Note: it is similar to Creating a Ceph OSD from a designated disk partition but simpler.
In a nutshell, to use the remaining space from /dev/sda and assuming Ceph is already configured in /etc/ceph/ceph.conf it is enough to:
$ sgdisk --largest-new=$PARTITION --change-name="$PARTITION:ceph data" \ --partition-guid=$PARTITION:$OSD_UUID \ --typecode=$PARTITION:$PTYPE_UUID -- /dev/sda $ partprobe $ ceph-disk prepare /dev/sda$PARTITION $ ceph-disk activate /dev/sda$PARTITION
The /etc/ceph/ceph.conf is assumed to contain the IP of the monitors and instructions to automatically set the location of a new OSD:
osd_crush_update_on_start = 1 osd_crush_location = datacenter=ovh
Let say the /dev/sda disk has spare space and is configured with GPT:
$ sgdisk --print /dev/sda Disk /dev/sda: 3907029168 sectors, 1.8 TiB Logical sector size: 512 bytes Disk identifier (GUID): E409D145-0A08-4768-A6A0-9E5C68265944 Partition table holds up to 128 entries First usable sector is 34, last usable sector is 3907029134 Partitions will be aligned on 2048-sector boundaries Total free space is 2801113197 sectors (1.3 TiB) Number Start (sector) End (sector) Size Code Name 1 4096 40962047 19.5 GiB FD00 Linux RAID 2 40962048 57343999 7.8 GiB 8200 Linux swap 3 57344000 1105919999 500.0 GiB 8E00 Linux LVM
A random UUID is computed and set to an environment variable to uniquely identify the new OSD:
OSD_UUID=$(uuidgen -r)
The typecode designating a Ceph data disk is set to another environment variable:
PTYPE_UUID=4fbd7e29-9d25-41b8-afd0-062c0ceff05d
A partition number is chosen to be the next one available and also set to an environment variable:
PARTITION=4
The new partition is created with:
$ sgdisk --largest-new=$PARTITION --change-name="$PARTITION:ceph data" \ --partition-guid=$PARTITION:$OSD_UUID \ --typecode=$PARTITION:$PTYPE_UUID -- /dev/sda Warning: The kernel is still using the old partition table. The new table will be used at the next reboot. The operation has completed successfully. $ sgdisk --print /dev/sda Disk /dev/sda: 3907029168 sectors, 1.8 TiB Logical sector size: 512 bytes Disk identifier (GUID): E409D145-0A08-4768-A6A0-9E5C68265944 Partition table holds up to 128 entries First usable sector is 34, last usable sector is 3907029134 Partitions will be aligned on 2048-sector boundaries Total free space is 4062 sectors (2.0 MiB) Number Start (sector) End (sector) Size Code Name 1 4096 40962047 19.5 GiB FD00 Linux RAID 2 40962048 57343999 7.8 GiB 8200 Linux swap 3 57344000 1105919999 500.0 GiB 8E00 Linux LVM 4 1105920000 3907029134 1.3 TiB FFFF ceph data
But it will not show up until partprobe is run:
$ ls -l /dev/sda4 ls: cannot access /dev/sda4: No such file or directory $ partprobe $ ls -l /dev/sda4 brw-rw---- 1 root disk 8, 4 May 8 17:34 /dev/sda4
The partition is prepared (i.e. formatted) as an OSD and the journal will be included in it by default:
$ ceph-disk prepare /dev/sda4
meta-data=/dev/sda4 isize=2048 agcount=32, agsize=10941833 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=350138641, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=170966, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
It is then activated, meaning the file system is mounted and the OSD daemon running:
$ ceph-disk activate /dev/sda4 got latest monmap 2014-05-08 17:34:46.390267 7fa966361780 -1 journal FileJournal::_open: disabling aio for non-block journal. Use journal_force_aio to force use of aio anyway 2014-05-08 17:34:46.611058 7fa966361780 -1 journal FileJournal::_open: disabling aio for non-block journal. Use journal_force_aio to force use of aio anyway 2014-05-08 17:34:46.661352 7fa966361780 -1 filestore(/var/lib/ceph/tmp/mnt.foozff) could not find 23c2fcde/osd_superblock/0//-1 in index: (2) No such file or directory 2014-05-08 17:34:46.902508 7fa966361780 -1 created object store /var/lib/ceph/tmp/mnt.foozff journal /var/lib/ceph/tmp/mnt.foozff/journal for osd.6 fsid 571bb920-6d85-44d7-9ec\ a-1bc114d1cd75 2014-05-08 17:34:46.909010 7fa966361780 -1 auth: error reading file: /var/lib/ceph/tmp/mnt.foozff/keyring: can't open /var/lib/ceph/tmp/mnt.foozff/keyring: (2) No such file or\ directory 2014-05-08 17:34:46.971750 7fa966361780 -1 created new key in keyring /var/lib/ceph/tmp/mnt.foozff/keyring added key for osd.6 $ df -h Filesystem Size Used Avail Use% Mounted on rootfs 20G 3.2G 15G 18% / /dev/root 20G 3.2G 15G 18% / devtmpfs 7.8G 4.0K 7.8G 1% /dev none 1.6G 284K 1.6G 1% /run none 5.0M 0 5.0M 0% /run/lock none 7.8G 0 7.8G 0% /run/shm cgroup 7.8G 0 7.8G 0% /sys/fs/cgroup /dev/sdb4 1.4T 705G 631G 53% /var/lib/ceph/osd/ceph-2 /dev/sda4 1.4T 1.1G 1.4T 1% /var/lib/ceph/osd/ceph-6