Hi Sascha, Good article, you might want to add a small section about these two variables osd_agent_max_high_ops osd_agent_max_ops They control how many concurrent flushes happen at the high/low thresholds. Ie you can set the low one to 1 to minimise the impact on client IO. Also the target_max_bytes is calculated on a per PG basis, so the value is divided across PG's. As data distribution is not equal across all PG's you can get into a situation where you are getting cache full warnings, even though the total cache utilisation is below the target_max_bytes, so leave it plenty of headroom. Nick > -----Original Message----- > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of Sascha Vogt > Sent: 02 October 2016 20:59 > To: ceph-users@xxxxxxxxxxxxxx; ceph-devel@xxxxxxxxxxxxxxx > Subject: Blog post about Ceph cache tiers - feedback welcome > > Hi all, > > as it took quite a while until we got our Ceph cache working (and we're still hit but some unexpected things, see the thread Ceph with > cache pool - disk usage / cleanup), I thought it might be good to write a summary of what I (believe) to know up to this point. > > Any feedback, especially corrections is highly welcome! > > http://maybebuggy.de/post/ceph-cache-tier/ > > Greetings > -Sascha- > > PS: Posted to ceph-devel as well, just in case a developer spots some mistakes. > _______________________________________________ > 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
 |