Thank you all for your responses.
I've now run the check with -vv. It looks like the data was uploaded without corruption, but the check failed.
- As far as I can tell, "rclone check" made no attempt to retry the one failed transfer, despite the default apparently being 3 attempts. The file that says "Failed to download" in the log below never appeared in the log again.
- A failed transfer is reported as a "difference" at the end of the check
The log says "3 differences found", but then on the last line it also says "1 differences found", which is a bit confusing.
Full log included below.
2020/06/09 12:24:40 DEBUG : rclone: Version "v1.52.0" starting with parameters ["rclone" "--transfers" "1" "--bwlimit=0.5M" "-vv" "-P" "check" "--download" "XXXXX" "XXXXX"]
2020/06/09 12:24:40 DEBUG : Using config file from "/home/user/.config/rclone/rclone.conf"
2020/06/09 12:24:40 INFO : Starting bandwidth limiter at 512kBytes/s
2020-06-09 12:24:41 DEBUG : mega root 'XXXXX': Waiting for checks to finish
2020-06-09 12:24:42 DEBUG : XXXXX: OK
2020-06-09 12:24:42 DEBUG : XXXXX: OK
2020-06-09 12:24:42 DEBUG : XXXXX: OK
2020-06-09 12:24:42 DEBUG : XXXXX: OK
2020-06-09 12:24:55 DEBUG : XXXXX: OK
2020-06-09 12:24:57 DEBUG : XXXXX: OK
2020-06-09 12:25:12 DEBUG : XXXXX: OK
2020-06-09 12:25:13 DEBUG : XXXXX: OK
2020-06-09 12:25:14 DEBUG : XXXXX: OK
2020-06-09 12:25:15 DEBUG : XXXXX: OK
2020-06-09 12:28:14 DEBUG : XXXXX: OK
2020-06-09 12:28:16 DEBUG : XXXXX: OK
2020-06-09 12:28:26 DEBUG : XXXXX: OK
2020-06-09 12:34:16 ERROR : XXXXX: Failed to download: read tcp XXXXX: read: connection reset by peer
2020-06-09 12:34:17 DEBUG : XXXXX: OK
2020-06-09 13:08:25 DEBUG : XXXXX: OK
2020-06-09 13:08:27 DEBUG : XXXXX: OK
2020-06-09 13:42:34 DEBUG : XXXXX: OK
2020-06-09 13:42:35 DEBUG : XXXXX: OK
2020-06-09 14:16:43 DEBUG : XXXXX: OK
2020-06-09 14:16:44 DEBUG : XXXXX: OK
2020-06-09 14:50:53 DEBUG : XXXXX: OK
2020-06-09 14:50:55 DEBUG : XXXXX: OK
2020-06-09 15:25:03 DEBUG : XXXXX: OK
2020-06-09 15:25:04 DEBUG : XXXXX: OK
2020-06-09 15:59:12 DEBUG : XXXXX: OK
2020-06-09 15:59:14 DEBUG : XXXXX: OK
2020-06-09 16:30:00 INFO : *go-mega*: pollEvents: Error from server: 500 Server Too Busy
2020-06-09 16:33:21 DEBUG : XXXXX: OK
2020-06-09 16:33:24 DEBUG : XXXXX: OK
2020-06-09 17:07:32 DEBUG : XXXXX: OK
2020-06-09 17:07:34 DEBUG : XXXXX: OK
2020-06-09 17:41:41 DEBUG : XXXXX: OK
2020-06-09 17:41:43 DEBUG : XXXXX: OK
2020-06-09 18:15:50 DEBUG : XXXXX: OK
2020-06-09 18:15:53 DEBUG : XXXXX: OK
2020-06-09 18:40:16 INFO : *go-mega*: pollEvents: Error from server: 500 Server Too Busy
