Are there tools to check the FS for inconsistencies and stuff.
There's this debian server that has been running for a few years and never been checked. Or is this unneccesary? It has been hard-rebooted (powerfailurel) a few times.
There are tools to check this on any linux distribution. They are however filesystem specific and the partition must be umounted to run them.
Look at the manpage for fsck if it is an ext2/ext3 partition.