Also.. "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" <wido@xxxxxxxx> To: "Philip Brown" <pbrown@xxxxxxxxxx>, "ceph-users" <ceph-users@xxxxxxxxxxxxxx> Sent: Tuesday, January 14, 2020 12:42:48 AM Subject: Re: where does 100% RBD utilization come from? The util is calculated based on average waits, see: https://coderwall.com/p/utc42q/understanding-iostat 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 Wido > > > -- > 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 > pbrown@xxxxxxxxxx| www.medata.com > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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