On Wednesday 2021-04-14 20:53, peter.clark@ngic.com wrote:
That said, I would assume the wipefs command was used because it issues a BLKRRPART ioctl which presumably would eliminate the need for the additional reboot to pick up partition table changes.
BLKRRPART can be issued with `blockdev --rereadpt`. You do not need to wipe a disk fully and repeatedly just for that ioctl. But the point is: if /dev/sda3 is currently mounted as per my howto, reloading /dev/sda after adjusting the table will return EBUSY. Hence the reboot. (Else you'd have to switch to a magic tmpfs.. all complicated and not worth pursuing time-wise.)
when they are in a state where a full suite of tools is unavailable, the first impulse is usually to use what is most likely to be portable, present and understood well enough that unexpected behavior isn't encountered while working against the clock of an SLA during an outage.
Well this is exactly the argument _for_ using ddrescue: not having to figure out bs=, skip= and seek= crap under pressure, and actually getting a time estimate on how long the operation will take (at least for larger transfers).
Speaking of which, would you happen to be aware of anything that would prevent this procedure from converting some systems from btrfs root to XFS root on SLES 12?
Why prevent? Switching filesystem does not happen automatically, you have to really work towards it.