[Info-vax] What does VMS get used for, these days?

[Arne Vajhøj]

On 10/24/2022 9:10 PM, Dave Froble wrote:
> On 10/24/2022 7:30 PM, Arne Vajhøj wrote:
>> On 10/24/2022 6:56 PM, Bill Gunshannon wrote:
>>> On 10/24/22 16:42, Arne Vajhøj wrote:
>>>> It may make sense to pay for a custom solution tailored for
>>>> specific needs.
>>>
>>> Sites like the University already had this.  Developed over many
>>> years and lots of man hours.
>>>
>>>> It may make sense to go for a standard solution and use it
>>>> the standard way.
>>>
>>> Why would that make sense if you already had (and had paid for)
>>> the working solution your going to replace?
>>
>> The model where you pay X to develop an application
>> and you use that for decades for zero annual cost
>> is not a common model.
> 
> I'd agree with that.  Things change.  The apps must reflect the changes.
> 
>> A way more common model is to pay X to develop an application
>> and then every year pay Y to maintain and enhance the application
>> to meet new requirements.

 >>>> That sort of defies the point of the standard solution.
 >>>
 >>> The big question is why even consider a "standard solution" if you
 >>> already had a perfectly functioning system specific to your 
environment?
 >>
 >> A perfectly functioning system for yesterdays requirements
 >> not for tomorrows.
 >
 > NO, a perfectly functioning system for the past, today, and easily
 > modified for tomorrow, if that becomes necessary.  Nothing stays the
 > same, one advances or regresses.

Yes.

Maintenance stops the day the system is shut down for good.

>> With Y being 10-30% of X. Over the life cycle of the application
>> the maintenance cost are way higher than the initial development.
> 
> Now which side of your ass did you pull those numbers?  10-30% is 
> ridiculous.

Pick your choice from:

1) Picking a random number 1..50, add current wind speed and deduct
    the date.

2) Barry Boehm in 1983 created a software maintenance model
    and the example he used was 700 person month development and
    140 person month annual maintenance. 20% widened to 10-30%
    to cover variations seems reasonable.

3) The most estimated metric is percentage of software total
    life cycle cost attributed to maintenance. Numbers vary quite a
    bit but 50%, 67%, 75%, 80% and 90% are common. If we assume an
    average lifespan of 20 years we get 5%, 10%, 15%, 20% and 45%.
    Which one could narrow to 10-30% by assuming that the most
    extreme values are rare.

>> Reducing that maintenance cost can make sense.
> 
> In any reasonable situation, that never makes any sense.  Any total 
> replacement will cost way more than anything else, and probably cause 
> all kinds of business problems.

Businesses are always interested in reducing cost.

Not all initiatives promising to do so actually deliver
on the promise.

Arne