Mostly trivia, but might help someone one day... True that raid0 is basically for data you don't care about, if any drive in the array dies, you lose everything. Except on Btrfs...
If the metadata profile is raid1 (or raid1c34), you will still lose all the data on the failed drive. But you will be able to mount the remaining drive(s) using `mount -o ro,degraded` due to the raid1 metadata profile. The file system itself is not striped, but mirrored (two copies for raid1 no matter how many drives). You can't mount it read-write because it's below the minimum number of drives due to raid0 data. If you copy the files out, you'll have quite a mess because obviously most files are missing or damaged (swiss cheese). You'll need a tool that tolerates I/O errors, by continuing to read the rest of the file rather than giving up on the first I/O error. ddrescue does this (it works on block devices or files, in this case you'd use it on files). The mkfs time default profile for metadata is raid1 if you include 2 or more disks in the mkfs command. Otherwise you get DUP profile for metadata and single profile for data. If you add a second drive to a single drive Btrfs, you need to manually convert, e.g. `btrfs balance start -mconvert=raid1 -dconvert=raid0` This same behavior happens with an e.g. 2-disk Btrfs with single profile data, and raid1 profile metadata. You can mount it ro,degraded, and get the files off the surviving drives. In this case, you'll get both more completely lost files and more completely intact files because single profile doesn't stripe data. -- Chris Murphy _______________________________________________ users mailing list -- users@lists.fedoraproject.org To unsubscribe send an email to users-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
