ITRS Analytics - P99 write latency disk speed must be less than 10ms. A higher performance disk is required.

During a Replicate Pre-flight install process an error message may occur where P99 write latency is reported as too slow. 

Example pre-flight command

sudo ./itrs-analytics install run-preflights --license license.yaml

This means that there is substantial disk latency and that it is likely that the pre-requisites have not been met.  The pre-requisites can be found from the link below. 

docs.itrsgroup.com/docs/obcerv/platform/current/prerequisites/resource-hw-requirements/index.html#micro

A support bundle will contain information which will also points towards disk latency being an issue

Look in the host-collectors, run-host directory for the k0scontroller-logs.txt

The command below can also be run

journalctl -u k0scontroller --no-pager | grep "too long"

Jan 21 09:26:57 myhostname k0s[5768]: time="2025-01-21 09:26:57" level=info msg="{\"level\":\"warn\",\"ts\":\"2025-01-21T09:26:57.025981Z\",\"caller\":\"etcdserver/util.go:170\",\"msg\":\"apply request took too long\",\"took\":\"3.742334451s\",\"expected-duration\":\"100ms\",\"prefix\":\"read-only range \",\"request\":\"key:\\\"/registry/leases/kube-node-lease/k0s-ctrl-myhostname\\\" \",\"response\":\"range_response_count:1 size:511\"}" component=etcd stream=stderr

From the log entry it is clear that latency is an issue - queries should complete in 100ms or less in this instance it is taking over 3 seconds. 

took 3.742334451s

expected-duration 100ms

You need to ensure that SSD Disks are present and that the Disk requirement is strictly observed. 

If you have any further questions:

• Please contact with our Client Services team via the chat service box available in any of our websites or via email to support@itrsgroup.com