HOME

TheInfoList



OR:

VMware VMFS (Virtual Machine File System) is
VMware VMware, Inc. is an American cloud computing and virtualization technology company with headquarters in Palo Alto, California. VMware was the first commercially successful company to virtualize the x86 architecture. VMware's desktop software ru ...
, Inc.'s
clustered file system A clustered file system is a file system which is shared by being simultaneously mounted on multiple servers. There are several approaches to clustering, most of which do not employ a clustered file system (only direct attached storage for e ...
used by the company's flagship server virtualization suite,
vSphere VMware vSphere (formerly VMware Infrastructure 4) is VMware's cloud computing virtualization platform. It includes an updated vCenter Configuration Manager, as well as vCenter Application Discovery Manager, and the ability of vMotion to move m ...
. It was developed to store virtual machine disk images, including snapshots. Multiple servers can read/write the same filesystem simultaneously while individual virtual machine files are locked. VMFS volumes can be logically "grown" (non-destructively increased in size) by spanning multiple VMFS volumes together.


Version history

There are six (plus one for vSAN) versions of VMFS, corresponding with ESX/ESXi Server product releases. * VMFS0 can be reported by ESX Server v6.5 as a VMFS version when a datastore is unmounted from a cluster/host. * VMFS1 was used by ESX Server v1.x. It did not feature the cluster filesystem properties and was used only by a single server at a time. VMFS1 is a flat filesystem with no directory structure. * VMFS2 is used by ESX Server v2.x and (in a limited capacity) v3.x. VMFS2 is a flat filesystem with no directory structure. * VMFS3 is used by ESX Server v3.x and vSphere 4.x. Notably, it introduces directory structure in the filesystem. * VMFS5 is used by vSphere 5.x. Notably, it raises the extent limit to 64 TB and the file size limit to 62 TB, though vSphere versions earlier than 5.5 are limited to VMDKs smaller than 2 TB. * VMFS6 is used by vSphere 6.5. It supports 512 emulation (512e) mode drives. * VMFS-L is the underlying file system for VSAN-1.0. Leaf level VSAN objects reside directly on VMFS-L volumes that are composed from server side direct attached storage (DAS). File system format is optimized for DAS. Optimization include aggressive caching with for the DAS use case, a stripped lock down lock manager and faster formats.


Features

* Allows access by multiple ESXi servers at the same time by implementing per-file locking. SCSI reservations are only implemented when logical unit number (LUN) metadata is updated (e.g. file name change, file size change, etc.) * Add or delete an ESXi server from a VMware VMFS volume without disrupting other ESXi servers. * With ESX/ESXi4, VMFS volumes can also be expanded using LUN expansion. * Optimize virtual machine I/O with adjustable volume, disk, file and block sizes. * Recover virtual machines faster and more reliably in the event of server failure with Distributed Journaling. * While present in previous versions automatic unmap was added to VMFS 6 allowing for automatic space reclamation requests which previously were manually actioned.


Limitations

* Can be shared with up to 64 ESXi Servers. * Maximum filesystem size is 50 TB as of VMFS3, and 62 TB as of VMFS5. * Maximum LUN size of 2 TB as of VMFS3 and 64 TB as of VMFS5. * In VMFS3 and VMFS5 prior to vSphere 5.1, the maximum number of hosts which can share a read-only file is 8. This affects the scalability of linked clones sharing the same base image. In vSphere 5.1, this limit is increased to 32 with the introduction of a new locking mechanism. * VMFS3 limits files to 262,144 (218) blocks, which translates to 256 GB for 1 MB block sizes (the default) up to 2 TB for 8 MB block sizes. * VMFS5 uses 1 MB blocks throughout (with
block suballocation Block suballocation is a feature of some computer file systems which allows large blocks or allocation units to be used while making efficient use of empty space at the end of large files, space which would otherwise be lost for other use to inter ...
for small files), and has a file size limit of 62 TB, though the VMDK size is restricted to 2 TB - 512 B in ESXi versions earlier than 5.5 due to a limitation in the version of SCSI emulated. * There is also a limit of approx 30,720 files (using MBR) on a single VMFS3 datastore. This has been raised to 130,690 files (using GPT) on VMFS5


Open source implementations


fluidOps Command Line Tool

A
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...
open source VMFS driverJava open source VMFS driver
/ref> enables read-only access to files and folders on partitions formatted with the Virtual Machine File System (VMFS) is developed and maintained b
fluid Operations
AG. It allows features like offloaded backups of virtual machines hosted on VMware ESXi hosts up to VMFSv3.


glandium VFS FUSE Mount

vmfs-tools supports more VMFS features and read only VMFS mounts through the standard
Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...
VFS and the
FUSE Fuse or FUSE may refer to: Devices * Fuse (electrical), a device used in electrical systems to protect against excessive current ** Fuse (automotive), a class of fuses for vehicles * Fuse (hydraulic), a device used in hydraulic systems to protect ...
framework. Developed by Christophe Fillot and Mike Hommey and available as source code download at th
glandium.orgvmfs-tools page
or the
Debian Debian (), also known as Debian GNU/Linux, is a Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of D ...
br>vmfs-tools
and
Ubuntu Ubuntu ( ) is a Linux distribution based on Debian and composed mostly of free and open-source software. Ubuntu is officially released in three editions: ''Desktop'', ''Server'', and ''Core'' for Internet of things devices and robots. All the ...
br>vmfs-tools
packages Package may refer to: Containers or Enclosures * Packaging and labeling, enclosing or protecting products * Mail, items larger than a letter * Chip package or chip carrier * Electronic packaging, in electrical engineering * Automotive package, ...
.


References

{{reflist


External links


VMFS Technical Overview and Best Practices
- VMware, Inc.

- VMware, Inc.
Open Source VMFS Implementation
- Project vmfs VMware Proprietary software Shared disk file systems Virtualization software