I have a Linux log server where multiple applications write data. Data is written in bursts, and in a lot of different files. I need to make a backup of this mess, preferably preserving as much coherence between the file versions as possible and avoiding getting truncated files. Total amount of data on the server is about 100Gb. What I really would want (but can't) is to shut-down, backup the system cold and then start it up again.
What kind of guarantees against concurrent modification does the various backup tools give? When do they "freeze" the file versions? I am looking at rsync, dump and tar at the moment, but I am open for other (open source) alternatives.
Changing the application or blocking writing for backups is sadly not an option. System is not running LVM (yet), but I have considered that for rebuilding the system and then snapshots.