Post

Ranked #4 on Hacker News with 18 points and 14 comments.

Migrating a Synology NAS to a UniFi UNAS Pro 8 with Robocopy, SMB Multichannel, and Surprising Performance Traps

I’ve had a Synology NAS for a very long time , and recently I started moving its contents to a new Ubiquiti UniFi UNAS Pro 8 . This seemed like it ought to be a fairly boring operation. Both devices speak SMB, I have a fast network (recently upgraded to 10 gigabit internally), and Windows has had tools for copying files reliably between machines for decades. Naturally, it turned into a whole evening of learning things I thought I already knew, which is why I started a blog lol.

There was a nice bit of history here for me because back in 2007 (good lord!) I wrote a post called “ XCopy considered harmful - Robocopy or XXCopy or SyncBack .” My argument at the time was basically that once you are moving enough files, Explorer stops being the move and Robocopy starts looking pretty good. I even used /Z , Robocopy’s restartable mode, because being able to resume a partially transferred file was useful on unreliable connections.

Almost twenty years later, /Z turned out to be one of the most important things I needed to remove because it made everything hella slow.

The basic job was straightforward. I had shares on the Synology such as:

I initially used Explorer, mostly because it was there and because sometimes the easy thing really is the easy thing. That lasted until Explorer started producing errors on individual files: