[Semibug] RAID 0 or 1 for OpenBSD

[Josh Grosse]

On Thu, Jul 08, 2021 at 08:20:52PM -0600, Jonathan Drews wrote:

> ... I'm looking for solutions to speed up
> backups with dump (man -s 8 dump).

There are several technologies that could be used to take
a point-in-time and consistent image of data, and then
back up the image while production continues on.  RAID
could be used as a component a solution, but is not
itself a solution.  An example:

1. Quiesce the system(s) using a RAID 1 array.

2. "Split" the RAID 1 array, leaving production on-line
   and a stable, unchanging mirror off-line.

3. Continue production while backing up the off-line 
   half of the array.

4. "Join" the RAID 1 array, rebuilding changes from
   production back onto the returning mirror.

The important things to keep in mind are:

* The checkpoint needs to be consistant to avoid data
  loss.  

* During the "split" and backup, a standard RAID 1 array
  such as used in this example would have no redundancy.