Interactive Response Time
Presently (end November 1993), around two thirds of VXCERN users are still on VXCRNA, with the remainder using the Alpha machines. Measurements of the interactive trivial response time on the Alpha machines as a function of the number of concurrent interactive users show that performance is still very good on each machine at least up to a limit of 70 simultaneous sessions. The Table below () shows the data for the Alpha workstations and for the VAX 9000. The figures given are the average times to complete a series of trivial commands in a dcl script. Data were collected continuously over a period of several weeks. Errors on these data are typically around 10 current configuration, the 9000 is serving the disks to the rest of the Cluster.
We thus expect good response in the right-sized VXCERN cluster for a total of at least 4*70 = 280 interactive users, compared with very poor response on the VAX 9000 with 250 simultaneous users today.