Hello To simplify snapshot handling in multiple active mds setup, we changed format of snaprealm in mimic dev. https://github.com/ceph/ceph/pull/16779. The new version mds can handle old format snaprealm in single active setup. It also can convert old format snaprealm to the new format when snaprealm is modified. The problem is that new version mds can not properly handle old format snaprealm in multiple active setup. It may crash when it encounter old format snaprealm. For existing filesystem with snapshots, upgrading mds to mimic seems to be no problem at first glance. But if user later enables multiple active mds, mds may crashes continuously. No easy way to switch back to single acitve mds. I don't have clear idea how to handle this situation. I can think of a few options. 1. Forbid multiple active before all old snapshots are deleted or before all snaprealms are converted to new format. Format conversion requires traversing while whole filesystem tree. Not easy to implement. 2. Ask user to delete all old snapshots before upgrading to mimic, make mds just ignore old format snaprealms. Regards Yan, Zheng -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
