IOPS Per RAID Group, ordered by most to least I took part in a podcast last night that discussed the XIV platform. One of the “key features” of XIV is the wide striping of data across all spindles. It’s a concept we’re seeing more and more in contemporary storage hardware architectures and one that’s being shoe-horned into older storage arrays too. Have you ever wondered what the point is? Take a look at the following graphic. It shows the number of write operations per RAID group, ordered by the busiest RAID group to the least active. It’s real data from a real system. What you see is the Long Tail effect, where a small number of RAID groups are doing most of the I/O. In this example, 80% of the workload is performed by 50% of the RAID groups; only 3 RAID groups account for 20% of the workload.
