Vmkfstools
Command for directly working with the (virtual) disk at host level.
With this command you can destroy whole virtual machines if you do not take the right precautions (hint: BACKUPS) and are not familiar with the command.
Usage
vmkfstools [options] target
Whereby target can be either a physical disk, a virtual disk or a device.
The command is mostly known for using it to manipulate virtual disks. Beware that if you are working with a virtual disk that in most cases the virtual machine itself should be shut down.
Options
from the help page of the command.
OPTIONS FOR FILE SYSTEMS
vmkfstools -C --createfs [vmfs3|vmfs5]
-b --blocksize #[mMkK]
-S --setfsname fsName
-Z --spanfs span-partition
-G --growfs grown-partition
deviceName
-P --queryfs -h --humanreadable
-T --upgradevmfs
vmfsPath
OPTIONS FOR VIRTUAL DISKS
vmkfstools -c --createvirtualdisk #[gGmMkK]
-d --diskformat [zeroedthick|
thin|
eagerzeroedthick]
-a --adaptertype [buslogic|lsilogic|ide|
lsisas|pvscsi]
-w --writezeros
-j --inflatedisk
-k --eagerzero
-K --punchzero
-U --deletevirtualdisk
-E --renamevirtualdisk srcDisk
-i --clonevirtualdisk srcDisk
-d --diskformat [zeroedthick|
thin|
eagerzeroedthick|
rdm:<device>|rdmp:<device>|
2gbsparse]
-X --extendvirtualdisk #[gGmMkK]
[-d --diskformat eagerzeroedthick]
-M --migratevirtualdisk
-r --createrdm /vmfs/devices/disks/...
-q --queryrdm
-z --createrdmpassthru /vmfs/devices/disks/...
-v --verbose #
-g --geometry
-x --fix [check|repair]
-e --chainConsistent
vmfsPath
OPTIONS FOR DEVICES
-L --lock [reserve|release|lunreset|targetreset|busreset|readkeys|rea dresv] /vmfs/devices/disks/...
-B --breaklock /vmfs/devices/disks/...
vmkfstools -H --help
Examples
Export a VM disk
Export a VM disk in 2GB chunks, note that since ESXi 5.1+ the 2GB sparse driver is disabled.
vmkfstools -i /vmfs/volumes/storagename/YourVM/YourVM.vmdk -d 2gbsparse /vmfs/volumes/storage2/YourVM/YourVM.vmdk
Check or repair a disk
-x, --fix -[check|repair]
This option will check and/or repair the virtual disk in case of an unclean shutdown.
Example:
vmkfstools --fix check /vmfs/volumes/esx4-1-local-storage-1/dummy/dummy.vmdk Disk is error free
Set a UUID
-J, --miscop [setuuid | getuuid]
'setuuid´ option creates a unique identifier (UUID) for the virtual disk and stores the UUID in the descriptor file of the
virtual disk. If the descriptor file already contains a UUID, it will be overwritten with a new one.
Please make sure that the virtual disk does not have a UUID before using this option.
´getuuid´ option displays the UUID of the virtual disk.
dumpfs
dumpfs can be used by specifying either "-D | --dumpfs" and specifying a VMFS volume, file or folder.
Example:
# vmkfstools -D /vmfs/volumes/esx4-1-local-storage-1/ Lock [type 10c00001 offset 4292608 v 33, hb offset 3440640 gen 11, mode 0, owner 00000000-00000000-0000-000000000000 mtime 2509] Addr <4, 0, 0>, gen 1, links 4, type dir, flags 0, uid 0, gid 0, mode 1755 len 1260, nb 1 tbz 0, cow 0, zla 1, bs 1048576
activehosts
activehosts can be used by specifying "--activehosts" and specifying a VMFS volume
Example:
# vmkfstools --activehosts /vmfs/volumes/esx4-1-local-storage-1/ Found 1 actively heartbeating hosts on volume '/vmfs/volumes/esx4-1-local-storage-1/' (1): MAC address 00:50:56:92:3f:86
punchzero
Since vSphere 5.1 there's an option to shrink disks besides the normally required storage vmotion.
With the guest shut down you can run vmkfstools with the punchzero option.
Reclaim disk space by returning unused blocks of data in the virtual disk to the host OS.
Note that this will only work if your virtual disk is of type thin.
Before running it you will also need to zero out the unused blocks of data in the guest OS.
For a windows VM, you can use Microsoft's tool sdelete. Run it as
sdelete -z c:
Note that the -z option is needed as of sdelete version 1.6
For a linux based VM, run a command like:
cat /dev/zero > zero.fill;sync;sleep 1;sync;rm -f zero.fill
to zero out the unused space.
Note of warning that you should stop database -and other disk intensive- services before running the above.
Some more detailed descriptions and tips on zero-ing out data from your guest OS can be found at Shrink guest on hosted platform
Example:
# vmkfstools --punchzero disk.vmdk vmfsDisk: 1, rdmDisk: 0, blockSize: 1048576 Hole Punching: 3% done.
After you're done and list the VM from within the console, it looks like nothing has changed, in this example the disk is 10GB in size.
# ls -lh *.vmdk -rw------- 1 root root 10.0G Nov 27 20:58 disk-flat.vmdk -rw------- 1 root root 527 Nov 27 21:02 disk.vmdk
If you use the command du however then you can see the difference:
# du -hs *.vmdk 4.3G disk-flat.vmdk 0 disk.vmdk
You can also use the vSphere Client data browser to see the effect of reclaiming disk space.
If you try to run this command against a VM living on NFS storage you might end up seeing the following error:
vmkfstools --punchzero myvmdk.vmdk Not a supported filesystem type
The error is a bit confusing as you might expect vmkfstools to talk about the guest OS here, but it is actually reporting that NFS does not support the punchzero option.
Your solution is to either move the vmdk by hand to storage not located on VMFS or use storage vmotion to migrate to non NFS storage. On moving using storage vmotion, the zero data is already being discarded. So you can just storage vmotion back afterwards and you have reclaimed the lost disk space.
