Failure to backup large files

I have a recurrent problem when I backup to a external USB HD. I have told Windows Defender to ignore the restic repository data directory on the E drive. One of my drives works almost all the time. A second one fails regularly when storing very large files, such as VM images. When these failures occur, it appears that the USB HD is effectively ejected and automatically re-mounted, leading to a slew of errors from restic, and subsequent restic check failures, requiring a restic prune, and re-try of the restic backup.

I would like to be able to keep two or more copies of the backups on different external USB HDs, without having to get different enclosures or 2.5" HDs.

I am not using the latest restic because I am not confident about changing the version of the client from the one used for the older backups.

My amateur analysis of the event log suggests that something related to log journals is a problem.

OS: Win 10 home, all updates installed.
restic version: 0.9.3 from

I’m not sure what’s going on here, it feels to me that it’s a problem with the enclosure and/or the USB connection. Restic writes files (but not so many in parallel) during backup, but that’s about it.

You can do that, it’s fully backwards compatible. But I suspect it won’t help with your problem, we did not change much in the archiver code between 0.9.3 and 0.9.4…