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ceph/doc/man/8/rbd.rst
yonghengdexin735 ad25da3a62 doc/rbd:add info for rbd group 
Signed-off-by: yonghengdexin735 <zhang.zezhu@zte.com.cn>
2017-09-11 17:56:25 +08:00

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:orphan:
===============================================
rbd -- manage rados block device (RBD) images
===============================================
.. program:: rbd
Synopsis
========
| **rbd** [ -c *ceph.conf* ] [ -m *monaddr* ] [--cluster *cluster-name*]
[ -p | --pool *pool* ] [ *command* ... ]
Description
===========
**rbd** is a utility for manipulating rados block device (RBD) images,
used by the Linux rbd driver and the rbd storage driver for QEMU/KVM.
RBD images are simple block devices that are striped over objects and
stored in a RADOS object store. The size of the objects the image is
striped over must be a power of two.
Options
=======
.. option:: -c ceph.conf, --conf ceph.conf
Use ceph.conf configuration file instead of the default /etc/ceph/ceph.conf to
determine monitor addresses during startup.
.. option:: -m monaddress[:port]
Connect to specified monitor (instead of looking through ceph.conf).
.. option:: --cluster cluster-name
Use different cluster name as compared to default cluster name *ceph*.
.. option:: -p pool-name, --pool pool-name
Interact with the given pool. Required by most commands.
.. option:: --no-progress
Do not output progress information (goes to standard error by
default for some commands).
Parameters
==========
.. option:: --image-format format-id
Specifies which object layout to use. The default is 2.
* format 1 - (deprecated) Use the original format for a new rbd image. This
format is understood by all versions of librbd and the kernel rbd module,
but does not support newer features like cloning.
* format 2 - Use the second rbd format, which is supported by
librbd and kernel since version 3.11 (except for striping). This adds
support for cloning and is more easily extensible to allow more
features in the future.
.. option:: -s size-in-M/G/T, --size size-in-M/G/T
Specifies the size of the new rbd image or the new size of the existing rbd
image in M/G/T. If no suffix is given, unit M is assumed.
.. option:: --object-size size-in-B/K/M
Specifies the object size in B/K/M. Object size will be rounded up the
nearest power of two; if no suffix is given, unit B is assumed. The default
object size is 4M, smallest is 4K and maximum is 32M.
.. option:: --stripe-unit size-in-B/K/M
Specifies the stripe unit size in B/K/M. If no suffix is given, unit B is
assumed. See striping section (below) for more details.
.. option:: --stripe-count num
Specifies the number of objects to stripe over before looping back
to the first object. See striping section (below) for more details.
.. option:: --snap snap
Specifies the snapshot name for the specific operation.
.. option:: --id username
Specifies the username (without the ``client.`` prefix) to use with the map command.
.. option:: --keyring filename
Specifies a keyring file containing a secret for the specified user
to use with the map command. If not specified, the default keyring
locations will be searched.
.. option:: --keyfile filename
Specifies a file containing the secret key of ``--id user`` to use with the map command.
This option is overridden by ``--keyring`` if the latter is also specified.
.. option:: --shared lock-tag
Option for `lock add` that allows multiple clients to lock the
same image if they use the same tag. The tag is an arbitrary
string. This is useful for situations where an image must
be open from more than one client at once, like during
live migration of a virtual machine, or for use underneath
a clustered filesystem.
.. option:: --format format
Specifies output formatting (default: plain, json, xml)
.. option:: --pretty-format
Make json or xml formatted output more human-readable.
.. option:: -o krbd-options, --options krbd-options
Specifies which options to use when mapping or unmapping an image via the
rbd kernel driver. krbd-options is a comma-separated list of options
(similar to mount(8) mount options). See kernel rbd (krbd) options section
below for more details.
.. option:: --read-only
Map the image read-only. Equivalent to -o ro.
.. option:: --image-feature feature-name
Specifies which RBD format 2 feature should be enabled when creating
an image. Multiple features can be enabled by repeating this option
multiple times. The following features are supported:
* layering: layering support
* striping: striping v2 support
* exclusive-lock: exclusive locking support
* object-map: object map support (requires exclusive-lock)
* fast-diff: fast diff calculations (requires object-map)
* deep-flatten: snapshot flatten support
* journaling: journaled IO support (requires exclusive-lock)
.. option:: --image-shared
Specifies that the image will be used concurrently by multiple clients.
