mirror of
https://github.com/ceph/ceph
synced 2024-12-27 14:03:25 +00:00
716 lines
17 KiB
ReStructuredText
716 lines
17 KiB
ReStructuredText
=======
|
|
Pools
|
|
=======
|
|
|
|
When you first deploy a cluster without creating a pool, Ceph uses the default
|
|
pools for storing data. A pool provides you with:
|
|
|
|
- **Resilience**: You can set how many OSD are allowed to fail without losing data.
|
|
For replicated pools, it is the desired number of copies/replicas of an object.
|
|
A typical configuration stores an object and one additional copy
|
|
(i.e., ``size = 2``), but you can determine the number of copies/replicas.
|
|
For `erasure coded pools <../erasure-code>`_, it is the number of coding chunks
|
|
(i.e. ``m=2`` in the **erasure code profile**)
|
|
|
|
- **Placement Groups**: You can set the number of placement groups for the pool.
|
|
A typical configuration uses approximately 100 placement groups per OSD to
|
|
provide optimal balancing without using up too many computing resources. When
|
|
setting up multiple pools, be careful to ensure you set a reasonable number of
|
|
placement groups for both the pool and the cluster as a whole.
|
|
|
|
- **CRUSH Rules**: When you store data in a pool, a CRUSH ruleset mapped to the
|
|
pool enables CRUSH to identify a rule for the placement of the object
|
|
and its replicas (or chunks for erasure coded pools) in your cluster.
|
|
You can create a custom CRUSH rule for your pool.
|
|
|
|
- **Snapshots**: When you create snapshots with ``ceph osd pool mksnap``,
|
|
you effectively take a snapshot of a particular pool.
|
|
|
|
- **Set Ownership**: You can set a user ID as the owner of a pool.
|
|
|
|
To organize data into pools, you can list, create, and remove pools.
|
|
You can also view the utilization statistics for each pool.
|
|
|
|
List Pools
|
|
==========
|
|
|
|
To list your cluster's pools, execute::
|
|
|
|
ceph osd lspools
|
|
|
|
On a freshly installed cluster, only the ``rbd`` pool exists.
|
|
|
|
|
|
.. _createpool:
|
|
|
|
Create a Pool
|
|
=============
|
|
|
|
Before creating pools, refer to the `Pool, PG and CRUSH Config Reference`_.
|
|
Ideally, you should override the default value for the number of placement
|
|
groups in your Ceph configuration file, as the default is NOT ideal.
|
|
For details on placement group numbers refer to `setting the number of placement groups`_
|
|
|
|
For example::
|
|
|
|
osd pool default pg num = 100
|
|
osd pool default pgp num = 100
|
|
|
|
To create a pool, execute::
|
|
|
|
ceph osd pool create {pool-name} {pg-num} [{pgp-num}] [replicated] \
|
|
[crush-ruleset-name] [expected-num-objects]
|
|
ceph osd pool create {pool-name} {pg-num} {pgp-num} erasure \
|
|
[erasure-code-profile] [crush-ruleset-name] [expected_num_objects]
|
|
|
|
Where:
|
|
|
|
``{pool-name}``
|
|
|
|
:Description: The name of the pool. It must be unique.
|
|
:Type: String
|
|
:Required: Yes.
|
|
|
|
``{pg-num}``
|
|
|
|
:Description: The total number of placement groups for the pool. See `Placement
|
|
Groups`_ for details on calculating a suitable number. The
|
|
default value ``8`` is NOT suitable for most systems.
|
|
|
|
:Type: Integer
|
|
:Required: Yes
|
|
:Default: 8
|
|
|
|
``{pgp-num}``
|
|
|
|
:Description: The total number of placement groups for placement purposes. This
|
|
**should be equal to the total number of placement groups**, except
|
|
for placement group splitting scenarios.
|
|
|
|
:Type: Integer
|
|
:Required: Yes. Picks up default or Ceph configuration value if not specified.
|
|
:Default: 8
|
|
|
|
``{replicated|erasure}``
|
|
|
|
:Description: The pool type which may either be **replicated** to
|
|
recover from lost OSDs by keeping multiple copies of the
|
|
objects or **erasure** to get a kind of
|
|
`generalized RAID5 <../erasure-code>`_ capability.
|
|
The **replicated** pools require more
|
|
raw storage but implement all Ceph operations. The
|
|
**erasure** pools require less raw storage but only
|
|
implement a subset of the available operations.
|
|
|
|
:Type: String
|
|
:Required: No.
|
|
:Default: replicated
|
|
|
|
``[crush-ruleset-name]``
|
|
|
|
:Description: The name of a CRUSH ruleset to use for this pool. The specified
|
|
ruleset must exist.
|
|
|
|
:Type: String
|
|
:Required: No.
|
|
:Default: For **replicated** pools it is the ruleset specified by the ``osd
|
|
pool default crush replicated ruleset`` config variable. This
|
|
ruleset must exist.
