Hi, On Wed, 2011-05-04 at 17:37 +0800, tsk wrote: > Hi folks, > > > May I know that, if there is 6 harddisk available for btrfs in just a > single host, there should be 6 cosd process in the host when the > disks are all working?
Yes, that is the way common way. > > A single cosd process can not manage several disks? > Yes and no. A single cosd process simply wants a mount point. If you look closer, the init script simply mounts the device specified by 'btrfs devs' in the configuration. You could run LVM, mdadm or even a btrfs multi-disk volume under a mountpoint, this way you could have on cosd process per disk. I would recommend running one cosd process per disk, it takes a bit more memory (about 800M per cosd), but this way Ceph can take the full advantage of all the available diskspace. If you have multiple hosts I would recommend making a CRUSH map which makes sure your data replicas are not stored within the same physical machine: http://ceph.newdream.net/wiki/Custom_data_placement_with_CRUSH The newer versions of Ceph will make a basic CRUSH map based on the ceph.conf, as far as I know it will prevent saving replicas on the same node. However, I would recommended checking your CRUSH map to make sure it does. > How should the ceph.conf be configured for this scenario? For example: [osd.0] host = node01 btrfs devs = /dev/sda [osd.1] host = node01 btrfs devs = /dev/sdb [osd.2] host = node01 btrfs devs = /dev/sdc etc, etc The init script and mkcephfs will then format the specified drives with btrfs and mount it when the OSD starts. I would also recommend running your journal on a separate drive: http://ceph.newdream.net/wiki/Troubleshooting#Performance Wido > > > Thx! > -- > 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 -- 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
