vSphere VMFS-5

vSphere 5.0 introduces a new version of vSphere VMFS (VMFS), VMFS-5, which contains many important architectural changes that enable greater scalability and performance while reducing complexity. Although numerous fundamental changes have been made, the following enhancements are significant from operationaland architectural aspects:

• 64TB device support
• Unified block size
• Improved subblock mechanism

vSphere 5.0 facilitates a nondisruptive upgrade from VMFS-3 to VMFS-5, ensuring consistency across virtual infrastructures. The unified block size, 1MB, enables easier deployments and reduced complexity from an architectural and operational aspect while maintaining the scalability and the flexibility that were previously found only with large block sizes. It should be noted that volumes that are upgraded from VMFS-3 to VMFS-5 will retain their original block size, because modifying the block size would require a reformat of the volume. Toenable greater scalability and reduce storage overhead associated with small files, various enhancements have been made to VMFS-5. These enhancements include optimized subblock sizes and the allocation of these blocks. They have resulted in support for large volumes (64TB on a single extent) and higher virtual machine density while reducing the overhead associated with small files. VMFS-5 is capable of allocating 30.000 subblocks of 8KB for files such as log files and virtual machine metadata (.vmx files). For files with a size smaller than 1KB, “small file blocks” are used. The following table depicts the most significant architectural changes for VMFS-5 in comparison to VMFS-3.