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

[Miles Fidelman]

On 4/18/16 12:48 AM, 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?
> <snip>
>
> 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.
>

Yup.  That was my reaction.  HA starts with either 2 servers and either 
a) mirrored drives (e.g., using DRBD) or b) a HA RAID cluster.

Miles Fidelman