Hi All, I started a small project related to metrics collection and processing, Ceph was chosen as a storage backend. Decided to use rados directly, to avoid any additional layers. I got a very simple client - it works fine, but performance is very low. Can't get more than 30-35MBsec. Rados bench shows 200MBsec for my test pool. Should be mentioned about the client - I'm using sbcl (yep lisp). Call to rados API is just cffi call. Did try in async mode. Wow ! Saturated network bandwidth for large objects (4Mb and bigger), for small objects - saturated OSD IOPS ~2.4KIOPS for 8 SAS disks, so ~300 IOPS per disk - that sounds pretty reasonable. Bottom line - issue not with the lisp client - im getting close to C performance, difference is sync vs async IO. Why it's so big - sync operations are approx 2-3 times slower then async . Daniel Mezentsev, founder (+1) 604 313 8592. Soleks Data Group. Shaping the clouds.