NetApp Quality of Service for Storage
QoS Maximums = introduced in ONTAP 8.2
QOS Minimums = introduced in ONTAP 9.2
Introduced in ONTAP 8.2
QoS Maximums (ceilings) = allows the admin to assign a maximum number
of IOPs or the data rate that can be assigned to a workload. This prevents
specific bullying workloads from starving adjacent workloads when it
spikes. A QoS maximum is a very useful feature to prevent certain bullying
workloads to starve the adjacent workloads. However, this also meant that
until it peaks to its maximum IOPS, it will continue to compete with other
workloads for its IOPS/MBps. Which means, it is still capable of starving the
certain critical adjacent workloads if some of them working aggressively
and consuming their respective maximum available IOPS?
Hence, led to the introduction of - QoS Minimums.
Introduced in ONTAP 9.2
QoS Minimums = When a minimum is associated with a workload, I/O from
that workload is prioritized ahead of other I/O so that it can meet its
performance requirements for the minimum IOPS even though it's not
reached its maximum IOPS.
Working together, minimums and maximums can effectively shape and
prioritize workloads in a shared environment. QoS Minimums are available
in ONTAP 9.2 on SAN objects (volumes and LUNs) on All Flash FAS