iSCSI random write

In Figure 1 a random-write FIO workload is running against a file system using iSCSI connected devices. The workload is scaled from 1 to 128 jobs running on the KVM guest.The V7000 storage devices are directly attached to the KVM host system via iSCSI.

Throughput increases from 1 to 32 jobs, with a peak at 32 jobs. The CPU peak is also at 32 jobs with consumption of 2 CPUs. The CPU cost with 2 jobs or more increases with the increasing amount jobs, indicated by the decreasing amount of throughput per CPU.