IBM 610 workstation computer 3435

when we started project for ha-cmp product ...

i created a cluster taxonomy around

* mode1 ... 1+1 fail-over (2nd processor idle) * mode2 ... 1+1 mutual fall-over .. both processors running but 2nd, fail-over processor running non-critical apps * mode3 ... 2 ... i.e. concurrent operation running shared workload and concurrent access to shared disks. this required something more akin to mainframe loosely-coupled or vax-cluster concurrent disk access support.

from there we expanded from 2 to N ... where there could be N+1 ... spare processor could stand-in for any single failed processor (some years later found some other vendors using similar language in some of their marketing brochures).

this is more akin to raid for disk reliability ... aka simple mirroring has fully replicated disks ... but you have have raid5 something like 8+1 ... eight data disks, plus a parity disk ... where any single disk failure and keep running with the remaining.

there are also some similarities to the resource consumption discussed in background batch ... i.e. applications soaking up resources not needed by other processors (and possibly lack any significant time-critical requirements).

note that with software becoming more & more the primary failure cause ... parbreastioned, non-shared memory provides an extra level of fault isolation ... that may be compromised in shared-memory-smp configurations.

and, of course, shared-memory is very conducive for geographic separation implementations.

for a little topic drift ... my wife did a stint in pok where she was responsible for (mainframe) loosely-coupled (cluster) architecture ... where she created peer-coupled shared data architecture ...

and geographically dispersed parallel sysplex (geoplex):

and current ha-cmp web page

which even mentions various remote site backup implementations

this mentions ha-cmp enhanced scalability

... which somewhat got side-tracked ... because we were doing scale-up as part of the original ha-cmp effort ... minor ref

as mentioned in the above, we sort of got our hands slapped and told we couldn't work on anything with more than four processors.

for more drift, when we started hsdt (high-speed data transport) project

... one of the things were some high-speed satellite links (pilot stuff we had dedicate transponder on sbs-4) and got involved with designing fault tolerant tdma earth stations (requirements more akin to telco-CO switching hardware ... had hot-pluggable boards ... could do real-time removal and re-insertion of processor and communication boards in the rack). unsubstantiated ... but one of the vendors building a set of tdma earth stations to our "spec" ... claimed to have been approached (by some other organization) to build a duplicate of earth stations to our same specification (a little industrial espionage?)

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