tahoe...System V

Mark Edwards mce at pbsdts.UUCP
Sat Jun 11 16:06:03 AEST 1988


	Pacific Bell runs over 60 tahoe boxes using System V (2.20 release).
I personally spent 4 months working with CCI to fix the X.25 stuff.  Recently
I have fixed the scheduler so it runs smoothly even at load averages in
excess of 100 (try that on the old BSD4.2 scheduler).  Other recent fixes
include disconnect on break defects in the MPCC async code and the
process group leader initialization on the MPCC.

	We have almost 6000 users on the x.25 network...probably a few more
than the BSD crew.

	Other fixes in the works: vdformat.  A rewrite to fix the bad blocking
algorithm.  Currently it relocates all bad blocks to the end of the drive.
That results in large numbers of long head seeks, and grossly degraded
performance.  A good work-around is to place your most heavily accessed
filesystems as close to the end of the disk as possible.  I just did that with
a disk, and dropped it from 85% busy to 2% busy.  It helped the queueing on
the other two drives on that controller as well.

	Some time in the next few weeks we will begin testing the 2.21 release
with PDN-7000, Net-7000, and our latest database code.  The PDN-7000 is a new
1984 release (we are running a 1980 flavor now).  I plan to run that stuff
through the ringer before it lands on our production X.25 networks.

	The machine has some idiosynchrasies when porting existing packages.
It appears to be "System V" everywhere but the directories...they are BSD.
If a port doesn't seem to be working right, check all the directory access
sections.  That's where most of the ports fail.  The port of netnews requires
a bit of hacking to make the directory handling code work.  Expire is the most
severely affected part.  Make sure you port the dbm feature....it really helps.

	UNISYS and CCI have both been quite pleasant an cooperative in
supporting the machine.  We have been a beta test site of sorts for much
of the Sys V code (x.25 especially).  Note we are note THE official site,
but we have been feeding back bug reports and fixes at a reasonable clip.
UNISYS and CCI have been listening and fixing.  Hopefully the rest of you
will start seeing some of the fruits of our experience soon.


Mark Edwards
Staff Analyst
Pacific Bell

mce at pbsdts.pacbell.com



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