I'm comparing my volumes avg total ops vs controller avg total ops(output below highlighted) , there's nothing else on my controller no snapmirror or any other jobs running but my controller's IOPS is almost twice my volumes . If there's nothing else running on the controller the total ops output should be the same or at least close for both . Please help me understand why its different and whay am I missing.
from the first command my average total ops = 9778 (stats running for a controller )
from the second command my average total ops = 5193 (stats running for a volume )
Besides serving operating system functions for Data ONTAP, the memory in a NetApp controller also acts as a cache. Incoming writes are coalesced in main memory prior to being written to disk. Memory is also used as a read cache to provide extremely fast access time to recently read data.
Next, consider how data is written to the storage system. For most storage systems, writes must be placed into a persistent and stable location prior to acknowledging to the client or host that the write was successful. Waiting for the storage system to write an operation to disk for every write could introduce significant latency.
To solve this problem, NetApp storage systems use battery-backed RAM to create nonvolatile RAM (NVRAM) to log incoming writes. When controllers are in highly available pairs, half of the NVRAM is used to mirror the remote partner node’s log, while the other half is used for logging local writes.