Creating a Ceph OSD from a designated disk partition


When a new Ceph OSD is setup with ceph-disk on a designated disk partition ( say /dev/sdc3 ), it will not be prepared and the sgdisk command must be run manually:

# osd_uuid=$(uuidgen)



sgdisk --change-name="${partition_number}:ceph data" \

   --partition-guid="${partition\_number}:{osd\_uuid}" \\

sgdisk --info=3 /dev/sdc

Partition GUID code: 89C57F98-2FE5-4DC0-89C1-F3AD0CEFF2BE (Unknown) Partition unique GUID: 22FD939D-C203-43A9-966A-04570B63FABB ... Partition name: 'ceph data'

The ptype_tobe is a partition type known to Ceph and set when it is being worked on. Assuming /dev/sda is a SSD disk from which a journal partition can be created, the OSD can be prepared with:

# ceph-disk prepare --osd-uuid "$osd_uuid" \ --fs-type xfs --cluster ceph -- \ /dev/sdc3 /dev/sda WARNING:ceph-disk:OSD will not be hot-swappable if ... Information: Moved requested sector from 34 to 2048 in order to align on 2048-sector boundaries. The operation has completed successfully. meta-data=/dev/sdc3 isize=2048 agcount=4, agsize=61083136 blks = sectsz=512 attr=2, projid32bit=0 data = bsize=4096 blocks=244332544, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 log =internal log bsize=4096 blocks=119303, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0

The journal and data partitions should be associated with each other :

# ceph-disk list /dev/sda : /dev/sda1 ceph journal, for /dev/sdc3 /dev/sdb : /dev/sdb2 other, ext4, mounted on / /dev/sdb3 swap, swap /dev/sdc : /dev/sdc1 other, primary /dev/sdc2 other, ext4, mounted on /mnt /dev/sdc3 ceph data, prepared, cluster ceph, journal /dev/sda1

The type of the partition can be changed so that udev triggered scripts notice it and provision the osd.

# ptype=4fbd7e29-9d25-41b8-afd0-062c0ceff05d

sgdisk --typecode="${partition_number}:${ptype}" /dev/sdc

udevadm trigger --subsystem-match=block --action=add

df | grep /var/lib/ceph

/dev/sdc3 932G 160M 931G 1% /var/lib/ceph/osd/ceph-9