Pruning Performance of Aged Deduplicated Jobs on a Disk is Slow

If you are experiencing pruning performance issues, you can troubleshoot them by performing the following basic operations.

Symptoms

Pruning performance of CommServe job records to be deleted or the deduplication database (DDB) prunable block count is low.

Resolution

To improve the performance of the deduplication pruning, complete one of the following tasks.

• Ensure that the DDB is hosted on a server with high-speed processor and effective memory that delivers good deduplication performance. Depending on your environment, relocate the DDB to a storage that meets the performance requirements associated with Deduplication operations. See Move the Deduplication Database for instructions. To ensure optimal performance for deduplication operations, the disk hosting the DDB must satisfy the specifications mentioned in Deduplication Building Block Guide.
• Set the minimum reserve space on a mount path to 10% of the disk size. For example, if the disk size of the mount path is 100 GB, set the Reserve Space to 10 GB. See Establish Space Allocation on the Mount Path for instructions.
• Enable Disk Write Cache on the disk that is hosting the disk library and the DDB. For instructions, refer the KB259716 Microsoft Knowledge Base article on http://support.microsoft.com/.
• If the pruning is slow on the disk library hosted on the Windows MediaAgent due to low disk IO operations and throughput, install the Microsoft hot fixes KB982383 and KB2769701. For more information, refer the KB982383 and KB2769701 Microsoft Knowledge Base article on http://support.microsoft.com/.
• Modify the Microsoft Multipath I/O settings based on the issues explained in the Updated Guidance on Microsoft MPIO Settings.
• Verify the Windows System Event log for any errors referencing to the mount path containing the aged data.
• Check if any antivirus security software is in process of scanning the CV_MAGNETIC folder on library mount paths. The Antivirus security software scan can prevent the pruning process. Therefore, exclude the CV_MAGNETIC folder from the antivirus security software scan.
• Defragment the disk library volumes. See Fragmentation Analysis for instructions.
• For UNIX or Linux MediaAgents, if disk library mount paths are using NFS share, ensure the following:
  • actimeo mount option value is set other than 0.
  • sync option is not set for the mount.
• If the CommServe job records to be deleted count is higher and is not reducing, then ensure the following:
  • Both the mount path and the MediaAgent are accessible
  • Pruning is enabled on the DDB store/mount path
  • The data verification job (specifically phase 1) has not been running for long
  • All the partitions of the DDB are online
• If the CommServe job records to be deleted count is higher and is not reducing on a cloud library for a particular DDB store, then ensure that the pruner MediaAgent is configured. For more details, see SetDeviceControllerProps.
• If DDB prunable count is not reducing on the disk library or the cloud library, then check for the following:
  • Mount path is accessible
  • Pruning is enabled on the DDB store/mount path
  • All the partitions of the DDB are online
• For setups that are on SP13 or higher, if the DDB prunable count is not reducing on the disk library and the default 4 threads are already in use, then you can use the DedupPrunerThreadPoolSizeDisk additional setting to increase the number of threads.
• For setups that are on SP13 or higher, if the DDB prunable count is not reducing on the cloud library and the default 10 threads are already in use, then you can use the DedupPrunerThreadPoolSizeCloud additional setting to increase the number of threads.
• You can also verify the counters in the SIDBPrune log to identify the time taken for physical deletion for each operation:

Example:

9160  35b0  01/22 03:09:12 ### stat- ID [Avg Flush], Samples [13], Time [0.013359] Sec(s), Average [0.001028] Sec/Sample 9160  35b0  01/22 03:09:12 ### stat- ID [Avg Finalize], Samples [1], Time [14.809450] Sec(s), Average [14.809450] Sec/Sample 9160  35b0  01/22 03:09:12 ### stat- ID [Avg Update], Samples [1261], Time [0.001281] Sec(s), Average [0.000001] Sec/Sample 9160  35b0  01/22 03:09:12 ### stat- ID [Avg Search], Samples [633], Time [0.029269] Sec(s), Average [0.000046] Sec/Sample 9160  35b0  01/22 03:09:12 ### stat- ID [Avg GetDirContents], Samples [1], Time [0.000878] Sec(s), Average [0.000878] Sec/Sample