> I think I understand the use case now. One question though: Do > we really need to write the bitmap data at "mdadm --create" time? > Can we instead wait until the array is assembled by the kernel? > > Thanks, > Song Thanks for reply. This is kinda what happens already. Most of bitmap is populated with valid data during first time kernel assembles the array. BUT unless there is at least some basic structure present in bitmap superblock (magic and geometry), the kernel will completely ignore the reference to bitmap in the md superblock. So does the mdadm when examining the array. There seems to be some sanity check and i honestly think it's not a bad thing. It just prevents kernel from overwriting data at some random offset, if the bitmap offset field ever gets corrupted for some reason... Tom