|
|
For **erasure** pools it is ``erasure-code`` if the ``default``
|
|
`erasure code profile`_ is used or ``{pool-name}`` otherwise. This
|
|
ruleset will be created implicitly if it doesn't exist already.
|
|
|
|
|
|
``[erasure-code-profile=profile]``
|
|
|
|
.. _erasure code profile: ../erasure-code-profile
|
|
|
|
:Description: For **erasure** pools only. Use the `erasure code profile`_. It
|
|
must be an existing profile as defined by
|
|
**osd erasure-code-profile set**.
|
|
|
|
:Type: String
|
|
:Required: No.
|
|
|
|
When you create a pool, set the number of placement groups to a reasonable value
|
|
(e.g., ``100``). Consider the total number of placement groups per OSD too.
|
|
Placement groups are computationally expensive, so performance will degrade when
|
|
you have many pools with many placement groups (e.g., 50 pools with 100
|
|
placement groups each). The point of diminishing returns depends upon the power
|
|
of the OSD host.
|
|
|
|
See `Placement Groups`_ for details on calculating an appropriate number of
|
|
placement groups for your pool.
|
|
|
|
.. _Placement Groups: ../placement-groups
|
|
|
|
``[expected-num-objects]``
|
|
|
|
:Description: The expected number of objects for this pool. By setting this value (
|
|
together with a negative **filestore merge threshold**), the PG folder
|
|
splitting would happen at the pool creation time, to avoid the latency
|
|
impact to do a runtime folder splitting.
|
|
|
|
:Type: Integer
|
|
:Required: No.
|
|
:Default: 0, no splitting at the pool creation time.
|
|
|
|
Set Pool Quotas
|
|
===============
|
|
|
|
You can set pool quotas for the maximum number of bytes and/or the maximum
|
|
number of objects per pool. ::
|
|
|
|
ceph osd pool set-quota {pool-name} [max_objects {obj-count}] [max_bytes {bytes}]
|
|
|
|
For example::
|
|
|
|
ceph osd pool set-quota data max_objects 10000
|
|
|
|
To remove a quota, set its value to ``0``.
|
|
|
|
|
|
Delete a Pool
|
|
=============
|
|
|
|
To delete a pool, execute::
|
|
|
|
ceph osd pool delete {pool-name} [{pool-name} --yes-i-really-really-mean-it]
|
|
|
|
|
|
If you created your own rulesets and rules for a pool you created, you should
|
|
consider removing them when you no longer need your pool. If you created users
|
|
with permissions strictly for a pool that no longer exists, you should consider
|
|
deleting those users too.
|
|
|
|
|
|
Rename a Pool
|
|
=============
|
|
|
|
To rename a pool, execute::
|
|
|
|
ceph osd pool rename {current-pool-name} {new-pool-name}
|
|
|
|
If you rename a pool and you have per-pool capabilities for an authenticated
|
|
user, you must update the user's capabilities (i.e., caps) with the new pool
|
|
name.
|
|
|
|
.. note:: Version ``0.48`` Argonaut and above.
|
|
|
|
Show Pool Statistics
|
|
====================
|
|
|
|
To show a pool's utilization statistics, execute::
|
|
|
|
rados df
|
|
|
|
|
|
Make a Snapshot of a Pool
|
|
=========================
|
|
|
|
To make a snapshot of a pool, execute::
|
|
|
|
ceph osd pool mksnap {pool-name} {snap-name}
|
|
|
|
.. note:: Version ``0.48`` Argonaut and above.
|
|
|
|
|
|
Remove a Snapshot of a Pool
|
|
===========================
|
|
|
|
To remove a snapshot of a pool, execute::
|
|
|
|
ceph osd pool rmsnap {pool-name} {snap-name}
|
|
|
|
.. note:: Version ``0.48`` Argonaut and above.
|
|
|
|
.. _setpoolvalues:
|
|
|
|
|
|
Set Pool Values
|
|
===============
|
|
|
|
To set a value to a pool, execute the following::
|
|
|
|
ceph osd pool set {pool-name} {key} {value}
|
|
|
|
You may set values for the following keys:
|
|
|
|
.. _size:
|
|
|
|
``size``
|
|
|
|
:Description: Sets the number of replicas for objects in the pool.
|
|
See `Set the Number of Object Replicas`_ for further details.
|
|
Replicated pools only.
|
|
|
|
:Type: Integer
|
|
|
|
.. _min_size:
|
|
|
|
``min_size``
|
|
|
|
:Description: Sets the minimum number of replicas required for I/O.
|
|
See `Set the Number of Object Replicas`_ for further details.
|
|
Replicated pools only.
|
|
|
|
:Type: Integer
|
|
:Version: ``0.54`` and above
|
|
|
|
.. _crash_replay_interval:
|
|
|
|
``crash_replay_interval``
|
|
|
|
:Description: The number of seconds to allow clients to replay acknowledged,
|
|
but uncommitted requests.
