rsync gives misleading error message when out of disc space

[richelbilderbeek]

Thanks for rsync! Here I have a bug/suggestion that would make it even better :-)

Summary: I was downloading files from a remote to a local disk. Unaware to me, the local disk was full. It was only until I added --ignore-checksum that the real/correct error message was shown. Here I suggest to give the error message earlier.

Detailed: Here a more step-by-step and detailed view on this problem.

This was my first approach:

# General
rclone copy [source] [target]
# Full code I used
rclone copy marcels-room-sftp:/homes/Zebrafish/Image_Data/1_Raw/Novo_Nordisk_Raw/1_CDKN1A temp_rsync/ --config=rclone.conf

The error I got:

2026/05/19 11:59:40 NOTICE: Failed to copy with 4406 errors:
last error was: corrupted on transfer: md5 hashes differ src(
sftp://Zebrafish@130.238.241.229:22//homes/Zebrafish/Image_Da
ta/1_Raw/Novo_Nordisk_Raw/1_CDKN1A) "" vs dst(Local file syst
em at //?/C:/cygwin64/home/Leica-Admin/marcel_zip_20260512/te
mp_rsync) "198955c877aa91af2d90a56f19e6d76f"

Note that the error points to different md5 hashes, where the src hash is "" (i.e. two double quotes). In hindsight, this error was caused because of lack of disk space. My suggestion is to change the error to indicate this lack of disk space.

My next step, was to use only the size as a checksum (although it was the lack of local harddisk space that was the actual problem):

# General
rclone copy [source] [target] --size-only
# Full code I used
rclone copy marcels-room-sftp:/homes/Zebrafish/Image_Data/1_Raw/Novo_Nordisk_Raw/1_CDKN1A temp_rsync/ --size-only --config=rclone.conf

I got this error:

2026/05/19 12:25:09 ERROR : InsH2Bfabp_CD15_09dpf_VAST02_plate01_CDKN1A_200723/InsH2Bfabp_CD15_09dpf_VAST02_plate01_CDKN1A_200723_dispensed.txt.18901e13.partial: corrupted on transfer: md5 hashes differ src(sftp://Zebrafish@130.238.241.229:22//homes/Zebrafish/Image_Data/1_Raw/Novo_Nordisk_Raw/1_CDKN1A) "" vs dst(Local file system at //?/C:/cygwin64/home/Leica-Admin/marcel_zip_20260512/temp_rsync) "771fad582d71328ccb98d82cf697ed87"
2026/05/19 12:25:11 ERROR : .DS_Store: Failed to calculate src hash: failed to calculate md5 hash: failed to run "md5sum /homes/Zebrafish/Image_Data/1_Raw/Novo_Nordisk_Raw/1_CDKN1A/.DS_Store": md5sum: /homes/Zebrafish/Image_Data/1_Raw/Novo_Nordisk_Raw/1_CDKN1A/.DS_Store: No such file or directory: Process exited with status 1

Again, the error points to different md5 hashes, where the src hash is "" (i.e. two double quotes). In hindsight, this error was caused because of lack of disk space. My suggestion is to change the error to indicate this lack of disk space.

Only when I started using --ignore-checksum the actual error cause became visible:

# General
rclone copy [source] [target] --ignore-checksum
# Full code I used
rclone copy marcels-room-sftp:/homes/Zebrafish/Image_Data/1_Raw/Novo_Nordisk_Raw/1_CDKN1A temp_rsync/ --ignore-checksum --config=rclone.conf

which gave the correct error message:

2026/05/19 12:52:32 NOTICE: InsH2Bfabp_CD15_10dpf_VAST02_plate01_CDKN1A_200804/InsH2Bf
abp_CD15_10dpf_VAST02_plate01_CDKN1A_200804_W_A01_1_6.tiff.6f34fd64.partial: Removing
partially written file on error: write \\?\C:\cygdrive\d\richel_20260519\Synology\InsH
2Bfabp_CD15_10dpf_VAST02_plate01_CDKN1A_200804\InsH2Bfabp_CD15_10dpf_VAST02_plate01_CD
KN1A_200804_W_A01_1_6.tiff.6f34fd64.partial: There is not enough space on the disk.

I would enjoy seeing 'There is not enough space on the disk' already in the first usages of rsync.

I can imagine this is hard to write a test for :-) . Thanks again for rsync!