ceph-volume
ceph-volume
is a Ceph tool used to manage and provision OSDs (Object Storage Daemons) on a Ceph cluster. It supports various types of storage backends (e.g., lvm
, raw
, bluestore
, filestore
) and provides functionality for creating, listing, and destroying OSDs.
Here are the relevant subcommands and their common usage:
Common ceph-volume
Subcommands
ceph-volume
Subcommands1. ceph-volume lvm
The ceph-volume lvm
subcommand is used to manage OSDs backed by LVM (Logical Volume Manager). Ceph OSDs are often deployed using bluestore
or filestore
on LVM partitions.
ceph-volume lvm create
ceph-volume lvm create
Creates a new OSD backed by LVM.
Example:
This command creates a new OSD on the device /dev/sdb
. By default, it creates a bluestore
OSD, but you can specify filestore
if needed:
Example for
filestore
:
ceph-volume lvm list
ceph-volume lvm list
Lists all OSDs that are backed by LVM.
Example:
This displays detailed information about all LVM-backed OSDs in the system.
ceph-volume lvm zap
ceph-volume lvm zap
Destroys the contents of a device (zaps) to prepare it for reuse.
Example:
This wipes all data and partitioning information from the device /dev/sdb
, making it ready for new OSD creation.
ceph-volume lvm activate
ceph-volume lvm activate
Activates an existing OSD by associating it with the Ceph cluster.
Example:
This activates all LVM-backed OSDs in the system, making them part of the running Ceph cluster.
2. ceph-volume raw
The ceph-volume raw
subcommand is used to manage OSDs without LVM, particularly for bluestore
OSDs that don't require LVM as a backend.
ceph-volume raw create
ceph-volume raw create
Creates a new OSD without LVM.
Example:
This creates a bluestore
OSD on the raw device /dev/sdc
without using LVM.
ceph-volume raw list
ceph-volume raw list
Lists all OSDs that are not backed by LVM (raw OSDs).
Example:
This displays detailed information about all raw OSDs in the system.
ceph-volume raw zap
ceph-volume raw zap
Zaps (wipes) a raw device to prepare it for reuse.
Example:
This wipes all data and partitioning information from the raw device /dev/sdc
, preparing it for reuse.
3. ceph-volume simple
The ceph-volume simple
subcommand is a legacy command used to manage OSDs before lvm
and raw
methods were introduced. It's now deprecated but still supported for backward compatibility.
ceph-volume simple scan
ceph-volume simple scan
Scans a device to gather information about existing OSDs.
Example:
This scans the device /dev/sdd
to check if an OSD is already present or if it can be reused.
ceph-volume simple activate
ceph-volume simple activate
Activates an existing OSD using the legacy simple
method.
Example:
This activates all OSDs managed by the simple
backend.
4. ceph-volume inventory
The ceph-volume inventory
subcommand is used to display the inventory of available devices that can be used for OSD creation.
ceph-volume inventory
ceph-volume inventory
Lists all available devices on the host that can be used for OSD creation, showing if they are zapped, have partitions, or contain OSDs.
Example:
This command provides detailed information about all devices available for OSD use on the system, indicating their status.
5. ceph-volume trigger
The ceph-volume trigger
subcommand allows manual triggering of specific events for OSDs, such as triggering a rescan of LVM devices.
ceph-volume trigger rescan
ceph-volume trigger rescan
Triggers a rescan of LVM devices to ensure that all OSDs are properly detected and activated.
Example:
This forces a rescan of LVM devices, ensuring that the cluster has up-to-date information on all OSDs.
6. ceph-volume systemd
The ceph-volume systemd
subcommand helps manage the interaction between OSDs and systemd units for service management.
ceph-volume systemd list
ceph-volume systemd list
Lists all the systemd unit files related to OSDs.
Example:
This command displays all the systemd units managing OSDs, showing their statuses.
ceph-volume systemd activate
ceph-volume systemd activate
Activates systemd unit files for OSDs.
Example:
This activates all the systemd unit files responsible for managing the OSDs.
Conclusion
The ceph-volume
tool is essential for managing the lifecycle of Ceph OSDs, offering flexibility in choosing between LVM and raw devices. Its subcommands allow you to create, list, activate, and zap OSDs, and manage the inventory of available devices. By providing options for both legacy and modern methods of OSD provisioning, ceph-volume
ensures the robust and efficient management of Ceph storage resources.
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