Trying to understand FreeNAS SNMP MIB

[wyang]

I am trying to understand FreeNAS SNMP MIB in order to monitor ZFS statistics

mib file /usr/local/share/snmp/mibs/FREENAS-MIB.txt

Please correct me. To my understanding
For zpool size related statistics, e.g., zpool size in Byte = object(zpoolSize) x object(zpoolAllocationUnits)
Similarly, for dataset size related statistics, e.g., dataset used in Byte = object(datasetUsed) x object(datasetAllocationUnits)

Now, I am trying to understand how to derive ZFS ARC size and zfs L2ARC size in Byte from the objects zfsArcSize and zfsL2ArcSize?

I'd much appreciate if I'd get descriptions and units for the ARC and L2ARC objects. Thank you very much!