anyone aware of a high availability setup that relies on fully redundant install?

[rpjday@crashcourse.ca (Robert P. J. Day)]

On Mon, 18 Apr 2016, Valdis.Kletnieks at vt.edu wrote:

> On Sun, 17 Apr 2016 10:47:55 -0400, "Robert P. J. Day" said:
> >   i figure this is as good a place as any to ask ... is anyone here
> > aware of anyone using a linux config and install that, for the
> > purposes of reliability or high availability or whatever you want to
> > call it, relies on a second, completely independent installation of
> > linux on the same hard drive?
>
> IBM's AIX has for a long time had the concept of an 'alternate boot
> volume', which can be another logical volume on the same physical
> hard drive.  But it's not intended for high-availability, it's for
> "if this software upgrade goes pear-shaped I have an easy backout
> procedure".  And it avoids most of the "you have to keep two
> version" issues by providing a tool to copy your *current* system
> onto the alternate boot.  I'm sure some Linux distros have stolen
> the concept.

  that makes sense -- a *minimal* bootable system for recovery and
troubleshooting. but not a fully independent previous install.

> Most implementations of "high availability" would see the phrase "on
> the same hard drive" and start pointing and laughing at the single
> point of failure.

  trust me, i'm aware of that. :-) perhaps i shouldn't have used the
phrase "high availability", this proposal was more for just the
ability to back out of a botched or flawed upgrade.

rday

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

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