NAS540 backup not working

MV10

I have two NAS540s, call them NAS1 and NAS2. Normally NAS1 performs a scheduled daily mirror backup to NAS2, and we only actually use NAS1. Due to drive hours, I began to replace the drives in NAS2. I pulled the first one and the rebuild completed yesterday afternoon without issues. Both NASes appear healthy and normal.

The Backup Planner shows for yesterday: "Failed, connection broken". Also, oddly, nothing is shown for today (the job is scheduled at 10AM and it is now past 11AM). It shows the next run as tomorrow at 10AM.

If I select that job and press the Play button on the toolbar, nothing seems to happen, it still shows "waiting".

The general logs under Maintenance shows "connection broken in data stream" and nothing else, including after I try to start the job manually.

MV10

Upon re-checking the backup target after a long period of time, it seems backups are actually happening but very, very slowly. There are a lot of 100GB+ virtual machine disk images and I see one that is being copied (filename prefixed with "." and suffixed with a temporary extension). Overnight about half of the 100GB size has been copied.

I suppose the backup operations just have terrible logging / status info, at least through the web GUI.

If there's a way to SSH and get better status / logs, I'd love to know about it.

Eventually I will be overhauling these entirely. The new drives are much larger and I need to switch to RAID10 so I'll temporarily only have one copy of my data. I really need to know when the backup is actually valid.

I'm surprised at the terrible performance. If I manually copy these images to the NAS from a PC, it takes maybe 3 hours … this thing is going on maybe 12 hours now and is only half done.