Looks like nearly all useful performance metrics via Performance volume counters have now been deprecated.
Here's a few that are reported by the API output that are deprecated.
Throughput:
<counter-info>
<desc>Note: This counter is deprecated and will be removed in a future release. Bytes read per second from the volume</desc>
<is-deprecated>true</is-deprecated>
<name>read_data</name>
<privilege-level>admin</privilege-level>
<properties>rate</properties>
<unit>b_per_sec</unit>
</counter-info>
Latency:
<counter-info>
<base-counter>read_ops</base-counter>
<desc>Note: This counter is deprecated and will be removed in a future release. Average latency in microseconds for the WAFL filesystem to process read request to the volume; not including request processing or network communication time</desc>
<is-deprecated>true</is-deprecated>
<name>read_latency</name>
<privilege-level>admin</privilege-level>
<properties>average</properties>
<unit>microsec</unit>
</counter-info>
IOPS:
<counter-info>
<desc>Note: This counter is deprecated and will be removed in a future release. Number of reads per second to the volume</desc>
<is-deprecated>true</is-deprecated>
<name>read_ops</name>
<privilege-level>admin</privilege-level>
<properties>rate</properties>
<unit>per_sec</unit>
</counter-info>
Where can this information be pulled from now via the API?