Re: big, fast, etc, was is Vax addressing sane today

On Thu, 12 Sep 2024 20:10:43 -0000 (UTC)
John Levine <johnl@taugh.com> wrote:

According to Lawrence D'Oliveiro  <ldo@nz.invalid>:

On Wed, 11 Sep 2024 16:39:23 -0000 (UTC), Brett wrote:
 

Then there is the issue of cheap PC’s that fail, and a mainframes
have a higher level of redundancy and failover. Failed business
transactions can cost millions, more than the machine is worth, so
saving pennies on hardware is stupid. 

>
You solve that by having multiple units of the cheap machines to
achieve the same level of redundancy, or even more. That ends up
being more cost- effective than the mainframe. 

 
That's fine for workloads that work that way.
 
Airline reservation systems historically ran on mainframes because
when they were invented that's all there was (original SABRE ran on
two 7090s) and they are business critical so they need to be very
reliable.
 
About 30 years ago some guys at MIT realized that route and fare
search, which are some of the most demanding things that CRS do, are
easy to parallelize and don't have to be particularly reliable -- if
your search system crashes and restarts and reruns the search and the
result is a couple of seconds late, that's OK. So they started ITA
software which used racks of PC servers running parallel applications
written in Lisp (they were from MIT) and blew away the competition.
 
However, that's just the search part. Actually booking the seats and
selling tickets stays on a mainframe or an Oracle system because
double booking or giving away free tickets would be really bad.
 
There's also a rule of thumb about databases that says one system of
performance 100 is much better than 100 systems of performance 1
because those 100 systems will spend all their time contending for
database locks.
 
 
 
 

How many transactions per minute does world's biggest company need at
peak hours? Is not this number small relatively to capabilities of
even 15 y.o. dual-Xeon server with few dozens of spinning rust disks?