[Info-vax] What would be involved in moving RMS into kernel mode ?

[Arne Vajhøj]

On 5/6/2023 12:51 PM, Dave Froble wrote:
> On 5/6/2023 10:43 AM, Arne Vajhøj wrote:
>> On 5/6/2023 6:39 AM, Jan-Erik Söderholm wrote:
>>> About RMS Global Buffers. What files are these usually used for?
>>> I have got an (maybe wrong) impression that it is mostly indexed
>>> files "databases".
>>>
>>> As an example, Rdb is not using RMS for the data/storage. It is
>>> used for some Rdb files like the backup files and "export" files,
>>> but for that I do not see can gain much from faster global buffers...
>>
>> I am far from an expert in RMS (unlike Hein), but my very basic
>> understanding is that global buffers work for both sequential
>> and index-sequential files.
> 
> I believe that is true.
> 
>> But to provide value in the form of better performance then:
>> - the same file need to be accessed by multiple processes
>> - the access need to go through RMS
> 
> Yes.
> 
>> Which may have been a common scenario 35 years ago, but
>> not so much today.
> 
> It's still very common today.

> The CODIS application has one file that just about every process has 
> open.  One would consider such a scenario to benefit from global 
> buffering.  However, DAS (the database product) didn't offer global 
> buffers.  When most of your data is in cache, things can get rather 
> fast.  What was observed was performance quite fast with caching, and a 
> real slog without.

In the IT world in general data access has moved to client
server models and to relational databases.

I believe that even though VMS still got a large number of
older applications running then it has also at least partly
moved.

 > However, global buffers are no longer very helpful.  Why?  Because of
 > the caching added to VMS somewhere around V7 or V8.

>> An indexed-sequential file being updated by multiple
>> processes running some Cobol/Basic/Pascal application
>> designed 35 years ago is probably the most likely
>> combo to match those criteria.
> 
> And caching has satisfied that need.

That is a good point.

XFC (VMS 7.3) may have taken care of a lot of the
caching needs.

Arne