2020-06-09 18:50:00 DEBUG : XXXXX: OK
2020-06-09 18:50:01 DEBUG : XXXXX: OK
2020-06-09 19:24:09 DEBUG : XXXXX: OK
2020-06-09 19:24:10 DEBUG : XXXXX: OK
2020-06-09 19:35:20 INFO : *go-mega*: pollEvents: Error from server: 500 Server Too Busy
2020-06-09 19:58:18 DEBUG : XXXXX: OK
2020-06-09 19:58:19 DEBUG : XXXXX: OK
2020-06-09 20:32:27 DEBUG : XXXXX: OK
2020-06-09 20:32:29 DEBUG : XXXXX: OK
2020-06-09 21:06:36 DEBUG : XXXXX: OK
2020-06-09 21:06:39 DEBUG : XXXXX: OK
2020-06-09 21:40:45 DEBUG : XXXXX: OK
2020-06-09 21:40:46 DEBUG : XXXXX: OK
2020-06-09 22:14:54 DEBUG : XXXXX: OK
2020-06-09 22:14:57 DEBUG : XXXXX: OK
2020-06-09 22:49:04 DEBUG : XXXXX: OK
2020-06-09 22:49:07 DEBUG : XXXXX: OK
2020-06-09 23:23:14 DEBUG : XXXXX: OK
2020-06-09 23:23:17 DEBUG : XXXXX: OK
2020-06-09 23:25:38 INFO : *go-mega*: pollEvents: Error from server: 500 Server Too Busy
2020-06-09 23:25:39 INFO : *go-mega*: pollEvents: Error from server: 500 Server Too Busy
2020-06-09 23:57:24 DEBUG : XXXXX: OK
2020-06-09 23:57:26 DEBUG : XXXXX: OK
2020-06-10 00:31:33 DEBUG : XXXXX: OK
2020-06-10 00:31:35 DEBUG : XXXXX: OK
2020-06-10 01:05:41 DEBUG : XXXXX: OK
2020-06-10 01:05:44 DEBUG : XXXXX: OK
2020-06-10 01:39:51 DEBUG : XXXXX: OK
2020-06-10 01:39:53 DEBUG : XXXXX: OK
2020-06-10 02:14:00 DEBUG : XXXXX: OK
2020-06-10 02:14:03 DEBUG : XXXXX: OK
2020-06-10 02:48:09 DEBUG : XXXXX: OK
2020-06-10 02:48:10 DEBUG : XXXXX: OK
2020-06-10 03:22:18 DEBUG : XXXXX: OK
2020-06-10 03:22:21 DEBUG : XXXXX: OK
2020-06-10 03:56:27 DEBUG : XXXXX: OK
2020-06-10 03:56:30 DEBUG : XXXXX: OK
2020-06-10 04:21:03 INFO : *go-mega*: pollEvents: Error from server: 500 Server Too Busy
2020-06-10 04:30:37 DEBUG : XXXXX: OK
2020-06-10 04:30:39 DEBUG : XXXXX: OK
2020-06-10 05:04:46 DEBUG : XXXXX: OK
2020-06-10 05:04:47 DEBUG : XXXXX: OK
2020-06-10 05:38:56 DEBUG : XXXXX: OK
2020-06-10 05:38:58 DEBUG : XXXXX: OK
2020-06-10 06:13:04 DEBUG : XXXXX: OK
2020-06-10 06:13:07 DEBUG : XXXXX: OK
2020-06-10 06:47:14 DEBUG : XXXXX: OK
2020-06-10 06:47:16 DEBUG : XXXXX: OK
2020-06-10 07:14:38 DEBUG : XXXXX: OK
2020-06-10 07:14:41 DEBUG : XXXXX: OK
2020-06-10 07:14:41 NOTICE: mega root 'XXXXX': 3 differences found
2020-06-10 07:14:41 NOTICE: mega root 'XXXXX': 80 matching files
Transferred: 33.105G / 33.105 GBytes, 100%, 511.993 kBytes/s, ETA 0s
Errors: 4 (retrying may help)
Checks: 81 / 81, 100%
Transferred: 160 / 160, 100%
Elapsed time: 18h49m59.9s
2020/06/10 07:14:41 DEBUG : 13 go routines active
2020/06/10 07:14:41 Failed to check with 4 errors: last error was: 1 differences found