Block Storage Service
Third-Party Volume Management
ZStack ZStone supports the onboarding of third-party block storage volumes. Block storage volumes created on third-party platforms can be automatically synchronized to ZStack ZStone management interface and displayed separately from local volumes.
Volume Migration
- Migration Initialization: When migrating a volume, the system creates a new target volume and links the source volume to the target volume. Similar to tiered volumes, if a read request targets an uninitialized data region in the target volume, the internal mechanism redirects the read operation to the source volume. When writing data to an uninitialized data region in the target volume, the system internally performs a deep copy, transferring the overlapping source volume data to the target volume.
- Migration Execution: Executing migration performs a deep copy of all initialized blocks from the source volume to the target volume in the background. This step can be performed concurrently while the client uses the new target volume.
- Migration Finalization: After the background migration completes, you can commit or terminate the migration. Committing the migration removes the cross-link between the source and target volumes and deletes the source volume. Terminating the migration removes the cross-link and deletes the target volume.
Volume Cloning
ZStack ZStone supports cloning multiple block storage volumes from a single volume snapshot, offering both linked clones and independent clones.
Linked cloning is implemented based on snapshot layering and the Copy-on-Write (COW) mechanism. First, the system creates a read-only snapshot of the original block storage volume. Then, the original data is copied to multiple clone volumes through COW technology. These clone volumes share the same physical storage space and only perform data copying when modifications occur, thereby significantly saving storage capacity.
A linked clone volume has a dependency relationship with its source snapshot. ZStack ZStone supports breaking this dependency chain, converting a linked clone volume into an independent volume.