On Sat, 11 Mar 2006, Ming Zhang wrote: > On Sat, 2006-03-11 at 16:15 -0800, dean gaudet wrote: > > > you're planning to do this while the array is online? that's not safe... > > unless it's a read-only array... > > what i plan to do is to pull out the disk (which is ok now but going to > die), so raid5 will degrade with 1 disk fail and no spare disk here, > then do ddresue to a new disk which will have same uuid and everything, > then put it back, then bitmap will shine here right? > > so raid5 is still online while that disk is not part of raid5 now. and > no diskio on it at all. so do not think i need an atomic operation here. if you fail the disk from the array, or boot without the failing disk, then the event counter in the other superblocks will be updated... and the removed/failed disk will no longer be considered an up to date component... so after doing the ddrescue you'd need to reassemble the raid5. i'm not sure you can convince md to use the bitmap in this case -- i'm just not familiar enough with it. > this raid5 over raid1 way sounds interesting. worthy trying. let us know how it goes :) i've considered doing this a few times myself... but i've been too conservative and just taken the system down to single user to do the ddrescue with the raid offline entirely. -dean - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
