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Re: Sync two disks and hot swap

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On 11/08/17 02:49, Dominik George wrote:
> Hi,
> 
> I have the following scenario:
> 
>   * A server with two hard drives in removable cases
>   * A backup process writes data to both disks, making up a live backup server
>   * A third disk is to be kept off-site
>   * On a ergular basis, I want to hot-swap one of the disks, as in, remove
>     one of the two synced disks and replace it with the stale off-site copy,
>     and put the now recent copy off-site
> 
> I figure that a simple software RAID 1 would do the trick, but it is not
> really made for it and would need some complex manual intervention in
> order to not break the state on the removed disk.
> 
> Any ideas on how to achieve this, or arguments that RAID 1 would indeed
> be a good solution?

Are the two drives in RAID (1?) or do they each have their own file system?


I have read articles about building a RAID 1 with three drives, 
migrating in data, pulling one drive and placing it off-site, operating 
in degraded mode on two drives, and then periodically re-installing the 
third drive, resilvering, pulling one drive and placing it off-site, and 
returning to degraded operations on two drives.  But STFW just now, I 
see a lot of posts with titles indicating this is a bad idea.


I have three drives in mobile dock drawers, each with LUKS and ext4. 
One is on-line in my backup server, one is near-site, and one is 
off-site.  Periodically, I put the near-site drive into the backup 
server, rsync the on-line drive to the near-site drive, remove the 
near-site drive, and then swap the near-site and off-site drives. 
Admittedly the wear is uneven, but it's KISS and it works.


But what I really want is some form of snapshot technology (rsync/hard 
link, LVM, btrfs, ZFS) with all the goodies -- realtime compression, 
realtime de-duplication, and encryption.  I need a more powerful backup 
server (many core processor with AES-NI, 16+ GB RAM, SSD caches, etc.).


David

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Thread

Sync two disks and hot swap Dominik George <nik@naturalnet.de> - 2017-11-08 12:00 +0100
  Re: Sync two disks and hot swap Michael Stone <mstone@debian.org> - 2017-11-08 18:10 +0100
    Re: Sync two disks and hot swap Dominik George <nik@naturalnet.de> - 2017-11-08 20:00 +0100
      Re: Sync two disks and hot swap Michael Stone <mstone@debian.org> - 2017-11-08 20:20 +0100
        Re: Sync two disks and hot swap Dominik George <nik@naturalnet.de> - 2017-11-09 10:20 +0100
          Re: Sync two disks and hot swap Michael Stone <mstone@debian.org> - 2017-11-09 13:40 +0100
            Re: Sync two disks and hot swap David Christensen <dpchrist@holgerdanske.com> - 2017-11-09 20:00 +0100
              Re: Sync two disks and hot swap Michael Stone <mstone@debian.org> - 2017-11-09 20:40 +0100
                Re: Sync two disks and hot swap Curt <curty@free.fr> - 2017-11-10 11:00 +0100
                Re: Sync two disks and hot swap Curt <curty@free.fr> - 2017-11-10 11:10 +0100
  Re: Sync two disks and hot swap David Christensen <dpchrist@holgerdanske.com> - 2017-11-09 00:10 +0100
    Re: Sync two disks and hot swap Bob Weber <bobrweber@gmail.com> - 2017-11-09 02:50 +0100
      Re: Sync two disks and hot swap David Christensen <dpchrist@holgerdanske.com> - 2017-11-09 08:10 +0100
        Re: Sync two disks and hot swap Bob Weber <bobrweber@gmail.com> - 2017-11-09 23:50 +0100
          Re: Sync two disks and hot swap David Christensen <dpchrist@holgerdanske.com> - 2017-11-10 00:10 +0100

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