VMware VMFS
Developer(s) | VMware, Inc. |
---|---|
Full name | Virtual Machine File System |
Introduced | with ESX Server v1.x |
Partition IDs | 0xfb (MBR) |
Limits | |
Max volume size | 64 TB (VMFS5)[1] |
Max file size | 62 TB[2][3] |
Maxno.of files | ~130,690 (VMFS5)[2] |
Features | |
Transparent compression | No |
Transparent encryption | No |
Data deduplication | No |
Other | |
Supported operating systems | VMware ESX |
VMware VMFS(Virtual Machine File System) isVMware,Inc.'sclustered file systemused by the company's flagship server virtualization suite,vSphere.It was developed to storevirtual 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
[edit]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 aflat filesystemwith 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,[2]though vSphere versions earlier than 5.5 are limited to VMDKs smaller than 2 TB.[4]
- VMFS6 is used by vSphere 6.5. It supports512 emulation (512e)mode drives.[5]
- 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
[edit]- Allows access by multiple ESXi servers at the same time by implementing per-file locking. SCSI reservations are only implemented whenlogical 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
[edit]- Can be shared with up to 64 ESXi Servers.[6]
- Maximum filesystem size is 50 TB as of VMFS3, and 62 TB as of VMFS5.[6]
- Maximum LUN size of 2 TB as of VMFS3[6]and 64 TB as of VMFS5.[1]
- 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.[7][8]
- 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.[6]
- VMFS5 uses 1 MB blocks throughout (withblock suballocationfor small files), and has a file size limit of 62 TB,[2]though the VMDK size is restricted to 2 TB - 512 B in ESXi versions earlier than 5.5[4]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[4]
Open source implementations
[edit]fluidOps Command Line Tool
[edit]AJavaopen source VMFS driver[9]enables read-only access to files and folders on partitions formatted with the Virtual Machine File System (VMFS) is developed and maintained byfluid OperationsArchived2011-08-21 at theWayback MachineAG.It allows features like offloaded backups of virtual machines hosted on VMware ESXi hosts up to VMFSv3.
glandium VFS FUSE Mount
[edit]vmfs-toolssupports more VMFS features and read only VMFS mounts through the standardLinuxVFSand theFUSEframework. Developed by Christophe Fillot and Mike Hommey and available as source code download at theglandium.orgvmfs-tools pageor theDebianvmfs-toolsandUbuntuvmfs-toolspackages.
References
[edit]- ^ab"vSphere 5.0 Storage Features Part 1 - VMFS5".VMware. 2011-07-12.Retrieved2012-01-05.
- ^abcd"Configuration Maximums: VMware vSphere 5.5"(PDF).VMware. 2014-03-14.Retrieved2014-03-25.
- ^"What's New in vSphere 5.5 Storage"(PDF).VMware. 2013-08-27.Retrieved2014-03-25.
- ^abc"Configuration Maximums"(PDF).VMware® vSphere 5.0.
- ^"Technical White Paper: What's New in VMware vSphere 6.5"(PDF).VMware.
- ^abcd"Configuration Maximums for VMware vSphere 4.1"(PDF).VMware. 2010-07-13.Retrieved2010-07-13.
- ^"VMFS3 Limitation".VMware.
- ^"vSphere 5.1 New Storage Features".VMware.
- ^Java open source VMFS driver
External links
[edit]- VMFS Technical Overview and Best Practices- VMware, Inc.
- VMware VMFS product page- VMware, Inc.
- Open Source VMFS Implementation- Project vmfs