Hello llog interface was redesigned and rebased on top of OSD between Lustre 2.1 and 2.4. This is impacting Changelogs. Now, in 2.4, changelog_catalog and changelog_users file are in root MDT directory. In 2.1, there were in CONFIGS/ MDT directory. Also, the changelog_catalogs were pointing to other files in OBJECTS/ directory. This directory does not exist anymore in Lustre 2.4 I'm not sure were those files are now, maybe in "0". There, filename also have changed. Am I correctly understanding the changes made in this area? Was the file relocation something done in purpose? Anyway, the upgrade case is not handle as a freshly updated MDT will "forget" all the previous changelog users and changelog records. If this is not know, I will open a ticket for that. Aurélien