> And an extra datapoint. > > Booting into 2.6.26.5 triggers an instant resync of the spare disks, so > it means we have a regression between 2.6.26.5 and 2.6.27.4 Likewise, 2.6.26.6 fixed the problem for me. And I can confirm that it's broken in plain 2.6.27. There are 8 commits to drivers/md/raid10.c in that interval. commit 0310fa216decc3ecfab41f327638fa48a81f3735 Allow raid10 resync to happening in larger chunks. commit 1e24b15b267293567a8d752721c7ae63f281325a Merge branch 'for-linus' of git://neil.brown.name/md commit 388667bed591b2359713bb17d5de0cf56e961447 md: raid10: wake up frozen array commit 8a392625b665c676a77c62f8608d10ff430bcb83 Merge branch 'for-linus' of git://neil.brown.name/md commit f233ea5c9e0d8b95e4283bf6a3436b88f6fd3586 md: Make mddev->array_size sector-based. commit cc371e66e340f35eed8dc4651c7c18e754c7fb26 Add bvec_merge_data to handle stacked devices and ->merge_bvec() commit 199050ea1ff2270174ee525b73bc4c3323098897 rationalise return value for ->hot_add_disk method. commit 6c2fce2ef6b4821c21b5c42c7207cb9cf8c87eda Support adding a spare to a live md array with external metadata. It's not obvious which of these is the problem; they mostly look pretty simple and safe, at least as far as raid10 ic concerned. -- 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