[Discuss] SSD

[jack at coats.org (Jack Coats)]

>>
> Sounds like you used VM370. With IBM VM370 using a OS/VS1 guest, there
> were several interesting options. I found that disabling paging on
> OS/VS1 gave me much better performance. Another thing was print

OS/VS2 solved some of those issues and enhanced paging and swapping greatly.

> spooling. IBM OS/VS1 had a terrible spooling algorithm, and VM370 worked
> much better (with a few custom patches). This was crazy because it was
> double spooling.

I worked with one of the developers of HASP at NASA... basically kept IBM from
being kicked out of NASA and saved the corporate bacon. ... When at Amoco,
we had a project to back out the over 16,000 documented patches from VM when
IBM started closing down their assembler source (they still provided the SPL but
no compiler :)

Some IBM mainframes had firmware assist for
> VM370/OS/VS1.

I though it was interesting finding a terminal (3270 style) built INSIDE some of
the 3xxx generation mainframes.  Looking over the IBM SEs shoulder, we were
able to help them with the VM commands when they had problems (but that was
very seldom).  The single chip mainframe was a reality then, but it was still
chilled water cooled and took LOTS of power in the day.

There were some other interesting tricks. Our software had
> been migrated from Burroughs MCP that had dynamic drive allocation. When
> a job needed a tape drive it requested it. On IBM's OS/VS1 this was not
> possible. Tape drives for a job step had to be allocated upon initiation
> of the job step. What we did on VM370 was to allocate more logical
> drives than physical, so for instance, if we needed 6 tapes during a job
> step, we allocated 6 drives, then when a program opened a tape, the
> operator could simply reassign.

At Amoco they wrote their own tape library system.  When we "decoupled" TLS
from our internals modifications it was harder to use.  But except for reading
seismic data and doing backups we had little tape use (but seismic lines
would run hundreds of tapes for a single line)

i have to admit when our data center was closed down, I made a 'last walk' down
the length of the mainframe computer room.  So much time, so much effort,
so much money, so many missed times with the family for the 'corporate good'. :(

Moved on to Unix (solaris at the time), helped build data centers for other
companies.  Still hard work, but I missed (and still miss) the mainframes.
They were my 'techno babies'.

>
> --
> Jerry Feldman <gaf at blu.org>
> Boston Linux and Unix
> PGP key id:3BC1EB90
> PGP Key fingerprint: 49E2 C52A FC5A A31F 8D66 ?C0AF 7CEA 30FC 3BC1 EB90
>
>

I'm basically retire, but I need to go do something useful for a while ...
Thanks for the walk down memory lane.