Re: [PLUG] Backups vs Copies: was Avoid Arvixe at all costs!

[Rich Freeman <r-plug@thefreemanclan.net>]

On Mon, Mar 27, 2017 at 11:56 AM, Lee H. Marzke <lee@marzke.net> wrote:
>
> You need a script such as zrep on top of ZFS to manage the create/destroy of
> these periodic snaps, or that feature is built into the GUI of FreeNAS, Nexenta etc.
>

FWIW I've been using https://github.com/dajhorn/zfs-auto-snapshot/ to do this.

> The ZFS send replication does the same on the far end.  Some scripts allow you to
> keep more or fewer snaps on the destination than the source.

You can also just store the send files without actually receiving them
into a replica, but yes, you need to actually send the snapshots
someplace to really consider it a backup.  Now, the snapshots without
any kind of replication will protect you from accidental file
deletion, but the data is still sitting in the same physical place.
ZFS send (and its btrfs equivalent) basically serialize a snapshot,
either completely or incrementally from another snapshot.  It is going
to be far less expensive in terms our IO/CPU/etc to generate an
incremental send compared to an rsync, since ZFS and btrfs can figure
out what changed without having to actually read all the inodes (which
is what rsync has to do, and zfs/btrfs can also detect changes that
don't touch the mtime on the inode or file size without reading the
file contents).

-- 
Rich
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