Re: Fwd: High IOWait Issue

[ceph@xxxxxxxxxx]

Perhaps unbelanced OSDs?
Could you send us an osd tree Output?

- Mehmet

Am 24. März 2018 19:46:44 MEZ schrieb "david@xxxxxxxxxx" <david@xxxxxxxxxx>:

You have 2 drives at almost 100% util which means they are maxed. So you need more disks or better drives to fix your io issues (SSDs for MySQL is a no brainer really) 

------ Ursprungligt meddelande------

Från: Sam Huracan

Datum: lör 24 mars 2018 19:20

Till: ceph@xxxxxxxxxx;

Kopia: ceph-users@xxxxxxxxxxxxxx;

Ämne:Re: Fwd: High IOWait Issue

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>:

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>:

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.

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