What about the system stats on your mons during recovery? If they are having a hard time keeping up with requests during a recovery, I could see that impacting client io. What disks are they running on? CPU? Etc.
On Fri, Feb 22, 2019, 6:01 AM M Ranga Swami Reddy <swamireddy@xxxxxxxxx> wrote:
Debug setting defaults are using..like 1/5 and 0/5 for almost..
Shall I try with 0 for all debug settings?
On Wed, Feb 20, 2019 at 9:17 PM Darius Kasparavičius <daznis@xxxxxxxxx> wrote:
>
> Hello,
>
>
> Check your CPU usage when you are doing those kind of operations. We
> had a similar issue where our CPU monitoring was reporting fine < 40%
> usage, but our load on the nodes was high mid 60-80. If it's possible
> try disabling ht and see the actual cpu usage.
> If you are hitting CPU limits you can try disabling crc on messages.
> ms_nocrc
> ms_crc_data
> ms_crc_header
>
> And setting all your debug messages to 0.
> If you haven't done you can also lower your recovery settings a little.
> osd recovery max active
> osd max backfills
>
> You can also lower your file store threads.
> filestore op threads
>
>
> If you can also switch to bluestore from filestore. This will also
> lower your CPU usage. I'm not sure that this is bluestore that does
> it, but I'm seeing lower cpu usage when moving to bluestore + rocksdb
> compared to filestore + leveldb .
>
>
> On Wed, Feb 20, 2019 at 4:27 PM M Ranga Swami Reddy
> <swamireddy@xxxxxxxxx> wrote:
> >
> > Thats expected from Ceph by design. But in our case, we are using all
> > recommendation like rack failure domain, replication n/w,etc, still
> > face client IO performance issues during one OSD down..
> >
> > On Tue, Feb 19, 2019 at 10:56 PM David Turner <drakonstein@xxxxxxxxx> wrote:
> > >
> > > With a RACK failure domain, you should be able to have an entire rack powered down without noticing any major impact on the clients. I regularly take down OSDs and nodes for maintenance and upgrades without seeing any problems with client IO.
> > >
> > > On Tue, Feb 12, 2019 at 5:01 AM M Ranga Swami Reddy <swamireddy@xxxxxxxxx> wrote:
> > >>
> > >> Hello - I have a couple of questions on ceph cluster stability, even
> > >> we follow all recommendations as below:
> > >> - Having separate replication n/w and data n/w
> > >> - RACK is the failure domain
> > >> - Using SSDs for journals (1:4ratio)
> > >>
> > >> Q1 - If one OSD down, cluster IO down drastically and customer Apps impacted.
> > >> Q2 - what is stability ratio, like with above, is ceph cluster
> > >> workable condition, if one osd down or one node down,etc.
> > >>
> > >> Thanks
> > >> Swami
> > >> _______________________________________________
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> > >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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