By way of Heise Online comes more detailed information about what's causing some to lose data in systems using the new ext4 file system. The ext4 file system, which is slated to eventually replace ext3 as the default file system of choice in many Linux distributions, can experience significant data loss after system crashes or unclean shutdowns.
Ted Ts'o, Linux Foundation's CTO and maintainer of the ext4 file system, says that the loss is due to how ext4 writes to disk. He says ext4, and newer file systems such as XFS and Btrfs, use delayed allocation. This means that writing data to disk can take up to a minute (compared to ext3's write time of about five seconds). The longer write time improves system performance and organization of data on the hard drive. Ts'o says that the ext4 team is working out a solution, but it's an issue that would benefit from being addressed from all angles.
