Test metrics
The performance of live guest relocations was evaluated using the metrics outlined in this section.
- Relocation time
- The elapsed time of the complete relocation process
- Quiesce time
- The elapsed time while the relocated system is quiesced; during this time, the guest virtual system is prevented from performing any work. The quiesce time is the most prominent metric when evaluating the quality of the guest relocation process
- Number of memory passes
- The number of passes that z/VM® performs over the virtual memory of a guest virtual machine during a live guest relocation. Because the guest virtual machine continues its work while the live guest relocation is performed, that work may cause changes of memory content that was already transferred in a previous pass. Consequently, the modified memory content must be transferred in another memory pass.
- Amount of memory transferred during the quiesce time
- The amount of memory that was transferred while the guest virtual machine was quiesced.
- z/VM CPU usage
- The relative percentage of CPU used by z/VM while performing a live guest relocation.
The performance of ISFC logical links was evaluated through the following parameters:
- ISFC logical link peak write data rate
- The maximum write data rate observed during a monitor interval during the live guest relocation.
- FCTC connection I/O rate
- The number of I/O requests per second [SSCH/s] that were performed
by the FCTC device. Note: The amount of data transferred per I/O request is not known.
- FCTC device busy rate
- Percent of elapsed time during which the device was busy with an I/O operation.
The performance of the Linux™ guest virtual system was evaluated through the following parameters:
- steal time percentage
- Percentage of time spent in involuntary wait by the virtual CPU or CPUs while the hypervisor was doing something else, such as servicing another virtual processor or performing a live guest relocation.