While the power is still running, and the disk is spinning and working perfectly, EXT4 has *already* stored information on it that says the file that the atomic rename() went to is empty. The disk is in the wrong state! It is irrelevant whether a power failure may further damage the data!
Posted Sep 12, 2009 6:22 UTC (Sat) by ncm (subscriber, #165)
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You rather miss the point. Given reliable storage -- i.e., doesn't lie about what's reached disk, or has enough battery backup to make sure it gets there, eventually -- it's possible to write a reliable file system. Without, it doesn't matter how well done the file system is, a power drop can corrupt it. If you want safety against power drops, you need both.