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Re: RAID1 + iSCSI as backup (was Re: More RAID weirdness: external RAID over network)

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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

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Thread

More RAID weirdness: external RAID over network Nicolas George <george@nsup.org> - 2023-03-17 11:10 +0100
  Re: More RAID weirdness: external RAID over network Reco <recoverym4n@enotuniq.net> - 2023-03-17 12:00 +0100
    Re: More RAID weirdness: external RAID over network Nicolas George <george@nsup.org> - 2023-03-17 14:00 +0100
      Re: More RAID weirdness: external RAID over network Reco <recoverym4n@enotuniq.net> - 2023-03-17 15:40 +0100
        Re: More RAID weirdness: external RAID over network Nicolas George <george@nsup.org> - 2023-03-17 15:50 +0100
          Re: More RAID weirdness: external RAID over network Reco <recoverym4n@enotuniq.net> - 2023-03-17 16:20 +0100
            Re: More RAID weirdness: external RAID over network Nicolas George <george@nsup.org> - 2023-03-17 16:30 +0100
              Re: More RAID weirdness: external RAID over network Dan Ritter <dsr@randomstring.org> - 2023-03-17 17:10 +0100
                Re: More RAID weirdness: external RAID over network Nicolas George <george@nsup.org> - 2023-03-17 17:10 +0100
                Re: More RAID weirdness: external RAID over network Tim Woodall <debianuser@woodall.me.uk> - 2023-03-17 18:00 +0100
                Re: More RAID weirdness: external RAID over network Greg Wooledge <greg@wooledge.org> - 2023-03-17 20:10 +0100
                Re: More RAID weirdness: external RAID over network Nicolas George <george@nsup.org> - 2023-03-17 21:50 +0100
                Re: More RAID weirdness: external RAID over network Nicolas George <george@nsup.org> - 2023-03-17 22:00 +0100
                Re: More RAID weirdness: external RAID over network Tim Woodall <debianuser@woodall.me.uk> - 2023-03-17 23:50 +0100
                Re: More RAID weirdness: external RAID over network Nicolas George <george@nsup.org> - 2023-03-20 11:50 +0100
            RAID1 + iSCSI as backup (was Re: More RAID weirdness: external RAID  over network) Gregory Seidman <gsslist+debian@anthropohedron.net> - 2023-03-17 21:00 +0100
              Re: RAID1 + iSCSI as backup (was Re: More RAID weirdness: external  RAID over network) Dan Ritter <dsr@randomstring.org> - 2023-03-17 22:10 +0100
              Re: RAID1 + iSCSI as backup (was Re: More RAID weirdness: external  RAID over network) David Christensen <dpchrist@holgerdanske.com> - 2023-03-18 02:10 +0100
                Re: RAID1 + iSCSI as backup (was Re: More RAID weirdness: external  RAID over network) Gregory Seidman <gsslist+debian@anthropohedron.net> - 2023-03-18 03:30 +0100
                Re: RAID1 + iSCSI as backup (was Re: More RAID weirdness: external  RAID over network) David Christensen <dpchrist@holgerdanske.com> - 2023-03-18 09:10 +0100
                Re: RAID1 + iSCSI as backup (was Re: More RAID weirdness: external  RAID over network) Dan Ritter <dsr@randomstring.org> - 2023-03-19 02:40 +0100

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