>>And I read: >>https://www.mail-archive.com/ceph-users@lists.ceph.com/msg06890.html >> >>Niw don't get me wrong, erring on the side of safety is quite sensible, >>but the impact of having no caching by qemu is in the order of a 2 >>magnitudes easily.
Thanks for link reference ! ----- Mail original ----- De: "Christian Balzer" <ch...@gol.com> À: "Alex Crow" <ac...@integrafin.co.uk> Cc: ceph-users@lists.ceph.com Envoyé: Samedi 12 Avril 2014 17:56:07 Objet: Re: [ceph-users] qemu + rbd block driver with cache=writeback, is live migration safe ? Hello, On Sat, 12 Apr 2014 16:26:40 +0100 Alex Crow wrote: > Hi. > > I've read in many places that you should never use writeback on any kind > of shared storage. Caching is better dealt with on the storage side > anyway as you have hopefully provided resilience there. In fact if your > SAN/NAS is good enough it's supposed to be best to use "none" as the > caching algo. > > If you need caching on the hypervisor side it would probably better to > use something like bcache/dmcache etc. > And I read: https://www.mail-archive.com/ceph-users@lists.ceph.com/msg06890.html Niw don't get me wrong, erring on the side of safety is quite sensible, but the impact of having no caching by qemu is in the order of a 2 magnitudes easily. Beers, Christian > Cheers > > Alex > > > On 12/04/14 16:01, Alexandre DERUMIER wrote: > > Hello, > > > > I known that qemu live migration with disk with cache=writeback are > > not safe with storage like nfs,iscsi... > > > > Is it also true with rbd ? > > > > > > If yes, it is possible to disable manually writeback online with qmp ? > > > > Best Regards, > > > > Alexandre > > _______________________________________________ > > 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 > -- Christian Balzer Network/Systems Engineer ch...@gol.com Global OnLine Japan/Fusion Communications http://www.gol.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
