks/sub-blocks are used.
- If file size is more than 1 KB but less than 8 KB, sub-block is used to store the file.
- If file size is more than 8 KB, regular block is used.
- Provides on-disk, block-level locking.
- Maximum number of datastore per host: 1024
- Maximum number of paths : 4096
- Supported storage drives: 512n/512e
- Supported Sparse format: vmfsSparse for VMDKs less than 2 TB and SEsparse for VMDKs equal to or greater than 2 TB
There are 2 methods used under on-disk, block level locking as below.
- SCSI Reservations
- ATS (Atomic Test and Set) – Default method if storage has VAAI plugin support.