Manipulating object content

With the ceph-objectstore-tool utility, you can get or set bytes on an object.

Before you begin

Before you begin, make sure that you have the following prerequisites in place:
  • Root-level access to the Ceph OSD node.
  • Stopping the ceph-osd daemon.

Procedure

  1. Verify that the appropriate OSD is down.
    systemctl status ceph-osd@OSD_ID
    For example,
    [root@host01 ~]# systemctl status ceph-osd@1
  2. Find the object by listing the objects of the OSD or placement group (PG).
  3. Log in to the OSD container.
    cephadm shell --name osd.OSD_ID
    For example,
    [root@host01 ~]# cephadm shell --name osd.0
  4. Create a backup and working copy of the object.
    This must be done before setting bytes on an object.
    ceph-objectstore-tool --data-path PATH_TO_OSD --pgid PG_ID \
OBJECT \
get-bytes > OBJECT_FILE_NAME
    For example,
    [ceph: root@host01 /]# ceph-objectstore-tool --data-path /var/lib/ceph/osd/ceph-0 --pgid 0.1c \
'{"oid":"zone_info.default","key":"","snapid":-2,"hash":235010478,"max":0,"pool":11,"namespace":""}'  \
get-bytes > zone_info.default.backup

[ceph: root@host01 /]#  ceph-objectstore-tool --data-path /var/lib/ceph/osd/ceph-0 --pgid 0.1c \
'{"oid":"zone_info.default","key":"","snapid":-2,"hash":235010478,"max":0,"pool":11,"namespace":""}'  \
get-bytes > zone_info.default.working-copy
  5. Edit the working copy object file and modify the object contents.
  6. Set the bytes of the object.
    ceph-objectstore-tool --data-path PATH_TO_OSD --pgid PG_ID \
OBJECT \
set-bytes < OBJECT_FILE_NAME
    For example,
    [ceph: root@host01 /]# ceph-objectstore-tool --data-path /var/lib/ceph/osd/ceph-0 --pgid 0.1c \
'{"oid":"zone_info.default","key":"","snapid":-2,"hash":235010478,"max":0,"pool":11,"namespace":""}' \
set-bytes < zone_info.default.working-copy