This will disable features that are dependent upon exclusive ownership
of the image.
.. option:: --whole-object
Specifies that the diff should be limited to the extents of a full object
instead of showing intra-object deltas. When the object map feature is
enabled on an image, limiting the diff to the object extents will
dramatically improve performance since the differences can be computed
by examining the in-memory object map instead of querying RADOS for each
object within the image.
.. option:: --limit
Specifies the limit for the number of snapshots permitted.
Commands
========
.. TODO rst "option" directive seems to require --foo style options, parsing breaks on subcommands.. the args show up as bold too
:command:`ls` [-l | --long] [*pool-name*]
Will list all rbd images listed in the rbd_directory object. With
-l, also show snapshots, and use longer-format output including
size, parent (if clone), format, etc.
:command:`du` [-p | --pool *pool-name*] [*image-spec* | *snap-spec*]
Will calculate the provisioned and actual disk usage of all images and
associated snapshots within the specified pool. It can also be used against
individual images and snapshots.
If the RBD fast-diff feature is not enabled on images, this operation will
require querying the OSDs for every potential object within the image.
:command:`info` *image-spec* | *snap-spec*
Will dump information (such as size and object size) about a specific rbd image.
If image is a clone, information about its parent is also displayed.
If a snapshot is specified, whether it is protected is shown as well.
:command:`create` (-s | --size *size-in-M/G/T*) [--image-format *format-id*] [--object-size *size-in-B/K/M*] [--stripe-unit *size-in-B/K/M* --stripe-count *num*] [--image-feature *feature-name*]... [--image-shared] *image-spec*
Will create a new rbd image. You must also specify the size via --size. The
--stripe-unit and --stripe-count arguments are optional, but must be used together.
:command:`clone` [--object-size *size-in-B/K/M*] [--stripe-unit *size-in-B/K/M* --stripe-count *num*] [--image-feature *feature-name*] [--image-shared] *parent-snap-spec* *child-image-spec*
Will create a clone (copy-on-write child) of the parent snapshot.
Object size will be identical to that of the parent image unless
specified. Size will be the same as the parent snapshot. The --stripe-unit
and --stripe-count arguments are optional, but must be used together.
The parent snapshot must be protected (see `rbd snap protect`).
This requires image format 2.
:command:`flatten` *image-spec*
If image is a clone, copy all shared blocks from the parent snapshot and
make the child independent of the parent, severing the link between
parent snap and child. The parent snapshot can be unprotected and
deleted if it has no further dependent clones.
This requires image format 2.
:command:`children` *snap-spec*
List the clones of the image at the given snapshot. This checks
every pool, and outputs the resulting poolname/imagename.
This requires image format 2.
:command:`resize` (-s | --size *size-in-M/G/T*) [--allow-shrink] *image-spec*
Resize rbd image. The size parameter also needs to be specified.
The --allow-shrink option lets the size be reduced.
:command:`rm` *image-spec*
Delete an rbd image (including all data blocks). If the image has
snapshots, this fails and nothing is deleted.
:command:`export` [--export-format *format (1 or 2)*] (*image-spec* | *snap-spec*) [*dest-path*]
Export image to dest path (use - for stdout).
The --export-format accepts '1' or '2' currently. Format 2 allow us to export not only the content
of image, but also the snapshots and other properties, such as image_order, features.
:command:`import` [--export-format *format (1 or 2)*] [--image-format *format-id*] [--object-size *size-in-B/K/M*] [--stripe-unit *size-in-B/K/M* --stripe-count *num*] [--image-feature *feature-name*]... [--image-shared] *src-path* [*image-spec*]
Create a new image and imports its data from path (use - for
stdin). The import operation will try to create sparse rbd images
if possible. For import from stdin, the sparsification unit is
the data block size of the destination image (object size).
The --stripe-unit and --stripe-count arguments are optional, but must be
used together.
The --export-format accepts '1' or '2' currently. Format 2 allow us to import not only the content
of image, but also the snapshots and other properties, such as image_order, features.
