could you post the result of "ceph -s" ? besides the health status there are other details that could help, like the status of your PGs., also the result of "ceph-disk list" would be useful to understand how your disks are organized. For instance with 1 SSD for 7 HDD the SSD could be the bottleneck. >From the outputs you gave us we don't know which are the spinning disks and which is the ssd (looking at the numbers I suspect that sdi is your SSD). we also don't kow what parameters were you using when you've ran the iostat command. Unfortunately it's difficult to help you without knowing more about your system. Kind regards, Laszlo On 24.03.2018 20:19, Sam Huracan wrote: > This is from iostat: > > I'm using Ceph jewel, has no HW error. > Ceph health OK, we've just use 50% total volume. > > > 2018-03-24 22:20 GMT+07:00 <ceph@xxxxxxxxxx <mailto:ceph@xxxxxxxxxx>>: > > I would Check with Tools like atop the utilization of your Disks also. Perhaps something Related in dmesg or dorthin? > > - Mehmet > > Am 24. März 2018 08:17:44 MEZ schrieb Sam Huracan <nowitzki.sammy@xxxxxxxxx <mailto:nowitzki.sammy@xxxxxxxxx>>: > > > Hi guys, > We are running a production OpenStack backend by Ceph. > > At present, we are meeting an issue relating to high iowait in VM, in some MySQL VM, we see sometime IOwait reaches abnormal high peaks which lead to slow queries increase, despite load is stable (we test with script simulate real load), you can see in graph. > https://prnt.sc/ivndni > > MySQL VM are place on Ceph HDD Cluster, with 1 SSD journal for 7 HDD. In this cluster, IOwait on each ceph host is about 20%. > https://prnt.sc/ivne08 > > > Can you guy help me find the root cause of this issue, and how to eliminate this high iowait? > > Thanks in advance. > > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx <mailto:ceph-users@xxxxxxxxxxxxxx> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com <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 _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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