The measurements below show the throughputs and IO times for various Random25 loads and PAV configurations when only one volume is used. All the tasks perform synchronous IOs. The number of configured alias devices here is increased from 0 to 3.
The measurements were executed with IT-intensive tasks (as a result, the influence of PAV was possibly higher than in practice with the same number of tasks) and a cache hit rate of 100% (as a result, the influence of PAV was possibly lower than in practice with the same IO rate).
Channels | Vol. | Tasks | Aliases | Random25 | |||||
IO/s | SW time | HW time | Mbyte/s | SW time | HW time | ||||
1 | 1 | 3 | 0 | 4,974 | 0.4 | 0.1 | 221 | 5.9 | 2.0 |
1 | 8,986 | 0.2 | 0.1 | 368 | 3.5 | 2.4 | |||
2 | 12,344 | 0.2 | 0.2 | 483 | 2.6 | 2.6 | |||
3 | 12,352 | 0.2 | 0.2 | 483 | 2.6 | 2.6 | |||
1 | 1 | 8 | 0 | 4,980 | 1.4 | 0.1 | 222 | 16.5 | 2.0 |
1 | 9,379 | 0.7 | 0.1 | 390 | 9.3 | 2.3 | |||
3 | 16,619 | 0.4 | 0.1 | 594 | 6.0 | 3.1 | |||
1 | 1 | 16 | 0 | 4,976 | 3.0 | 0.1 | 221 | 33.4 | 2.0 |
1 | 9,383 | 1.5 | 0.1 | 392 | 18.7 | 2.3 | |||
3 | 16,639 | 0.8 | 0.2 | 596 | 12.2 | 3.1 | |||
2 | 1 | 16 | 0 | 5,673 | 2.6 | 0.1 | 242 | 30.5 | 1.8 |
1 | 11,213 | 1.3 | 0.1 | 478 | 15.3 | 1.9 | |||
2 | 16,536 | 0.8 | 0.1 | 690 | 10.6 | 2.0 | |||
3 | 21,332 | 0.6 | 0.1 | 864 | 8.3 | 2.1 | |||
PAV enables the IO times (software IO times) to be significantly enhanced; the throughput increases accordingly. The increasing hardware IO times are not caused directly by PAV, but are a result of the increased throughputs, and thus of the higher workload of the channel and storage system.