NetWorker: vProxy Performance mode cloning loses optimization with Retention Lock devices

• Backup or cloning may appear slower than expected for NetWorker VMware Protection (NVP) vProxy save sets on Retention Lock devices
• Error appears in ddfs.info log despite apparent success of backup or clone job:
  • NetWorker: How To Collect ddfs.info log from Data Domain

Attempt to rename non-empty directory /data/col1/mtree/device/active/abc3b7ed-00000006-fd27be29-6627be29-00045000-595e3c56
dboost-<nsrsvr.demo.local-55146>: ddboost_api ERROR: ddp_rename() failed, FromPath //mtree/device/active/abc3b7ed-00000006-fd27be29-6627be29-00045000-595e3c56, ToPath //mtree/device/21/06/abc3b7ed-00000006-fd27be29-6627be29-00045000-595e3c56,  Err: 5034-nfs rename failed (nfs: Permission denied)

• Impacted NetWorker releases:
  • 19.9.0.x (and prior)
  • 19.10.0.0 through 19.10.0.4
  • 19.11.0.0 and 19.11.0.1

The problem results from an undiscovered flaw in implementation. Since Data Domain Retention-locked devices do not allow renaming of non-empty directories, part of NetWorker's normal backup and clone workflow silently fails, falling back to a different mechanism which prevents optimization success.

The workflow in the following NetWorker releases:

• 19.10.0.5
• 19.11.0.2
• 19.12+

Workaround:

The problem does not appear to affect Capacity Mode. Switching to Capacity Mode as a workaround may alleviate the problem in the short-term, but upgrade will be recommended.
 
 

 

NetWorker supports two types of backup optimization modes for vProxy backup to Data Domain systems—Optimized for Capacity, and Optimized for Performance. You can apply the optimization mode to vProxy protection groups during backup. The Optimized for Capacity mode uses variable size segmentation, which produces more overhead in data processing due to the higher deduplication rate, but reduces the capacity consumed on the Data Domain system. Optimized for Performance provides performance improvements during incremental back ups of virtual machines using Changed Block Tracking (CBT) and replicates data to a Data Domain system, and is effective when backing up large VMDK files. Although Optimized for Performance results in additional space use on the Data Domain device (around 20%), this mode significantly improves random I/O performance for instant access restores.