Ron,
Thanks for clearing up how the current drives actually work. It just seems
like IBM could get away from the track and cylinder stuff, which
artificially restricts the amount of storage you use. If you use short
blocksizes, or long ones that just go over 1/2 track, you waste an awfull
lot of space. Of course, well written SMS routines can correct that, but it
still makes things a lot more complicated than it should be.
Eric
Eric Bielefeld
Sr. Systems Programmer
Milwaukee, Wisconsin
414-475-7434
----- Original Message -----
From: "Ron Hawkins" <[email protected]>
Newsgroups: bit.listserv.ibm-main
To: <[email protected]>
Sent: Tuesday, March 31, 2009 10:31 AM
Subject: Re: "A foolish consistancy" or "3390 cyl/track architecture"
Perhaps there is more to the emulation of CKD than the thread touches on.
Disk Drives stopped recording in CYLS some time ago because the time for
head switching is greater than the minimum seek time. Drives today record
in
a serpentine method across the platters, doing a switch-back (best word I
can think of) to the next head at intervals defined by the HDD designers.
The whole idea of tracks and CYLS is really dead and buried as far as the
real hardware is concerned.
Ron
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