> -----Original Message----- > From: ceph-users [mailto:ceph-users-boun...@lists.ceph.com] On Behalf Of > William Josefsson > Sent: 14 November 2016 14:46 > To: Nick Fisk <n...@fisk.me.uk> > Cc: Ceph Users <ceph-users@lists.ceph.com> > Subject: Re: [ceph-users] Ceph Blog Articles > > Hi Nick, I found the graph very useful explaining the concept. thx for > sharing. > > I'm currently planning to setup a new cluster and wanted to get low latency > by using, > > 2U server, > 6xIntel P3700 400GB for journal and > 18x1.8TB Hitachi Spinning 10k SAS. My OSD:Journal ratio would be 3:1.
I've found that with NVME you can probably stretch the OSD to Journal ratio. However lower ratios will help performance. > All over 10Gbit copper network. For CPU I'm thinking of E5-2667v4 (Single > socket, 8 cores, 3.2Ghz) Replica size=3, and 5 hosts. > > Do you think it is possible to get a low direct sync write latency 3-5ms-avg > with a configuration like this, or would the spinning drives > actually slow down this whole design? thx will I would imagine that should be achievable, but of course depends on IO size and queue depth. But 4kb QD=1 should be easily do-able. If you can give an IO example I'm happy to run a fio test on my cluster. Nick > > > > > On Sat, Nov 12, 2016 at 3:33 AM, Nick Fisk <n...@fisk.me.uk> wrote: > > Hi All, > > > > I've recently put together some articles around some of the performance > > testing I have been doing. > > > > The first explores the high level theory behind latency in a Ceph > > infrastructure and what we have managed to achieve. > > > > http://www.sys-pro.co.uk/ceph-write-latency/ > > > > The second explores some of results we got from trying to work out how much > > CPU a Ceph IO uses. > > > > http://www.sys-pro.co.uk/how-many-mhz-does-a-ceph-io-need/ > > > > I hope they are of interest to someone. > > > > I'm currently working on a couple more explaining the choices behind > > the hardware that got us 700us write latency and what we finally built. > > > > Nick > > > > _______________________________________________ > > ceph-users mailing list > > ceph-users@lists.ceph.com > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
