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Delphix

Reclamation of Free Space May Be Delayed (TB013)

Impact

The Delphix Engine manages database space for all database objects on the server. When objects such as dSources or Virtual Databases (VDBs) are deleted, either via explicit action or automatically via retention policies, the Delphix Engine reclaims the previously used space in the background. As a result of the issue described in this alert, the reclamation of free space may occur more slowly than expected.

Availability of databases may be impacted, especially in cases where large dSources or VDBs are deleted. If there is insufficient free space, re-creation of these objects may be blocked until sufficient free space is reclaimed.

Contributing Factors

This issue affects appliances running Delphix Engine 2.6.x, Delphix Engine 2.7.0, Delphix Engine 2.7.1, or Delphix Engine 2.7.2

The rate at which free space is reclaimed under affected releases of Delphix Engine is dependent on the performance of the underlying storage.

Releases of Delphix Engine 2.6.x are more adversely impacted by the problem than other affected releases.

Symptoms

Following deletion of database objects, free space may be reclaimed more slowly than expected.

Available space is displayed  in the Graph View of the Resources > Capacity screen. Until Dephix has reclaimed free space, there may be periods where the available free space does not reflect the difference between space allocated to current databases objects and total capacity.

When free space is less than expected, operations such as creation of new dSources, creation of new VDBs, VDB refreshes, or snapshots may fail. Space checks for new dSources require a quantity of free space on the Delphix Engine equal to 50% of the size of the physical database.

Relief/Workaround

Storage will continue to be freed, albeit at a slower rate. A simple workaround is to wait until there is sufficient space before creating new dSources or Virtual Databases. Free space may be monitored by checking the Graph View of the Resources > Capacity screen.

Alternatively, maintain sufficient free space such that new allocations can be satisfied even before old space is reclaimed.

Resolution

A final resolution is available in Delphix Engine 2.7.3 and later releases.