I have started to tar and compress older autoburt snapshot files to free up disk space - the snapshots saved so far consume over 1TB on disk, which is about 25% of the capacity of the /ligo filesystem.  Currently the plan is to retain roughly the last three months of data in it's uncompressed form, with data older than that retained on disk in a compressed tar archive only.  Files will be archived by month (so all of the files from a given month will be in a single tarball).  Since the snapshot files are all ASCII text, they should compress down well.  This should also speed up the rsync backups, since there will no longer be 2.8 million files to traverse looking for changes.  If you need assistance accessing older snapshot files stored in the tar archives, please see one of the CDS admins.