WD Sync vs drag & drop


I recently purchased a WD My Book Duo and My Cloud PR2100 for business use. My intended work flow is straightforward:

  1. Backup important camera RAW files to the Duo (RAID 1)
  2. Sync these files to the PR2100 (to be located offsite)

Both devices are currently at home for testing. The Duo is connected to my desktop via USB 3.0 and the PR2100 via LAN using GbE.

I have tested both WD Sync and drag & drop between the two storage units (the PR2100 is mapped as a network drive) and have observed different transfer speeds, see graph below.

The period of faster transfer was after I paused WD Sync and used drag & drop to transfer the same data to the mapped PR2100. Once completed, I restarted WD Sync, leading to a rapid drop in transfer rate. WD Sync is working at approx. 5 MB/s while drag & drop operates around 27 MB/s.

I have read this post in an attempt to understand the reason for this difference but have not found an answer. Full disclosure: I am a complete novice when it comes to NAS etc.

As I understand it, I cannot use the drag & drop feature once this device is located offsite without being connected to its network via VPN. My preference therefore to use WD Sync but the speeds are very slow. Can anyone offer a reason for the different rates?

If it is any use, the Crystal Disk Mark score for the mapped PR2100 is below.


Thanks in advance!