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[Discuss] Linux file systems

I took a VSAM internals class.  It was interesting and super for the day.
It was based on IBMs Virtual Storage Access Method they used to
manage virtual memory, but it expanded and turned into a better alternative
to 'ISAM' Index Storage Access Method that was used for database kinds
of things without going to using a DBMS (data base management system
that were big bulky hunks of software in the day).

Anyway, VSAM was fast and efficient on the mainframes that are less powerful
than your iPhone is today.

I used it basically as an indexed file system to get to fixed or variable
record entries quickly.  It would take care of 'overflow' for you, but you
did have
to re-organize it occasionally (much less than ISAM).  I used it instead of
DBMS systems many time for basically the same purpose.

Yea, the IBMers that pushed VSAM were pretty much speed freak hard core
software types that communicated well with accademia.

On Fri, Mar 28, 2014 at 9:07 AM, Mike Small <smallm at> wrote:

> Jerry Feldman <gaf at> writes:
> > I'm a fan of btree file systems going back to the 1970s. IBM used it on
> > their mainframes (VSAM) back then.
> >
> Funny, I was just reading how Matthew Dillon intends to change from using
> btree in Hammer 1 to something else in Hammer 2:
> (via
> I don't pretend to understand the implications or pretty much anything
> in that design document, just thought you might find it interesting.
> --
> Mike Small
> smallm at
> _______________________________________________
> Discuss mailing list
> Discuss at

><> ... Jack

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