The throughput for /b/ is 60TB per month, yet ironically enough, the FBI has a complete copy of every post on /b/ since Jan. 2005, with the exceptions of only a few posts. This archive encompasses two vaults of harddrives, which put-together amount to about 1280TB of images and 3GB of post data. One of these vaults is in Washington D.C, the other is somewhere in Montana.
/b/ is mirrored by server 11.227.1.3 every 45 secounds, which then dispences the data to the two reposetories in Montana and Washington. Agents then go through this data recursively. Right now they are at about June of 2006 and the gap between the investigated posts and present day continues to widen. The budget for this undertaking is are $16.5M a year and rising annually.