I am curious what the kernel parts of ceph do? What the user parts do? Do we have a web page describing this in detail?
>From what you described, in the librbd case, user parts do not need the kernel >parts at all, right? This sounds very good to me. Send from my iOS device. On Jan 20, 2013, at 2:16 AM, Sage Weil <[email protected]> wrote: > On Sat, 19 Jan 2013, Jeff Mitchell wrote: >> Sage Weil wrote: >>> On Sun, 20 Jan 2013, Peter Smith wrote: >>>> Thanks for the reply, Sage and everyone. >>>> >>>> Sage, so I can expect Ceph-rbd works well on Centos 6.3 if I only use >>>> it as the Cinder volume backend because the librbd in QEMU doesn't >>>> make use of kernel client, right? >>> >>> Then the dependency is on the qemu version. I don't remember that off the >>> top of my head, or know what version rhel6 ships. Most people deploying >>> openstack and rbd are using a more modern distro (like ubuntu 12.04). >> >> This discussion has made me curious: I'm using Ganeti to manage VMs, which >> manages the storage using the kernel client and passes in the dev device to >> qemu. >> >> Can you comment on any known performance differences between the two methods >> -- native qemu+librbd creating a block device vs. the kernel client creating >> a >> block device? > > librbd is faster-paced and has more features, including client-side > caching (analogous to the cache in a hard drive), discard, and support for > image cloning. It tends to perform better. > > The kernel client can be combined with FlashCache or something similar, > although that isn't something we've tested. > > We generally recommend the KVM+librbd route, as it is easier to manage the > dependencies, and is well integrated with libvirt. FWIW this is what > OpenStack and CloudStack normally use. > > sage -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
