Conclusion

The increase of the preset fio throughput causes an increasing number of memory write operations per second into the page cache.

These in turn increase the amount of time that z/VM needs for relocating the virtual system, because memory pages continue to written by the Linux guest at a higher rate while z/VM performs the live guest relocation.

Page cache file I/O is one factor that influences the relocation times. In the range from 49 to 195 MiB/sec the impact is moderate. With higher I/O rates, around 400 MiB/sec and more, the important quiesce time increased significantly but less than the throughput increases.