ONLINE SNAPSHOT CONSOLIDATION USING I/O MIRRORING

摘要

To create a backup of a live (running) virtual machine, a backup agent may take a snapshot of the virtual machine, backup the virtual machine from the snapshot disk, and delete the snapshot. Deleting the snapshot initiates a snapshot consolidation process where delta disks of the virtual machine are collapsed. A virtual disk layer sets up a mirror driver between a current virtual disk and a target virtual disk. Data sectors of the delta disk are copied over to the target virtual disk in a single pass, while the mirror driver mirrors write request for the current virtual disk to the target virtual disk.

主权项

1. A method for consolidating snapshots of a virtual machine, comprising:
creating a mirror driver between a current disk handle representing a disk chain comprising a base disk and a delta disk and a target disk handle representing a target disk in the disk chain into which the delta disk is to be consolidated; copying sectors from the delta disk to the target disk in a single iteration while the virtual machine is running; and responsive to receiving a first disk request from the virtual machine to write data to the current disk handle, while the sectors are being copied, replicating the first disk request to create a second disk request to write the data to the target disk handle.