2 Sep
2018
2 Sep
'18
10:25 a.m.
While the best loved feature is probably the pervasive dynamic linking, which is still
unrivaled, and the security features (ring brackets, AIM (multilevel labeling), and ACLs)
which are the most famous, a feature that isn't built in to Unix and is constantly
being reinvented that was available in Multics is the ability to easily set aside a CPU
and some memory and disk, while leaving the system in operation, and start another
separate instance to do development work, and then when the work is done, be reconfigured
to merge the system back into one instance, without disrupting production work.
That dynamic reconfiguration was one original design specifications of the system, as
opposed to being added later. Much of what makes Multics wonderful to me is just how
amazingly sturdily it's engineered and how complete the implementations of these
ideas are.
Another thing to comes to mind immediately is how hierarchical the system is. For example,
users are registered on to projects, and a project administrator can be delegated the task
of registering and deregistering user accounts and managing the system resources such as
disk quota and access to printers and other physical resources for their project.
The system administrator can manage the resources assigned to projects, and the project
administration handles how that's further carved up amongst the users.
You can have similar granularity in assigning the distribution of resources such as CPU
and memory use, by using the workload management features to ensure that high priority
tasks/users/projects will always have needed resources available, preempting lower
priority tasks if necessary.
The I/O system, (while not exceedingly elegant - see iox_), far exceeds what is available
in Unix today, but by design.
The reputation of Multics as a 'complex' system is, in my experience, well
deserved, but that complexity does not mean it's a terrible system to use or
administer. I find it quite refreshing and it almost never feels dated.
-- Jeff
https://ban.ai/multics
On Sep 2, 2018, at 12:05 AM, Will Senn
<will.senn(a)gmail.com> wrote:
On Sep 1, 2018, at 6:25 PM, Noel Chiappa <jnc(a)mercury.lcs.mit.edu> wrote:
Noel, Fascinating read. I must’ve read at least a good handful of the references leading
to the myths described in the writeup. As usual, I can trust the folks who lived history
to remember it more clearly than many revisionists writing about it later.
Thanks for sharing.
Now, I’m wondering what awesome features Multics had that we’re still lacking in modern
*nices... anything as amazing as say, my favorite filesystem, ZFS?
Will
From:
Will Senn
I was thinking that Multics was a failed
predecessor of unix
... straighten me out :)
I'd start with:
https://multicians.org/myths.html