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Image cloning in VMware ESX shell

VMware image clone via ESX shell and vmkfstools

The free version of the VMware vSphere Hypervisor has a reduced feature set. One of the missing features is the ability to clone or create templates from existing vms. You can clone an image using vmkfstools within the ESX shell.

vmkfstools

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
           -y --reclaimBlocks vmfsPath [--reclaimBlocksUnit #blocks]

OPTIONS FOR VIRTUAL DISKS:

vmkfstools -c --createvirtualdisk #[gGmMkK]
               -d --diskformat [zeroedthick
                               |thin
                               |eagerzeroedthick
                               ]
               -a --adaptertype [buslogic|lsilogic|ide
                                |lsisas|pvscsi]
               -W --objecttype [file|vsan]
               --policyFile <fileName>
           -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]
               -W --object [file|vsan]
               --policyFile <fileName>
               -N --avoidnativeclone
           -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
           -Q --objecttype name/value pair
           --uniqueblocks childDisk
   vmfsPath

OPTIONS FOR DEVICES:

           -L --lock [reserve|release|lunreset|targetreset|busreset|readkeys|readresv
                     ] /vmfs/devices/disks/...
           -B --breaklock /vmfs/devices/disks/...

vmkfstools -H --help

Identify source image and destination location

Log into the ESX sever and identify the location of the source image. In this example I will be cloning image centos-0 on datastore-1

~ # cd vmfs/volumes/datastore-1/
/vmfs/volumes/datastore-1 # ls
centos-0

I am going to create 3 additional CentOS vm images. Create the destination directory/s prior to running vmkfstools.

/vmfs/volumes/datastore-1 # mkdir centos-1 centos-2 centos-3
/vmfs/volumes/datastore-1 # ls
centos-0  centos-1  centos-2  centos-3

Clone the image via vmkfstools -i source destination. If not specified the new image will be thick provisioned. The first will use the vmkfstools command without additional options. The 2nd and 3rd will thin provision.

Thin - These virtual disks do not reserve space on the VMFS filesystem, nor do they reserve space on the back-end storage. They only consume blocks when data is written to disk from within the VM/Guest OS. The amount of actual space consumed by the VMDK starts out small, but grows in size as the Guest OS commits more I/O to disk, up to a maximum size set at VMDK creation time. The Guest OS believes that it has the maximum disk size available to it as storage space from the start.

Thick (aka LazyZeroedThick) – These disks reserve space on the VMFS filesystem but there is an interesting caveat. Although they are called thick disks, they behave similar to thinly provisioned disks. Disk blocks are only used on the back-end (array) when they get written to inside in the VM/Guest OS. Again, the Guest OS inside this VM thinks it has this maximum size from the start.

EagerZeroedThick – These virtual disks reserve space on the VMFS filesystem and zero out the disk blocks at creation time. This disk type may take a little longer to create as it zeroes out the blocks, but its performance should be optimal from deployment time (no overhead in zeroing out disk blocks on-demand, meaning no latency incurred from the zeroing operation). However, if the array supports the VAAI Zero primitive which offloads the zero operation to the array, then the additional time to create the zeroed out VMDK should be minimal.

/vmfs/volumes/datastore-1 # vmkfstools -i centos-0/centos-0.vmdk centos-1/centos-1.vmdk
Destination disk format: VMFS zeroedthick
Cloning disk 'centos-0/centos-0.vmdk'...
Clone: 100% done.

/vmfs/volumes/datastore-1 # ls -la centos-1/
total 16778248
drwxr-xr-x    1 root     root           560 Feb  3 18:27 .
drwxr-xr-t    1 root     root          1820 Feb  3 18:17 ..
-rw-------    1 root     root     17179869184 Feb  3 18:25 centos-1-flat.vmdk
-rw-------    1 root     root           524 Feb  3 18:27 centos-1.vmdk

Clone a 2nd copy to the centos-2 directory. Specify -d thin to thin provision this image.

/vmfs/volumes/datastore-1 # vmkfstools -i centos-0/centos-0.vmdk centos-2/centos-2.vmdk -d thin
Destination disk format: VMFS thin-provisioned
Cloning disk 'centos-0/centos-0.vmdk'...
Clone: 100% done.

/vmfs/volumes/datastore-1 # ls -la centos-2/
total 1471496
drwxr-xr-x    1 root     root           560 Feb  3 18:36 .
drwxr-xr-t    1 root     root          1820 Feb  3 18:17   ..
-rw-------    1 root     root     17179869184 Feb  3 18:34 centos-2-flat.vmdk
-rw-------    1 root     root           550 Feb  3 18:36 centos-2.vmdk

Clone a 3rd copy to the centos-3 directory

/vmfs/volumes/datastore-1 # vmkfstools -i centos-0/centos-0.vmdk centos-3/centos-3.vmdk -d thin
Destination disk format: VMFS thin-provisioned
Cloning disk 'centos-0/centos-0.vmdk'...
Clone: 100% done.

/vmfs/volumes/datastore-1 # ls -la centos-3/
total 1471496
drwxr-xr-x    1 root     root           560 Feb  3 18:42 .
drwxr-xr-t    1 root     root          1820 Feb  3 18:17 ..
-rw-------    1 root     root     17179869184 Feb  3 18:40 centos-3-flat.vmdk
-rw-------    1 root     root           550 Feb  3 18:42 centos-3.vmdk

3 new copies of the CentOS vmdk files have been created. The vmkfstools command does not copy any of the additional files from within the source directory. I will add some details on this at a later time. For this example the cloned images will be added via the vSphere Client.

Add the newly cloned images to the vSphere inventory.

Log into the vSphere Client and add a New Virtual Machine (Ctrl-N).

Step through the New Virtual Machine Wizard taking note of Configuration and Select a Disk pages. Select Custom from the Configuration step of the Configuration wizard. vsphere-config-custom

Select Use an existing virtual disk. from the Select a Disk step of the Configuration wizrd. vsphere-config-existing