On 12/02/2013 03:26 PM, Bill Eldridge wrote:
Hi all, We're looking at using Ceph's copy-on-write for a ton of users' replicated cloud image environments, and are wondering how efficient Ceph is for adding user data to base images - is data added in normal 4kB or 64kB sizes, or can you specify block size for volumes (so you can have video partitions with large content and email/chat/web cache partitions with small files)
Copy-on-write is currently implemented at object granularity. Object size is determined when you create an rbd image, and defaults to 4MB.
Is Ceph's behavior & configuration for copy-on-write documented well somewhere?
For a detailed description of the current copy-on-write implementation see [1]. You may also be interested in rbd's striping configuration, which uses the same parameters as cephfs [2].
Josh [1] http://ceph.com/docs/master/dev/rbd-layering/ [2] http://ceph.com/docs/master/dev/file-striping/ _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
