Subject: Cray Time - Dollar value

From: "DR. LAWRENCE R. SCHMITZ" <[email-masked]>
Date: 29 Nov 1993 20:39:15 -0500 (EST)

I recently received a small grant of Cray C90 time at the
Pittsburgh Supercomputing Center.  The University propaganda
machine requires that I estimate the dollar value of the grant.
Therefore, I would very much appreciate it if those of you that
are familiar with commercial rates for Cray C90 time could
enlighten me.  The grant is given in units of Service Units.
A service unit is define as:

                SU = 0.75*CPU+1/64*MemInt+0.01*Con

where           CPU = CPU hours

                MemInt = a memory integral, in megaword hours.
                The memory integral is calculated by adding
                increments based on changes in the amount of
                memory your program is using: increment = memory
                size * (total time when program was connected to
                at least one CPU since last memory size change)

                Con = connect time hours

For the way I use the Cray, the charges will be almost entirely
based on CPU time.  (For an hour of cpu time, I will use about
12 MB (1.5 megawords) of RAM and perhaps a half hour of connect
time.)  Therefore, a service unit is about 1.3 hours of CPU time.
My question then is:

If you were going to buy about 100 hours of CPU time on a C90,
how much would you expect to pay per hour?

Thanks for any help you can offer!

Sincerely,   Larry Schmitz

PS   In April or May of 92 I asked a similar question about
time on a Cray Y-MP/832.  The rates I was quoted varied widely.
I finally decided that about $600/hour was a fair market value
at that time.  The C90 is faster than the Y-MP/832 but I suspect
that rates have declined.