Measuring egress traffic from GCM VMs to Persistent Disks

[chaitanyabhanda]

Hi, everyone!

I am looking to conduct some measurements on GCP. Specifically, I wish to measure the egress network traffic from GCP VMs to Persistent Disks. To achieve this, I have used network monitoring tools like tcpdump and bmon, but they showed no traces of network traffic from my VMs to Persistent Disks. Additionally, I tried to use perf  (perf record -e probe:inet_sendmsg -aR sleep 60) to trace inet_sendmsg calls, but that didn't yield anything as well.

This is very surprising to me -- I was expecting to see increased network utilization, since Persistent Disks are attached to the VMs as network block devices (as per https://cloud.google.com/compute/docs/disks/persistent-disks-replication).

I was wondering if the kind members of the community could demystify some of this for me.  I would be very grateful for your input on this. 😄