The transparent snapshots creation process (Figure 12) is as follows:
- After the full sync is complete, PowerProtect Data Manager issues a snapshot creation operation.
- PowerProtect Data Manager requests a sync operation against vCenter.
- The API calls are passed to the ESXi host after the location is resolved. In this step, the TSDM has no active role because no data transfer occurs.
- The ESXi host communicates with the relevant VM asset using VAIO, and the snapshot is persisted to the Snapshot Extent Store (SES).
Note: The Snapshot Extent Store (SES) is dynamically created during snapshot creation and is deleted when the snapshot is retired. The SES stores the bitmaps that correspond to the data in the disk at that time. The SES uses thin-allocated space across the overall datastore space and does not affect the specific VM quota.
- Using the SES, the VAIO filter takes the bitmap in memory and saves it. Because all of it is bitmap-based, creating the transparent snapshot is fast, which reduces the read/write latency.
- After the bitmap is persisted, the filter can start tracking changes on the disk again, using a new bitmap.
- The snapshot operation is marked as finished. PowerProtect Data Manager can use the VM Direct Engine to access the vCenter level task completion and get the snapshot UUID that was created.
Figure 12. Transparent snapshot creation