topic Re: QoS on file level (cinder - ontap/NFS) in ONTAP Discussions

QoS on file level (cinder - ontap/NFS)

iamsam — Wed, 04 Jun 2025 09:47:20 GMT

Hello

I have cinder pools are backed by ontap NFS exports.
QoS on Cinder volumes is set by Openstack as per :
https://docs.openstack.org/cinder/queens/configuration/block-storage/drivers/netapp-volume-driver.html

The QoS is working fine. Although sometimes the throughput exceeds the limit for few seconds before returning back to normal. I found that during those times the IOPS was too high(> 5000 iops) compared to normal(~ 100).

So, I assume I need to set the proper IOPS, so that volumes not exceed the throughput ceiling.
But I cannot figure out how to calculate this proper IOPS value!
Say, for 100MB/sec maximum throughput, what is the maximum IOPS value I need to set ?

Table below is a sample output of "qos statistics workload performance" command
As you see, for the same IOPS value the throughput is not the same.

Re: QoS on file level (cinder - ontap/NFS)

paul_stejskal — Mon, 10 Jul 2023 12:55:44 GMT

You can set a QoS ceiling policy to either IOPS, bytes/sec, or both. Why not just set it to 100 MB/s or "100iops,100MB/s"?

Re: QoS on file level (cinder - ontap/NFS)

iamsam — Tue, 11 Jul 2023 06:37:00 GMT

Hi Paul, thanks for comment.
With the throughput limit only set, I can see some clients can exceed the limit(for few seconds). During this, I see they are pushing high IOPS. I noticed that when I add IOPS limit in the policy-group, the throughput is not exceeding the limit much like before.

Re: QoS on file level (cinder - ontap/NFS)

paul_stejskal — Tue, 11 Jul 2023 13:17:18 GMT

I'm glad that helped.