Migrating a Synology NAS to a UniFi UNAS Pro 8: Robocopy, SMB Multichannel, and Surprising Performance Traps
Migrating a Synology NAS to a UniFi UNAS Pro 8 with Robocopy, SMB Multichannel
Scott Hanselman migrates his Synology NAS to a UniFi UNAS Pro 8, discovering that Robocopy's /Z flag drastically slows transfers, alternate data streams cause cryptic errors, and SMB Multichannel lets an old Synology with four 1GbE ports hit 250 MB/s. He shares practical Robocopy commands and lessons on tuning for NAS-to-NAS copies.
What I had forgotten is that Microsoft’s current migration guidance specifically warns that /Z should be used cautiously because the extra logging required for restartability can significantly reduce copy performance.
- internet2000
Starting with robocopy is nuts. I'd have started with rsync and just let it run overnight. The peace of mind that it'd do the right thing and not needing to research flags are more than worth any speed tradeoffs.
- Neywiny
Sometimes when we Linux for a long time, we run into decades old friends: grep, sh, bc, whatever. Not uncommon to run a command that first released 50 years ago. Rarely on Windows do we get that. As much hate as windows gets, at least they left in more than just explorer drag and drop.
If the author is reading, it would be nice to clarify that the 10g network comment is irrelevant. I was under the impression at least 1 of the devices would have a 10g link, but at least 2 of the 3 didn't. It was a bit confusing, but it's also very late where I am.
- kalleboo
The Synology web UI lets you mount a remote SMB share and copy files directly in their file manager without making the round-trip via your PC, I imagine this would have been the fastest method without getting bogged down in command-line tools.
- bananamogul
"Ideally you'll find more value in the comments as Hacker News folks and Windows experts will drop in with better tools and strategies."
I don't know if this is better, but...an alternative is rclone, which uses rsync under the hood. It can also do parallel jobs and is restartable on any failed partial copy.
When I've had to do large Synology-to-Synology moves, that's what I've used. The multiple rsyncs in parallel really helps if you've got a lot of small files.
- abcd_f
He should've given bvckup2 a try.
Asynchronous IO, multithreaded for smaller files, serialized when they are big, block-level delta copying on subsequent runs. Pretty much as fast as it gets on Windows.