:command:`export-diff` [--from-snap *snap-name*] [--whole-object] (*image-spec* | *snap-spec*) *dest-path*
Export an incremental diff for an image to dest path (use - for stdout). If
an initial snapshot is specified, only changes since that snapshot are included; otherwise,
any regions of the image that contain data are included. The end snapshot is specified
using the standard --snap option or @snap syntax (see below). The image diff format includes
metadata about image size changes, and the start and end snapshots. It efficiently represents
discarded or 'zero' regions of the image.
:command:`merge-diff` *first-diff-path* *second-diff-path* *merged-diff-path*
Merge two continuous incremental diffs of an image into one single diff. The
first diff's end snapshot must be equal with the second diff's start snapshot.
The first diff could be - for stdin, and merged diff could be - for stdout, which
enables multiple diff files to be merged using something like
'rbd merge-diff first second - | rbd merge-diff - third result'. Note this command
currently only support the source incremental diff with stripe_count == 1
:command:`import-diff` *src-path* *image-spec*
Import an incremental diff of an image and applies it to the current image. If the diff
was generated relative to a start snapshot, we verify that snapshot already exists before
continuing. If there was an end snapshot we verify it does not already exist before
applying the changes, and create the snapshot when we are done.
:command:`diff` [--from-snap *snap-name*] [--whole-object] *image-spec* | *snap-spec*
Dump a list of byte extents in the image that have changed since the specified start
snapshot, or since the image was created. Each output line includes the starting offset
(in bytes), the length of the region (in bytes), and either 'zero' or 'data' to indicate
whether the region is known to be zeros or may contain other data.
:command:`cp` (*src-image-spec* | *src-snap-spec*) *dest-image-spec*
Copy the content of a src-image into the newly created dest-image.
dest-image will have the same size, object size, and image format as src-image.
:command:`mv` *src-image-spec* *dest-image-spec*
Rename an image. Note: rename across pools is not supported.
:command:`image-meta list` *image-spec*
Show metadata held on the image. The first column is the key
and the second column is the value.
:command:`image-meta get` *image-spec* *key*
Get metadata value with the key.
:command:`image-meta set` *image-spec* *key* *value*
Set metadata key with the value. They will displayed in `image-meta list`.
:command:`image-meta remove` *image-spec* *key*
Remove metadata key with the value.
:command:`object-map rebuild` *image-spec* | *snap-spec*
Rebuild an invalid object map for the specified image. An image snapshot can be
specified to rebuild an invalid object map for a snapshot.
:command:`snap ls` *image-spec*
Dump the list of snapshots inside a specific image.
:command:`snap create` *snap-spec*
Create a new snapshot. Requires the snapshot name parameter specified.
:command:`snap rollback` *snap-spec*
Rollback image content to snapshot. This will iterate through the entire blocks
array and update the data head content to the snapshotted version.
:command:`snap rm` [--force] *snap-spec*
Remove the specified snapshot.
:command:`snap purge` *image-spec*
Remove all snapshots from an image.
:command:`snap protect` *snap-spec*
Protect a snapshot from deletion, so that clones can be made of it
(see `rbd clone`). Snapshots must be protected before clones are made;
protection implies that there exist dependent cloned children that
refer to this snapshot. `rbd clone` will fail on a nonprotected
snapshot.
This requires image format 2.
:command:`snap unprotect` *snap-spec*
Unprotect a snapshot from deletion (undo `snap protect`). If cloned
children remain, `snap unprotect` fails. (Note that clones may exist
in different pools than the parent snapshot.)
This requires image format 2.
:command:`snap limit set` [--limit] *limit* *image-spec*
Set a limit for the number of snapshots allowed on an image.
:command:`snap limit clear` *image-spec*
Remove any previously set limit on the number of snapshots allowed on
an image.
:command:`map` [-o | --options *krbd-options* ] [--read-only] *image-spec* | *snap-spec*
Map the specified image to a block device via the rbd kernel module.
:command:`unmap` [-o | --options *krbd-options* ] *image-spec* | *snap-spec* | *device-path*
Unmap the block device that was mapped via the rbd kernel module.
:command:`showmapped`
Show the rbd images that are mapped via the rbd kernel module.
:command:`nbd map` [--device *device-path*] [--read-only] *image-spec* | *snap-spec*
Map the specified image to a block device via the rbd-nbd tool.
