A couple of options: Retain the existing on-disk format exactly, but adjust the offsets and sizes used in the reads and writes to avoid the problems (pre-reading other data if necessary to extend a write). Add an option to create version 3 metadata storing the offset in the on-disk header but continue to use version 2 by default. Update userspace code to request version 3 (via new log parameter) for new mirror logs by default, but still permit version 2 for new logs. This way, people committed to existing logs can continue to use them (or schedule the update) and we maintain forwards and backwards compatibility for people that need that. Alasdair -- agk@xxxxxxxxxx -- dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
