Today a borgbackup ran into exception due to insufficient free space.

I´d like borgbackup to limit cache size so that there is enough free space on filesystem. Ideally with an option to determine the limit in percent and/or size. This is not about reducing cache size needs, but about making sure that it will not abort the backup in out of space conditions – even if by continuing without cache.

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/borg/archiver.py", line 1684, in main
exit_code = archiver.run(args)
File "/usr/lib/python3/dist-packages/borg/archiver.py", line 1621, in run
return args.func(args)
File "/usr/lib/python3/dist-packages/borg/archiver.py", line 82, in wrapper
do_files=getattr(args, 'cache_files', False), lock_wait=self.lock_wait) as cache_:
File "/usr/lib/python3/dist-packages/borg/cache.py", line 86, in init
self.sync()
File "/usr/lib/python3/dist-packages/borg/cache.py", line 355, in sync
self.begin_txn()
File "/usr/lib/python3/dist-packages/borg/cache.py", line 187, in begin_txn
shutil.copy(os.path.join(self.path, 'files'), txn_dir)
File "/usr/lib/python3.5/shutil.py", line 235, in copy
copyfile(src, dst, follow_symlinks=follow_symlinks)
File "/usr/lib/python3.5/shutil.py", line 116, in copyfile
copyfileobj(fsrc, fdst)
File "/usr/lib/python3.5/shutil.py", line 76, in copyfileobj
fdst.write(buf)
OSError: [Errno 28] No space left on device