> I thought that journalled file systems only had to count on the > disk/raid not re-ordering the writes to avoid filesystem corruption. > That is, is doesn't matter if the writes are cached as long as what > is written is written in the same order as the OS issued the writes. > You just lose the data of anything that did not make it to the disk > but you shouldn't mess up the relationship between free/allocated > space and the inodes using it. Is that impression incorrect? > Journal file systems do not rely on writes not being reordered. They rely on the meta data (directory/inode stuff) being committed to the journal to preserve filesystem integrity. If the meta data was still in the caches whether the raid card cache or the hard disks' cache and not committed to the media, you can expect some directory/inode corruption.