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From: root@helios.toronto.edu (Operator)
Newsgroups: news.sysadmin,comp.misc
Subject: Re: computer charge back (long)
Message-ID: <773@helios.toronto.edu>
Date: 17 Apr 89 17:07:41 GMT
References: <885@hawkmoon.MN.ORG> <1989Apr16.020150.1083@utzoo.uucp> <16570@oberon.USC.EDU> <10393@cit-vax.Caltech.Edu>
Reply-To: sysruth@helios.physics.utoronto.ca (Ruth Milner)
Organization: University of Toronto Physics/Astronomy/CITA
Lines: 88

The Computing Consortium here raises all of its operating money through
chargeback, to cover the whole budget (<$250K/yr).  We recently went from 
a simple algorithm based only on CPU time, connect time, and pages printed, 
to a more complicated one which more accurately reflects where our real 
costs are. Actual charging rates on CPU time were cut in half, and we began 
to charge fees for overhead items such as:

   - terminal lines in one's office (we buy the server, install the line, and
     make sure the server keeps working); $150/yr, 
   - a billing group (i.e. the person who gets the bills - intended to cover 
     administrative costs such as running the accounting, totalling all the 
     different items, invoicing and attendant hassles, etc.); $200/yr,
   - an account (creation, quota adjustments, password adjustments, answering
     questions for the user, backup, cleanup after deletion); $50/yr, 
   - administration & serving of a diskless workstation; $500/yr, 
   - locating a system in the main machine room (so that we become responsible
     for shutdown, booting, configuration, and all administration); $5000/yr 
     for server-size systems and microVAXes, 
   - attaching a device such as a printer or disk (covers installation time, 
     software setup, arranging and supervising service when necessary, and 
     the intangibles (to the user) such as taking up a slot in the backplane); 
     $300/yr. 

All of the above are flat annual fees. We also have variable costs, which
depend on usage. These are:

   - CPU time (charged per CPU hour, varies somewhat depending on CPU power
     and priority of the job); interactive priority range is $35/hr to $140/hr,
   - connect time (very low, ~0.15/hour, meant partly to discourage people
     from leaving themselves logged on all the time),
   - tape mounts (VMS only - currently no enforceable way under UNIX to 
     monitor this; intended to cover the substantial time required to make
     sure the drives are in working order, and the service costs), $2 ea.,
   - pages printed; .05/page line printer, .10/page laser/Versatec (private
     printers we don't keep statistics on)
   - pagefaults (used as an indicator of memory usage, and because pagefaulting
     is usually expensive in terms of system overhead); $.03/1000
   - I/O operation (bus usage, interrupts; on VMS the CPU used in servicing
     interrupts is not accounted to the process); $.03/1000

Of the above, CPU usage, pagefaults and I/O are subject to a further reduction
depending on whether a group is a Consortium member with/without own disk, at
U of T but not a Consortium member, or outside U of T (full rate).

The bottom part may sound complicated, but it's easy to do because we have
an accounting program which totals all of this for us and takes all the
various factors such as priority, Consortium membership, etc. into account.
These are the easy things. It's the top group, the flat-rate fees, which
are the real administrative headache. It can be a real pain to keep track
of who has how many terminal lines (especially with graduate students who 
often share lines in an office and may not all have the same supervisor). 
Then you get the people who say "but this user was only here for 9 months,
why should I pay the full $50?" and try to quibble over $12.50 out of a total
bill of several thousand dollars. Annual costs range from the minimum $500 
(for those who really only use the system for electronic mail) to over 
$20,000 for the really high-usage groups (the ones with a dozen accounts,
whose jobs run for days).

I guess, besides giving you an example of what levels some costs are at,
I'm trying to make sure you realise that implementing chargeback will itself
increase your costs and workload. Not to the point where it isn't worth
doing it, but it does take both CPU time and your own time.

Basically, try as much as possible to charge for things that the computer
can keep track of, and for which you have a program to produce totals and
adjust rates depending on the desired total and changes in charges. Where
possible, avoid the items which have to be verified "by hand" (e.g. doing
a survey to see who's using terminal lines; given half a chance, people
will move them) or those which don't easily lend themselves to monitoring
by the computer. Sometimes these can't be avoided, but often they can.

You'll notice we don't charge for disk space (at least not directly; those
who have their own disk are given a reduction on their CPU charge rate).
This is because is can be a major expense to keep track of. Many people's
usage fluctuates greatly over the course of a day, depending what they are
doing, and to take a snapshot of usage a few times a day, and process all
that data, adds up.

My apologies for the length of this posting; but chargeback schemes are
rarely simple if they try to be fair. I hope this gives you some ideas on
what kinds of things might actually be costing the administration money.


-- 
 Ruth Milner          UUCP - {uunet,pyramid}!utai!helios.physics!sysruth
 Systems Manager      BITNET - sysruth@utorphys
 U. of Toronto        INTERNET - sysruth@helios.physics.utoronto.ca
  Physics/Astronomy/CITA Computing Consortium