When working on large files (> ~10GB) the file system can become fatelly corrupted. The system will crash (freeze), and unable to reboot (Grub reports 'Error 2'). Loading from a live/recovery disk and trying to fsck the corrupted filesystem yeilds multiples error.
I have trashed two system running Jaunty (Alpha 3 and Alpha 6) on Ext4 root file system. Both times I was manipulating/using large files. The first time occuired when I simply removed a 48GB file (system frooze), and the second time when VMWare was writing to a virtual disk (large file). Both system had all updates installed (2.6.27-11 kernel)
I've attached a screen shot of part of the ensuing fsck. This is after all(?) the master (global?) blocks have been decalred invalid.If you can't see from the picture, at this stage fsck is reporting multiply-claimed blocks (by the large files being used at the time, and random smaller files).
The system was a new dual processor (Core Duo X9100) Thinkpad W500 running on a 2.5" SATA drive, 4GB core, Intel GPU.