Re: Log file for CM

["David M. Malon" <malon@anl.gov>]

>
>  Luis Bernardo wrote:
>  >
>  > I evaluated the total transfer rate as a function of the time during the 6
>  > hours the tests ran (around 23000 seconds). The total transfer rate is the
>  > sum of the individual transfer rates at any given time (approximately).
>  > A plot of the transfer rate is include in the .pdf file I attach. As one
>  > can see when things go "well" we get a transfer rate around 3 MB/sec but
>  > most of the time things don't go well...
>  >
>  > Luis
>
>  Arie wrote:  It looks more like 6 MB/sec at the peak.
> 

   The highs (and some nonzero lows) may be artifacts of the rate-summing
   method.  I am not sure of the method that Luis is using.

   Suppose Joe and Bob each issue a request for a different 10-MB file at
   time 0.  Suppose HPSS immediately services Joe's request, and delivers his 
   file in 10 seconds, while Bob's request simply waits.  Next, Bob's file is
   delivered during the following 10 seconds.  The system delivers data at the
   constant rate of 1 MB/second for 20 seconds, but the rate summing method
   makes things look different.  Because Joe's request was issued at time 0 and
   completed at time 10, Joe sees a rate of 10 MB/10 seconds = 1 MB/second.
   Because Bobs's request was issued at time 0 and completed at time 20, Bob 
   sees a rate of 10 MB/20 seconds = 0.5 MB/second.  If you sum the rates, it
   looks as though the system is delivering 1.5 MB/second in the interval
   [0, 10) and 0.5 MB/second in the interval [10, 20).  (You can only 
   believe the integral of the rates.)

   David Malon