Hi Mickaël, I was wondering the same. When i was reading the Wiki, i found: http://ceph.newdream.net/wiki/Librados "Each pool also has a few parameters that define how the object is stored, namely a replication level (2x, 3x, etc.) and a mapping rule describing how replicas should be distributed across the storage cluster (e.g., each replica in a separate rack)." So there should be a possibility, but i haven't found any configuration references. -- Met vriendelijke groet, Wido den Hollander Hoofd Systeembeheer / CSO Telefoon Support Nederland: 0900 9633 (45 cpm) Telefoon Support België: 0900 70312 (45 cpm) Telefoon Direct: (+31) (0)20 50 60 104 Fax: +31 (0)20 50 60 111 E-mail: support@xxxxxxxxxxxx Website: http://www.pcextreme.nl Kennisbank: http://support.pcextreme.nl/ Netwerkstatus: http://nmc.pcextreme.nl On Tue, 2010-05-04 at 12:18 +0000, Mickaël Canévet wrote: > Hi, > > I'm testing ceph on 4 old servers. > > As there is more then one disk per server available for data (2 with 6 > disks and 2 with 10 disks for a total of 32 disks over 4 nodes), I was > wondering how to define OSDs. > > I have choice between one OSD per disk (32 OSDs on the cluster) or one > OSD per server with one btrfs filesystem over all disks of the server (4 > OSDs on the cluster). Which one is the best solution ? > > In the first case, if I lose one disk, I lose only a small part of > available space. In the other case, if I lose one disk, I lose the whole > server (as btrfs filesystem is in stripping) much more space. > > On the other hand, if I lose the whole server in the first case, I can > lose all replicates of a data because they may be on two different OSD > on the same server. > > Is there a way to define OSD groups so that we can be sure that 2 > replicates are not on OSDs of the same group (could be usefull for > multiple OSDs per server, but also mutliple server per computing room - > if I lose one whole room, a lot of server, I will be sure that I have > not lost every replicates). > > Thanks a lot. > Mickaël > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