:command:`nbd unmap` *device-path*
Unmap the block device that was mapped via the rbd-nbd tool.
:command:`nbd list`
Show the list of used nbd devices via the rbd-nbd tool.
:command:`status` *image-spec*
Show the status of the image, including which clients have it open.
:command:`feature disable` *image-spec* *feature-name*...
Disable the specified feature on the specified image. Multiple features can
be specified.
:command:`feature enable` *image-spec* *feature-name*...
Enable the specified feature on the specified image. Multiple features can
be specified.
:command:`lock list` *image-spec*
Show locks held on the image. The first column is the locker
to use with the `lock remove` command.
:command:`lock add` [--shared *lock-tag*] *image-spec* *lock-id*
Lock an image. The lock-id is an arbitrary name for the user's
convenience. By default, this is an exclusive lock, meaning it
will fail if the image is already locked. The --shared option
changes this behavior. Note that locking does not affect
any operation other than adding a lock. It does not
protect an image from being deleted.
:command:`lock remove` *image-spec* *lock-id* *locker*
Release a lock on an image. The lock id and locker are
as output by lock ls.
:command:`bench` --io-type <read | write> [--io-size *size-in-B/K/M/G/T*] [--io-threads *num-ios-in-flight*] [--io-total *size-in-B/K/M/G/T*] [--io-pattern seq | rand] *image-spec*
Generate a series of IOs to the image and measure the IO throughput and
latency. If no suffix is given, unit B is assumed for both --io-size and
--io-total. Defaults are: --io-size 4096, --io-threads 16, --io-total 1G,
--io-pattern seq.
:command:`trash ls` [*pool-name*]
List all entries from trash.
:command:`trash mv` *image-spec*
Move an image to the trash. Images, even ones actively in-use by
clones, can be moved to the trash and deleted at a later time.
:command:`trash rm` *image-id*
Delete an image from trash. If image deferment time has not expired
you can not removed it unless use force. But an actively in-use by clones
or has snapshots can not be removed.
:command:`trash restore` *image-id*
Restore an image from trash.
:command:`group create` *group-spec*
Create a consistency group.
:command:`group list` [-p | --pool *pool-name*]
List rbd consistency groups.
:command:`group remove` *group-spec*
Delete a consistency group.
:command:`group image add` *group-spec* *image-spec*
Add an image to a consistency group.
:command:`group image list` *group-spec*
List images in a consistency group.
:command:`group image remove` *group-spec* *image-spec*
Remove an image from a consistency group.
Image, snap and group specs
===========================
| *image-spec* is [*pool-name*]/*image-name*
| *snap-spec* is [*pool-name*]/*image-name*\ @\ *snap-name*
| *group-spec* is [*pool-name*]/*group-name*
The default for *pool-name* is "rbd". If an image name contains a slash
character ('/'), *pool-name* is required.
You may specify each name individually, using --pool, --image and --snap
options, but this is discouraged in favor of the above spec syntax.
Striping
========
RBD images are striped over many objects, which are then stored by the
Ceph distributed object store (RADOS). As a result, read and write
requests for the image are distributed across many nodes in the
cluster, generally preventing any single node from becoming a
bottleneck when individual images get large or busy.
The striping is controlled by three parameters:
.. option:: object-size
The size of objects we stripe over is a power of two. It will be rounded up the nearest power of two.
The default object size is 4 MB, smallest is 4K and maximum is 32M.
.. option:: stripe_unit
Each [*stripe_unit*] contiguous bytes are stored adjacently in the same object, before we move on
to the next object.
.. option:: stripe_count
After we write [*stripe_unit*] bytes to [*stripe_count*] objects, we loop back to the initial object
and write another stripe, until the object reaches its maximum size. At that point,
we move on to the next [*stripe_count*] objects.
By default, [*stripe_unit*] is the same as the object size and [*stripe_count*] is 1. Specifying a different
[*stripe_unit*] requires that the STRIPINGV2 feature be supported (added in Ceph v0.53) and format 2 images be
used.
Kernel rbd (krbd) options
=========================
Most of these options are useful mainly for debugging and benchmarking. The
default values are set in the kernel and may therefore depend on the version of
the running kernel.
