VMSD file format: VMware snapshot dictionary

Introduction

The .vmsd file is the snapshot database of a VMware virtual machine: the centralised file in which the machine's snapshot information and metadata are stored, and the main source Snapshot Manager draws its tree from. A new machine starts with a small one, which grows as snapshots are taken. It sits beside the .vmx file as <name>.vmsd.

Structure

The file is the same key = "value" text as a .vmx file, including the .encoding line. VMware's article on Snapshot Manager and the backing files describes the schema: general entries for Snapshot Manager, named snapshot.…, and specific entries for each snapshot, named snapshotX.…, where X is an internal number that groups the entries of one snapshot (the first is snapshot0). X is not the hierarchy. The article says more entries exist than it lists.

Key	Meaning (VMware KB 337269)
`snapshot.numSnapshots`	The number of snapshots in the hierarchy; raised by one when a snapshot is taken, lowered when one is deleted, and deleted with `snapshot.current` when the last goes.
`snapshot.lastUID`	The most recently created snapshot UID, kept so that no UID repeats; incremented by one for every snapshot created.
`snapshot.current`	The UID of the current snapshot, the one the machine inherits from; updated by Go To to the `snapshotX.uid` of the snapshot chosen.
`snapshot.needConsolidate`	`TRUE` when the disk chain needs consolidation.
`snapshot.recordName`, `snapshotX.recordName`	Named in the article's schema as the general and per-snapshot record entries; the article does not describe their values.
`snapshotX.uid`	The snapshot's unique UID.
`snapshotX.displayName`	The name shown in Snapshot Manager.
`snapshotX.description`	The optional description.
`snapshotX.filename`	The .vmsn state file of the snapshot.
`snapshotX.numDisks`	The number of virtual disks.
`snapshotX.diskY.node`	The SCSI device ID of disk Y.
`snapshotX.diskY.fileName`	The disk file for that device ID in this snapshot: the redo-log (delta) disk that was current, so the files of a disk chain can be found.

.encoding = "UTF-8"
snapshot.lastUID = "2"
snapshot.current = "2"
snapshot.numSnapshots = "2"
snapshot0.uid = "1"
snapshot0.filename = "T-Snapshot1.vmsn"
snapshot0.displayName = "first"
snapshot0.numDisks = "1"
snapshot0.disk0.fileName = "T.vmdk"
snapshot0.disk0.node = "scsi0:0"

The start of a snapshot dictionary.

The viewer lists every snapshot, and reports a snapshot.numSnapshots that differs from the snapshots with a uid, a snapshot.current that is no snapshot's uid, a repeated uid, and a numDisks that does not match the disks listed.

Not described

Unknown

Reference: the key that links a snapshot to its parent is not named in the article read, so the page cannot say how the hierarchy is stored; the viewer shows it as a key that is not described.
Viewer: the same keys are shown as written and labelled not described, in the tree and in the All statements list.

.VMSD File Format

Introduction

Structure

Not described

Unknown

Links

Software

Reference