Something seems terribly wrong here...

 PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
18631 bacula    15   0 5580m 3.5g 1236 S  100 90.9  68:38.75 bacula-dir

Seriously.

It's trying to do a restore here. Yes, the backup contains a lot of data, but not that much.

It's going to OOM, I'm afraid.