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 length 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 <[email protected]> wrote: > Jerry Feldman <[email protected]> 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: > > http://gitweb.dragonflybsd.org/dragonfly.git/blob_plain/HEAD:/sys/vfs/hammer2/DESIGN > (via http://www.shiningsilence.com/dbsdlog/2014/03/18/13651.html) > > 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 > [email protected] > _______________________________________________ > Discuss mailing list > [email protected] > http://lists.blu.org/mailman/listinfo/discuss > -- ><> ... Jack "Whatever you do, work at it with all your heart"... Colossians 3:23 "If you are not part of the solution, you are part of the precipitate" - Henry J. Tillman "Anyone who has never made a mistake, has never tried anything new." - Albert Einstein "You don't manage people; you manage things. You lead people." - Admiral Grace Hopper, USN "a nanosecond is the time it takes electrons to propigate 11.8 inches" - " - http://youtu.be/JEpsKnWZrJ8 "Life is complex: it has a real part and an imaginary part." - Martin Terma _______________________________________________ Discuss mailing list [email protected] http://lists.blu.org/mailman/listinfo/discuss
