>>>>> "Neil" == Neil Brown <neilb@xxxxxxx> writes: >> I can't seem to zero it out: >> >> # mdadm --misc --zero-superblock /dev/hde >> mdadm: Couldn't open /dev/hde for write - not zeroing >> >> Should I just ignore this, or should I break off /dev/hde from the >> array and scrub the disk and then re-add it back in? Neil> You could ignore it - it shouldn't hurt. Ok. Neil> But if you wanted to (and were running a fairly recent kernel) you Neil> could Neil> mdadm --grow --bitmap=internal /dev/md0 Did this. And now I can do mdadm -X /dev/hde1 to examine the bitmap, but I think this totally blows. To create a bitmap, I add it to an md# device, but to examine it, I have to know which sub-devices to query? That's really not what I would expect. I do see that mdadm -q --detail /dev/md0 shows the bitmap status (though not the size or parameters of the bitmap), which is good. Neil> mdadm /dev/md0 --fail /dev/hde1 --remove /dev/hde1 Neil> mdadm --zero-superblock /dev/hde Neil> mdadm /dev/md0 --add /dev/hde1 Worked wonderfully! Cleaned out the old superblock nicely, which I think is a good thing here. Neil> mdadm --grow --bitmap=none /dev/md0 Neil> and it should work with minimal resync... So why would I want to remove the bitmap? The re-sync happened pretty much quickly enough that I didn't even see any non-in-sync status when I did the --add of the device back in. Very very cool... Though... if I was paranoid, I'd disable the bitmap because there's no way to be sure that I didn't write some garbage at a random block N somewhere in the array. Hmm... can't make that guarrentee now either, so it's probably a moot point. In any case, I'm planning on keeping the bitmap. Neil> Though thinking about it - after the first --grow, check that Neil> the unwanted bitmap is still there. It is quite possible that Neil> the internal bitmap will over-write the unwanted superblock Neil> (depending on the exact size and aligment of hde1 compared with Neil> hde). If it is gone, then don't bother with the rest of the Neil> sequence. It was still there after the addition of the bitmap. Thanks Neil! John - 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
