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diff --git a/src/ceph/doc/man/8/rbd.rst b/src/ceph/doc/man/8/rbd.rst new file mode 100644 index 0000000..c37ca44 --- /dev/null +++ b/src/ceph/doc/man/8/rbd.rst @@ -0,0 +1,615 @@ +: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. + +Image and snap specs +==================== + +| *image-spec* is [*pool-name*]/*image-name* +| *snap-spec* is [*pool-name*]/*image-name*\ @\ *snap-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) |