Per client instance `rbd map` options:
* fsid=aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee - FSID that should be assumed by
the client.
* ip=a.b.c.d[:p] - IP and, optionally, port the client should use.
* share - Enable sharing of client instances with other mappings (default).
* noshare - Disable sharing of client instances with other mappings.
* crc - Enable CRC32C checksumming for data writes (default).
* nocrc - Disable CRC32C checksumming for data writes.
* cephx_require_signatures - Require cephx message signing (since 3.19,
default).
* nocephx_require_signatures - Don't require cephx message signing (since
3.19).
* tcp_nodelay - Disable Nagle's algorithm on client sockets (since 4.0,
default).
* notcp_nodelay - Enable Nagle's algorithm on client sockets (since 4.0).
* cephx_sign_messages - Enable message signing (since 4.4, default).
* nocephx_sign_messages - Disable message signing (since 4.4).
* mount_timeout=x - A timeout on various steps in `rbd map` and `rbd unmap`
sequences (default is 60 seconds). In particular, since 4.2 this can be used
to ensure that `rbd unmap` eventually times out when there is no network
connection to a cluster.
* osdkeepalive=x - OSD keepalive timeout (default is 5 seconds).
* osd_idle_ttl=x - OSD idle TTL (default is 60 seconds).
Per mapping (block device) `rbd map` options:
* rw - Map the image read-write (default).
* ro - Map the image read-only. Equivalent to --read-only.
* queue_depth=x - queue depth (since 4.2, default is 128 requests).
* lock_on_read - Acquire exclusive lock on reads, in addition to writes and
discards (since 4.9).
* exclusive - Disable automatic exclusive lock transitions (since 4.12).
`rbd unmap` options:
* force - Force the unmapping of a block device that is open (since 4.9). The
driver will wait for running requests to complete and then unmap; requests
sent to the driver after initiating the unmap will be failed.
Examples
========
To create a new rbd image that is 100 GB::
rbd create mypool/myimage --size 102400
To use a non-default object size (8 MB)::
rbd create mypool/myimage --size 102400 --object-size 8M
To delete an rbd image (be careful!)::
rbd rm mypool/myimage
To create a new snapshot::
rbd snap create mypool/myimage@mysnap
To create a copy-on-write clone of a protected snapshot::
rbd clone mypool/myimage@mysnap otherpool/cloneimage
To see which clones of a snapshot exist::
rbd children mypool/myimage@mysnap
To delete a snapshot::
rbd snap rm mypool/myimage@mysnap
To map an image via the kernel with cephx enabled::
rbd map mypool/myimage --id admin --keyfile secretfile
To map an image via the kernel with different cluster name other than default *ceph*::
rbd map mypool/myimage --cluster cluster-name
To unmap an image::
rbd unmap /dev/rbd0
To create an image and a clone from it::
rbd import --image-format 2 image mypool/parent
rbd snap create mypool/parent@snap
rbd snap protect mypool/parent@snap
rbd clone mypool/parent@snap otherpool/child
To create an image with a smaller stripe_unit (to better distribute small writes in some workloads)::
rbd create mypool/myimage --size 102400 --stripe-unit 65536B --stripe-count 16
To change an image from one image format to another, export it and then
import it as the desired image format::
rbd export mypool/myimage@snap /tmp/img
rbd import --image-format 2 /tmp/img mypool/myimage2
To lock an image for exclusive use::
rbd lock add mypool/myimage mylockid
To release a lock::
rbd lock remove mypool/myimage mylockid client.2485
To list images from trash::
rbd trash ls mypool
To defer delete an image (use *--delay* to set delay-time, default is 0)::
rbd trash mv mypool/myimage
To delete an image from trash (be careful!)::
rbd trash rm mypool/myimage-id
To force delete an image from trash (be careful!)::
rbd trash rm mypool/myimage-id --force
To restore an image from trash::
rbd trash restore mypool/myimage-id
To restore an image from trash and rename it::
rbd trash restore mypool/myimage-id --image mynewimage
Availability
============
**rbd** is part of Ceph, a massively scalable, open-source, distributed storage system. Please refer to
the Ceph documentation at http://ceph.com/docs for more information.
See also
========
:doc:`ceph <ceph>`\(8),
:doc:`rados <rados>`\(8)
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