Favorite operating systems query

[Bill Earl]

>>I think that the main complaints with Unix from VMSites are
>>6) File system.  Why, oh, why, must the Unix file system be so fragile?  VMS
>>   never loses your files.  And it's faster to boot up.
> Except through my own stupidity or catastrophic hardware failure
> (head crashes and RA81 HDA glue problems), I have not lost a file
> for five years.  Fragile?  For that matter, most of our 785 boots ...

     This has been my experience with 4.2 over the last two years
as well (on a 4.2 with a number of the usual bug fixes).  With 
an Emulex controller and three (full) Eagles, full system restart
after a crash was only 15 or 20 minutes.  A reboot which did not
require file system checking (that is, after a clean shutdown) took
only a minute or so.  

>>7) IPC.
> This is indeed a serious problem ...

     I have occasion to use the IPC facilities quite a bit,
and have found them reasonably convenient.  4.2 UNIX-domain sockets
were very buggy, but internet sockets worked fine.  Performance could
be better, but it is at least tolerable at present.  What is
so bad about BSD sockets?

>>8) Robustness.  VMS almost *never* crashes.  Unix crashes all the time.
> It does?  (I would run a `ruptime', but we had a power failure ...

     The (repaired) 4.2 system mentioned above often was up
for two months or more at a time, and then was often shut down
intentionally, not crashed.  The largest single cause of crashes
was power failure, followed by problems with a CDC disk which we
eventually scrapped.  Most of the (few) software crashes were due
to UNIX domain sockets.  This system was fairly heavily used, with
a load average of 6 to 10 for 12 to 16 hours a day.

     At my current location, I have seen VMS (on a MicroVAX II) crash
more than once.  Our Ultrix V1.2 system has been quite stable, with no
software crashes.

     I have also had occasion to work on Tandem systems, however.
For reliability, neither UNIX nor VMS compare at all.  I never lost
a file in four years, and, on systems running released software,
crashes were and are extremely rare, whether due to hardware or
software.  The only significant sources of failure were operator
error (turning off all the disk drives or all the AC power) and
AC power failure.  Since disks were duplicated, drive failures were
of little consequence.  On the other hand, system restart was relatively
slow (in the 15 minute range) and program development facilities
fairly primitive, at least until recently.  Nonetheless, as with
Sequent and ELXSI systems, it is certainly nice to be able to 
spread a large number of compilations over 10 or 15 processors.

	William J. Earl
	American Information Technology, Cupertino, CA
	408-252-8713
	...!decwrl!nsc!voder!lewey!wje
-- 
	William J. Earl
	American Information Technology, Cupertino, CA
	408-252-8713
	...!decwrl!nsc!voder!lewey!wje