(I apologize to those who are also lustre-discuss members as this is a cross-post) We have been using the following method to maintain a backup MGS/MDS: https://jira.hpdd.intel.com/browse/LUDOC-161 The procedure we follow is commented by Scott and was taken from our own internal documentation. Our method is to create a ZFS file systems: lustre-meta/fsmeta lustre-meta/mgs And then we snapshot (-r), then zfs send (-R)/receive it. To use the backup we swap its IP addresses and name with the primary. If the backup is swapped and used immediately after the snapshot is taken, this method works. If you continue to use the original server before migrating to the backup, it does not work. This is the equivalent of migrating to a not-perfectly-up-to-date snapshot. In the broken case, we can still read files. We cannot create new files. The MDS does show files we attempt to create but their attributes are all unknown. We are unable to manipulate those files (rm, mv, etc) because they do not exist on the OSTs. The error returned is "cannot allocate memory" (see LU-4524). We suspected the configuration logs and so we re-ran writeconf and remounted. Same behavior. We are running lustre 2.4.0 on the servers and have tested with 2.4.0 and 2.1.6 clients. Best, Jesse Stroik University of Wisconsin