There is an issue running 7z on Synology DS1812+ (tested with DSM 4.0-2228 and DSM 4.1-2236).
7z a backup.file.7z /directory_to_backup -v5m
7-Zip 9.20 Copyright (C) 1999-2010 Igor Pavlov 2010-11-18
p7zip Version 9.20 (locale=C,Utf16=off,HugeFiles=on,4 CPUs)
Without "-v5m" switch, 7z is running like a charm. Adding -ms=off doesn't fix the problem.
Do you know this error ? Is it a bug ?
Remove backup.file.7z before operation.
Solved. Thank you very very much :-)