Yesterday afternoon two colleagues kindly helped me to mount the π-Storage in a rack in our server room and to connect it to our fastest server, a DELL R930 with 144 logical cores. This morning I mounted all discs as separate mount points into my project directory /pi. After downloading the latest version of y-cruncher (Version 0.7.1 Build 9465) I collect all the required command line parameters to compute 22 459 157 718 361 decimal digits of π . The final command is:
./y-cruncher custom pi -dec:22459157718361 -C:200b -algorithm:0 -o /pi/result -mode:swap -minIO:256m -swap:raid0 /pi/data1 /pi/data2 /pi/data3 /pi/data4 /pi/data5 /pi/data6 /pi/data7 /pi/data8 /pi/data9 /pi/data10 /pi/data11 /pi/data12 /pi/data13 /pi/data14 /pi/data15 /pi/data16 /pi/data17 /pi/data18 /pi/data19 /pi/data20 > pi.log &
After being interrupted by some meetings, in the afternoon everything is ready to start the computation. 3, 2, 1, let’s go! The official start time is: Fri Jul 29 15:06:20 2016.
August, 2nd: Since I was not in the office yesterday (August 1st is the Swiss National Day), today I get the first estimate on how long the computation will take. From my control screen I get the following information:
On the top left you see the log file of y-cruncher. After three and a half days, already 11% of the series summing are finished. From previous computations I know that the summing makes up about two third of the total time. Including some time for backups and disc replacements, the computation might be finished in about 2-3 months. That’s not too bad, the last records took 94 and 208 days. On the top right, I monitor the disk usage to find good moments for a fast backup. So far, only 200 GBs on each disc are used. On the bottom left you see the disc-IO, which currently shows no activity. The intervals with purely CPU work being done are longer than what I’ve expected. So it was not a bad decision to use our fastest server. On the bottom right I monitor the CPU usage, which at the time of the screenshot was close to its maximum of 14400 per cent.