It depends on your environment. You might use filessystem links to access from a central place.
If you have a installation with many different machines you might use an external process (i.e. cron) to copy logfiles to a network device, it is not a good idea to have the logfiles direct on such device it might decrease the performance!
You might have a rolling-file-appender to switch the log every hour/x MB and copy/move after it is renamed.