Failed to upload the chunk : rename input/output error

I am getting the following error at the same point in a large backup. The backup is of a VM. There are two snapshots already. The destination contains many backups (single destination multiple sources).

It gets to 98.2% then fails with:

2020-11-18 01:42:46.281 INFO UPLOAD_PROGRESS Skipped chunk 16214 size 7784940, 11.69MB/s 00:02:05 98.2%
2020-11-18 01:42:46.917 ERROR UPLOAD_CHUNK Failed to upload the chunk 23bc91e8225541af5d131e7d3e0319ed61644fb4849964e54d51b65d80471cbf: rename /Volumes/MACBOOK/BACKUPS/chunks/23/bc91e8225541af5d131e7d3e0319ed61644fb4849964e54d51b65d80471cbf.jvsfkrkf.tmp /Volumes/MACBOOK/BACKUPS/chunks/23/bc91e8225541af5d131e7d3e0319ed61644fb4849964e54d51b65d80471cbf: input/output error

Neither the source nor the target of the rename exist (so I presume the upload failed in some undetected way).

The destination is on a mounted (on macos) SMB drive (shared from a USB disk on a windows machine) across a gigabit lan. The destination has 2TB free space, so its not an out of space issue (my first thought).

duplicacy check -all reports all good (as I would expect)

What is odd is that it consistently fails at exactly the same point. Could it be open files or some other resource limit being reached?

Not sure what can cause this. Maybe you should run a disk check, or dmesg to see if there is any disk error.

I checked events viewer for disk errors, nothing there.
SMART says everything is fine.
Chkdisk did report removing some unnecessary link files in an unrelated duplicacy storage folder.

Subsequently backed up another 200GB (using tar and another deduping backup tool) without any issues.

Just duplicacy that is having an issue and very specifically at the same point in the backup. I will try a backup to a new storage folder when I get chance.

The error in your original post is most definitely disk issue.

I’m confused, are you running it on a mac or windows?

What filesystem is on a disk?

In your second comment you mention chkdsk which is windows tool, so I assume NTFS

I would recommend running surface scan: chkdsk /r and after (and if) that succeeds check reallocated sector count with the drive vendor tools

If both pass and no reallocated sectors — the next suspect is disk/sata controller. Is that an usb enclosure?

Not sure why you would be confused, I described the setup in my initial post.

I think at this point it is unlikely to be a disk problem, especially given I have successfully backed up a further 200GB to the file system without issue using various other utilities.

A controller failing would almost certainly produce random effects, not fail at exactly the same point in the same way each time.

There may be some kind of corruption in the target repository, though a duplicacy check passes, and I will (time premitting) backup to a newly created repository to rule that out.

Run chkdsk /r on windows on that disk, otherwise it’s baseless speculation. Duplicacy is a user mode software it cannot generate disk IO errors.

Successful backup of subsequent data has nothing to do with the existing sector failure.

Repository corruption won’t result in IO errors. And repository is a just a bunch of files. Check passes because chunk files exist.

Run check disk with /r and look at disk smart attributes as well.

That is all provided your network is reliable. But I guess it’s a given.

You can try to create a random file in that directory by hand, maybe with the exact same name and at least a few MB in size, then rename it to see if you’ll get the same error.


Virus Scanner (Windows Defender) deleting that particular chunk. I only discovered this because after many attempts over the past days, this evening (just now 1am) windows defender decides to actually alert me that it has disabled a threat.

Having scanned inside the VM for viruses, and it being clear, the solution is to add the duplicacy storage folder to exclusions

Windows Security 
-> Virus & threat detection
 -> Virus and threat protection settings
  -> Manage Settings
   -> Exclusions
    -> Add or remove exclusions
     -> Add an exclusion