On 3/17/23 12:36, Gregory Seidman wrote:
On Fri, Mar 17, 2023 at 06:00:46PM +0300, Reco wrote:
[...]
PS There's that old saying, "RAID is not a substitute for a backup".
What you're trying to do sounds suspiciously similar to an old "RAID
split-mirror" backup technique. Just saying.
This thread has piqued my interest, because I have been lax in doing proper
backups. I currently run a RAID1 mirroring across three disks (plus a hot
spare). On top of that is LUKS, and on top of that is LVM. I keep meaning
to manually fail a disk then store it in a safe deposit box or something as
a backup, but I have not gotten around to it.
It sounds to me like adding an iSCSI volume (e.g. from AWS) to the RAID as
an additional mirror would be a way to produce the off-site backup I want
(and LUKS means I am not concerned about encryption in transit). It also
sounds like you're saying this is not a good backup approach. Ignoring
cost, what am I missing?
Reco
--Gregory
I would not consider using a cloud device as a RAID member -- that
sounds both slow and brittle. Live data needs to be on local hardware.
I have considered putting an encrypted filesystem on top of a cloud
volume -- but, that sounds brittle; both for live data and for backups.
I have put encrypted tarballs in cloud filesystems (e.g. archives) --
KISS; I like it.
On 3/17/23 13:52, Dan Ritter wrote:
> Three different things:
>
> resiliency in the face of storage failure: RAID.
>
> restoration of files that were recently deleted: snapshots.
>
> complete restoration of a filesystem: backup.
>
> (and technically, a fourth: complete restoration of points in
> time: archives).
>
> You can combine the approaches, but they can only be substituted
> in particular directions. A RAID alone doesn't give you
> protection against deleted files (or deleted filesystems), which
> is what a backup is for.
>
> -dsr-
+1
I would add:
* ECC memory.
* Check-summing filesystems (I prefer ZFS-on-Linux).
* Multiple backup media in rotation.
* Another computer for taking backups, doing restores, etc..
With four disks, the OP could use two in a ZFS mirror for live data, use
zfs-auto-snapshot for user-friendly recovery, and use the other two
individually as on-site and off-site backup media.
David
