"It seems like your RBD can't flush it's I/O fast enough"
implies that there is some particular measure of "fast enough", that is a 
tunable value somewhere.
If my network cards arent blocked, and my OSDs arent blocked...
then doesnt that mean that I can and should "turn that knob" up?

----- Original Message -----
From: "Wido den Hollander" <>
To: "Philip Brown" <>, "ceph-users" <>
Sent: Tuesday, January 14, 2020 12:42:48 AM
Subject: Re: [ceph-users] where does 100% RBD utilization come from?

The util is calculated based on average waits, see:

Just improving performance isn't just turning a knob and it will happen.
It seems like your RBD can't flush it's I/O fast enough and that causes
the iowait to go up.

This can be all kinds of things:

- Network (latency)
- CPU on the OSDs


> --
> Philip Brown| Sr. Linux System Administrator | Medata, Inc. 
> 5 Peters Canyon Rd Suite 250 
> Irvine CA 92606 
> Office 714.918.1310| Fax 714.918.1325 
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