Re: JCL, The Design of Design

On 5/1/2024 1:31 PM, Scott Lurndal wrote:

"Stephen Fuld" <SFuld@alumni.cmu.edu.invalid> writes:

John Levine wrote:
>

According to Scott Lurndal <slp53@pacbell.net>:

The worst parts of JCL were "DD" cards, manual track allocation,
and the lack of any form of real filesystem.   PDS do not count.

>
OS had named files (which they called datasets) and a catalog that
said which disk or tape it was on, so you could refer to SYS1.FOOLIB
and it would find it for you.

>
Agreed.  But by "real file system", Scott meant a hierarchical system
such as we are used to today with Windows and Unix,

 I don't consider a partitioned dataset to be a 'filesystem'.

Based on his response, I don't think John does either, and I certainly don't.

Burroughs MCP
had a traditional filesystem (albeit not heirarchical) where the filesystem automatically
handled area allocation for files[*], which were cataloged in a directory;
there was a global disk directory supporting all 100-byte media units
(which provide a pool of disk units from which file areas were allocated;
the pool could be partitioned by operations personnel into 'subsystems'
from which applications or the operator could specify that a given file's areas should be
allocated).

I think OS had essentially that, though you did have to specify more information than on non CKD systems.  Exec 8 had pretty much all of that except only one "pool" per device type, but users could specify that two files were to be placed on the same, or different devices (for performance).  Of course, removable disks were handled individually.

 Disk pack families (one or more packs in a family) had a directory
for the family, and the filesystem allocated space from any unit
in the family for files created on that family.  The pack family
name was the root of the filename (e.g. MASTER/PAYROL, where MASTER
is the family name and PAYROL is a file on that family).

No "families" under Exec, though as I indicated above, the user could force allocation of multiple files to be on the same or different devices, but I think this was rarely used.
--
  - Stephen Fuld
(e-mail address disguised to prevent spam)