On 8/12/20 5:14 PM, rhkramer@gmail.com wrote:
I'm getting closer to setting up a consistent backup plan, backing up to an external USB drive. I'm wondering about a reasonable filesystem to use, I think I want to stay in the ext2/3/4 family, and I'm wondering if there is any good reason to use anything beyond ext2? (Some day I'll try ZFS or BTRFS for my "system" filesystems, but don't see any point (and don't want to learn) either of them at this point -- I don't see much need for a backup filesystem.) But, I'll listen to opinions ;-)
Without knowing anything about your resources, needs, expectations, "consistent backup plan", etc., and given the choices ext2, ext3, or ext4 for an external USB drive presumably to store backup repositories, I would also pick ext4.
But, none of the ext* filesystems have bit rot protection. btrfs and ZFS do.
btrfs is supported by the Debian Installer. I used btrfs for Debian system disks for several years. I discovered too late that btrfs requires routine maintenance (to balance its binary trees?). The disks got progressively slower and software started misbehaving. Notably, Thunderbird began losing messages when moving them from an IMAP folder to a local folder (!). I went back to ext4 for my Debian system disks.
Due to GPL and CDDL license conflicts, Debian does not support ZFS OOTB. Notably, the Debian Installer lacks support for ZFS. (Some brave and skilled people have figured out how to install Debian with ZFS on root; STFW for details.) There is a 'contrib' ZFS kernel package available that can be installed on a working Debian system. This makes it possible to use ZFS for most everything except boot and root. ZFS is mature and reliable. I use ZFS for FreeBSD system disks, file server live data, backups, archives, and images. Migrating to ZFS was non-trivial, and I am still wresting with disaster preparedness.
David