Update 1: While waiting on a replacement drive to arrive, another drive from the same array has failed. This is a rather unlikely coincidence which may mean some data loss, depending on the type of failure. We're now waiting for a second replacement drive to be installed, we won't be able to tell the extent of the data loss until then.
Update 2: All faulty drives have now been replaced, and we have been able to ascertain the nature of the failure. We are currently restoring from our cold backups, which will mean data loss of approximately two weeks. The tracker and IRC will be restored shortly, with the site returning after some further maintenance.

I would expect more from a tracker of this calibre.
Is it really that hard to maintain nightly/incremental backups?