> Trying to mount a NILFS partition To be pedantic, but it matters, it is "block device" in UNIX-like systems, and more "NILFS2 instance", as here could be multiple NILFS2 instances even in a single block device (but that is a very rare setup usually requiring 'losetup' mounts). > fails with "couldn't mount because of unsupported optional > features (477e7ad1e859f753)". [...] That does not look a lucky situation. You can use 'lscp /dev/...' to list the checkpoints and try to mount an older checkpoint with 'mount -t nilfs2 -o cp=... /dev/... ...' to mount it and resume work from that. In theory older checkpoints will be fully consistent even if the latest one is corrupted. Unless that message means that the NILFS2 instance is corrupted because of "issues" (usually hardware, most common with block devices on USB storage devices).
