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Delphix

Space on Delphix Not Reclaimed by Log Retention -TB005

Alert Type

Availability

Impact

When LogSync is enabled for a SQL Server data source, the Delphix Engine retains a copy of the transaction log files from the related data source. These log files are expired and automatically deleted by the Delphix Engine according to a retention policy that is configurable by the Delphix administrator, but that defaults to one week. As a result of the issue described by this alert, the storage space on the Delphix Engine may not be reclaimed when the transaction log files are deleted. Consequently, Delphix storage pool utilization will continue to grow until it reaches a threshold (85%), at which point new provisions and SnapSync will no longer function. Higher storage pool utilization can also impact the performance of the Delphix Engine. See the Additional Information section below for specific details.

Contributing Factors

The issue occurs in the following Delphix software releases:

  • All 3.0 releases
  • Delphix Engine 3.1 releases through 3.1.5.0
  • Delphix Engine 3.2 releases through 3.2.1.0

The issue is applicable only for SQL Server data sources which have LogSync enabled.

Symptoms

The storage used for the impacted data source will keep increasing, as seen in the Capacity screen in the Delphix Admin application.

The error message that occurs when a provision or snap sync fails due to exceeding the storage threshold is:

"This operation is not allowed due to lack of space."

Resolution

The issue is addressed in the following Delphix releases:

  • Delphix Engine 3.1.5.1 and later releases
  • Delphix Engine 3.2.2.0 and later releases

Upon upgrading to one of the releases containing the resolution, all newly deleted transactions logs will have their space correctly reclaimed.

Transaction logs expired by retention policy prior to upgrading will not have their space correctly reclaimed; however, Delphix Support can perform a special procedure to reclaim such space. Since both the Delphix Engine upgrade and procedure require a service outage, it is recommended that the two be combined. Please contact Delphix Support or file a Support case to schedule assistance. 

Additional Information

When storage utilization on the Delphix Engine reaches high levels, overall performance may be negatively impacted, including virtual database (VDB) performance. Please see the Delphix Technical Bulletin:

High Pool Utilization May Result in Poor VDB Performance for more information.