From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nix Subject: Re: Encrypted software RAID1 with Debian Stretch Date: Thu, 14 Sep 2017 14:08:15 +0100 Message-ID: <878thhsa0w.fsf@esperi.org.uk> References: <28c61e8c14f44ec6727b8f3fb3c80c98@riseup.net> <59A92C91.7010508@youngman.org.uk> <87y3pjv6jw.fsf@esperi.org.uk> <3a85ea27-602a-3f5b-3537-d4159a56c2ed@thelounge.net> <87377qvh7t.fsf@esperi.org.uk> <59B95891.9040809@youngman.org.uk> <87r2v9sfkm.fsf@esperi.org.uk> <59BA6FAF.9020501@youngman.org.uk> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <59BA6FAF.9020501@youngman.org.uk> (Wols Lists's message of "Thu, 14 Sep 2017 13:01:51 +0100") Sender: linux-raid-owner@vger.kernel.org To: Wols Lists Cc: linux-raid List-Id: linux-raid.ids 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 :( ) -- NULL && (void)