Re: Encrypted software RAID1 with Debian Stretch

[Nix <nix@esperi.org.uk>]

On 14 Sep 2017, Wols Lists uttered the following:

> On 14/09/17 12:08, Nix wrote:
>>> The rule is simple - don't abuse your tools, and btrfs - USED WITHIN ITS
>>> > LIMITATIONS - is a powerful and reliable file system.
>
>> Yeah, but... if you avoid the advanced features, why use btrfs? In
>> particular, why use it *for a backup medium* (where such features are
>> distinctly less useful than on a non-backup medium)?
>
> Because, if you use snapshots and an "in-place rsync" (which overwrites
> the part of files which have changed, rather than replacing the file by
> default), then each snapshot is a full backup, but only uses the space
> of an incremental.

Ah, so it's like bup only immediately accessible without Python and FUSE
installed, and probably less reliable (but hopefully this will change.)
Except it doesn't do full deduplication (if you change a file, it gets
backed up, even if you change it to the same contents as it had before:
yeah, perhaps this is a tad contrived).

> The OP was building a backup server, so all their live data is
> elsewhere, and provided you look after your backups, this will give you
> a very cheap and effective backup system.

Backups based on not-yet-reliable filesystems are, uh, less effective.
(I've lost backups to bad filesystems before due to turning on options
that weren't ready for prime time :( )

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NULL && (void)