Ceph Block Device块设备的使用

(1) 使用要求：
    a) 集群环境搭建成功
    b) 集群的状态是 active+clean。
    c) 节点配置，将admnode也做为client-node使用
          主机名         角色               磁盘                         
        ================================================================
        a) admnode      deploy-node,client-node     
        b) node1          mon1,osd.2,mds        Disk(/dev/sdb  capacity:10G)
        c) node2          osd.0,mon2            Disk(/dev/sdb  capacity:10G)
        d) node3          osd.1,mon3            Disk(/dev/sdb  capacity:10G)   

(2) 使用方法 http://docs.ceph.com/docs/master/start/quick-rbd/
    a) 在client-node建立Block Device Image，这里使用默认的rbd pool(使用ceph osd lspools查看)
        # ceph osd lspools
        0 rbd,
       
        # rbd create --size 1024 blockDevImg
        # rbd ls rbd
        blockDevImg
       
        # rbd info blockDevImg
            rbd image 'blockDevImg':
                size 1024 MB in 256 objects
                order 22 (4096 kB objects)
                block_name_prefix: rb.0.1041.74b0dc51
                format: 1
               
    b) 在client-node将该image 映射给一个 block device。
        # sudo rbd map blockDevImg --name client.admin       
        /dev/rbd0
       
    c) 使用该block device在client-node上建立一个文件系统。
        # sudo mkfs.ext4 -m0 /dev/rbd/rbd/blockDevImg
        mke2fs 1.42.9 (28-Dec-2013)
        Discarding device blocks: done                           
        Filesystem label=
        OS type: Linux
        Block size=4096 (log=2)
        Fragment size=4096 (log=2)
        Stride=1024 blocks, Stripe width=1024 blocks
        65536 inodes, 262144 blocks
        0 blocks (0.00%) reserved for the super user
        First data block=0
        Maximum filesystem blocks=268435456
        8 block groups
        32768 blocks per group, 32768 fragments per group
        8192 inodes per group
        Superblock backups stored on blocks:
            32768, 98304, 163840, 229376

        Allocating group tables: done                           
        Writing inode tables: done                           
        Creating journal (8192 blocks): done
        Writing superblocks and filesystem accounting information: done

        d) 挂载文件系统
        # sudo mkdir /mnt/ceph-block-device
        # sudo mount /dev/rbd/rbd/blockDevImg /mnt/ceph-block-device
        # cd /mnt/ceph-block-device
        # mount
        ...
        /dev/rbd0 on /mnt/ceph-block-device type ext4 (rw,relatime,seclabel,stripe=1024,data=ordered)