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Confirming a virtual machine's snapshot delta disk layout (1027887)

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Purpose

This article provides instructions on reviewing virtual machine snapshot configurations and detailing snapshot delta disk trees.

Resolution

The virtual machine's snapshot database (.vmsd file) contains information about the snapshot layout and disk delta sequence for a virtual machine. This database is interpreted for the VMware vSphere or Infrastructure Client, and lists existing virtual machine snapshots as a whole. It does not go into detail about the individual delta disk files which make up part of the virtual machine's snapshot state. For such information, you must log into the ESXi/ESX host terminal.

Note: If the snapshot manager does not contain any snapshot entries, yet the virtual machine continues to run snapshot delta disks, see Committing snapshots when there are no snapshot entries in the Snapshot Manager (1002310).

Confirming a virtual machine's snapshot delta disk layout using the ESXi/ESX host terminal

Note: For instructions on logging into an ESXi/ESX host terminal, see the Additional Information section of this article.

If you have multiple virtual machine disks located across other datastores, the delta disks for all virtual disks are by default stored in the same location. For example:
/vmfs/volumes/datastore1/examplevm/examplevm.vmdk
/vmfs/volumes/datastore2/examplevm/examplevm_secondary_disk.vmdk
When a virtual machine snapshot is created, all attached non-independent disks are snapshotted simultaneously. As such, there will be one delta disk per virtual machine disk, per snapshot. The colors above indicate what delta disks are related to either specific base disk. Thus, the three snapshots would have created a total of six delta files in datastore1/examplevm:
/vmfs/volumes/datastore1/examplevm/examplevm-000001.vmdk
/vmfs/volumes/datastore1/examplevm/examplevm-000002.vmdk
/vmfs/volumes/datastore1/examplevm/examplevm-000003.vmdk
/vmfs/volumes/datastore1/examplevm/examplevm-000004.vmdk
/vmfs/volumes/datastore1/examplevm/examplevm-000005.vmdk
/vmfs/volumes/datastore1/examplevm/examplevm-000006.vmdk
...
/vmfs/volumes/datastore1/examplevm/examplevm.vmdk
/vmfs/volumes/datastore1/examplevm/examplevm.vmx
Further details are required to understand which snapshot delta file relates to any one disk. The ordering of these snapshots should also be understood. Run the following command tTo lay out the snapshot delta disk tree, run the command:
grep -A2 parentFile examplevm-???????.vmdk | grep -v "#"
You see output similar to:
examplevm-000001.vmdk:parentFileNameHint="examplevm.vmdk"
examplevm-000001.vmdk-RW 41943040 VMFSSPARSE "examplevm-000001-delta.vmdk"
--
examplevm-000002.vmdk:parentFileNameHint="examplevm-000001.vmdk"
examplevm-000002.vmdk-RW 41943040 VMFSSPARSE "examplevm-000002-delta.vmdk"
--
examplevm-000003.vmdk:parentFileNameHint="examplevm-000002.vmdk"
examplevm-000003.vmdk-RW 41943040 VMFSSPARSE "examplevm-000003-delta.vmdk"
This indicates that the descriptor file examplevm-000003.vmdk has an extent (stored delta information) of examplevm-000003-delta.vmdk. It uses examplevm-000002.vmdk as its parent disk, which uses examplevm-000001.vmdk as its parent.

Ultimately, examplevm-000001.vmdk uses examplevm.vmdk as its parent, which is the base disk for the virtual machine.

Alternatively, if there were additional snapshotted disks to consider, the tree layout may appear similar to:
examplevm-000001.vmdk:parentFileNameHint="examplevm.vmdk"
examplevm-000001.vmdk-RW 41943040 VMFSSPARSE "examplevm-000001-delta.vmdk"
--
examplevm-000002.vmdk:parentFileNameHint="/vmfs/volumes/4b96afb0-b2474ede-fc0b-001aa004abc2/examplevm/examplevm_1.vmdk"
examplevm-000002.vmdk-RW 23123440 VMFSSPARSE "examplevm-000002-delta.vmdk"
--
examplevm-000003.vmdk:parentFileNameHint="examplevm-000001.vmdk"
examplevm-000003.vmdk-RW 41943040 VMFSSPARSE "examplevm-000003-delta.vmdk"
--
examplevm-000004.vmdk:parentFileNameHint="examplevm-000002.vmdk"
examplevm-000004.vmdk-RW 23123440 VMFSSPARSE "examplevm-000004-delta.vmdk"
--
examplevm-000005.vmdk:parentFileNameHint="examplevm-000003.vmdk"
examplevm-000005.vmdk-RW 41943040 VMFSSPARSE "examplevm-000005-delta.vmdk"
--
examplevm-000006.vmdk:parentFileNameHint="examplevm-000004.vmdk"
examplevm-000006.vmdk-RW 23123440 VMFSSPARSE "examplevm-000006-delta.vmdk"
In this case, the odd-numbered snapshot delta disks are related to the first virtual hard disk, and the even-numbered files are related to the secondary virtual hard disk.

Note: Absolute paths suggest that the extent or disk is located on another datastore. Relative paths are used for files in the same directory.

Additional Information

Logging into an ESXi/ESX host terminal


Virtual machine snapshots and delta disks

See Also

Request a Product Feature

To request a new product feature or to provide feedback on a VMware product, please visit the Request a Product Feature page.

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