|
|
|
|
:Type: Integer
|
|
|
|
.. _pgp_num:
|
|
|
|
``pgp_num``
|
|
|
|
:Description: The effective number of placement groups to use when calculating
|
|
data placement.
|
|
|
|
:Type: Integer
|
|
:Valid Range: Equal to or less than ``pg_num``.
|
|
|
|
.. _crush_ruleset:
|
|
|
|
``crush_ruleset``
|
|
|
|
:Description: The ruleset to use for mapping object placement in the cluster.
|
|
:Type: Integer
|
|
|
|
.. _hashpspool:
|
|
|
|
``hashpspool``
|
|
|
|
:Description: Set/Unset HASHPSPOOL flag on a given pool.
|
|
:Type: Integer
|
|
:Valid Range: 1 sets flag, 0 unsets flag
|
|
:Version: Version ``0.48`` Argonaut and above.
|
|
|
|
.. _nodelete:
|
|
|
|
``nodelete``
|
|
|
|
:Description: Set/Unset NODELETE flag on a given pool.
|
|
:Type: Integer
|
|
:Valid Range: 1 sets flag, 0 unsets flag
|
|
:Version: Version ``FIXME``
|
|
|
|
.. _nopgchange:
|
|
|
|
``nopgchange``
|
|
|
|
:Description: Set/Unset NOPGCHANGE flag on a given pool.
|
|
:Type: Integer
|
|
:Valid Range: 1 sets flag, 0 unsets flag
|
|
:Version: Version ``FIXME``
|
|
|
|
.. _nosizechange:
|
|
|
|
``nosizechange``
|
|
|
|
:Description: Set/Unset NOSIZECHANGE flag on a given pool.
|
|
:Type: Integer
|
|
:Valid Range: 1 sets flag, 0 unsets flag
|
|
:Version: Version ``FIXME``
|
|
|
|
.. _write_fadvise_dontneed:
|
|
|
|
``write_fadvise_dontneed``
|
|
|
|
:Description: Set/Unset WRITE_FADVISE_DONTNEED flag on a given pool.
|
|
:Type: Integer
|
|
:Valid Range: 1 sets flag, 0 unsets flag
|
|
|
|
.. _noscrub:
|
|
|
|
``noscrub``
|
|
|
|
:Description: Set/Unset NOSCRUB flag on a given pool.
|
|
:Type: Integer
|
|
:Valid Range: 1 sets flag, 0 unsets flag
|
|
|
|
.. _nodeep-scrub:
|
|
|
|
``nodeep-scrub``
|
|
|
|
:Description: Set/Unset NODEEP_SCRUB flag on a given pool.
|
|
:Type: Integer
|
|
:Valid Range: 1 sets flag, 0 unsets flag
|
|
|
|
.. _hit_set_type:
|
|
|
|
``hit_set_type``
|
|
|
|
:Description: Enables hit set tracking for cache pools.
|
|
See `Bloom Filter`_ for additional information.
|
|
|
|
:Type: String
|
|
:Valid Settings: ``bloom``, ``explicit_hash``, ``explicit_object``
|
|
:Default: ``bloom``. Other values are for testing.
|
|
|
|
.. _hit_set_count:
|
|
|
|
``hit_set_count``
|
|
|
|
:Description: The number of hit sets to store for cache pools. The higher
|
|
the number, the more RAM consumed by the ``ceph-osd`` daemon.
|
|
|
|
:Type: Integer
|
|
:Valid Range: ``1``. Agent doesn't handle > 1 yet.
|
|
|
|
.. _hit_set_period:
|
|
|
|
``hit_set_period``
|
|
|
|
:Description: The duration of a hit set period in seconds for cache pools.
|
|
The higher the number, the more RAM consumed by the
|
|
``ceph-osd`` daemon.
|
|
|
|
:Type: Integer
|
|
:Example: ``3600`` 1hr
|
|
|
|
.. _hit_set_fpp:
|
|
|
|
``hit_set_fpp``
|
|
|
|
:Description: The false positive probability for the ``bloom`` hit set type.
|
|
See `Bloom Filter`_ for additional information.
|
|
|
|
:Type: Double
|
|
:Valid Range: 0.0 - 1.0
|
|
:Default: ``0.05``
|
|
|
|
.. _cache_target_dirty_ratio:
|
|
|
|
``cache_target_dirty_ratio``
|
|
|
|
:Description: The percentage of the cache pool containing modified (dirty)
|
|
objects before the cache tiering agent will flush them to the
|
|
backing storage pool.
|
|
|
|
:Type: Double
|
|
:Default: ``.4``
|
|
|
|
.. _cache_target_dirty_high_ratio:
|
|
|
|
``cache_target_dirty_high_ratio``
|
|
|
|
:Description: The percentage of the cache pool containing modified (dirty)
|
|
objects before the cache tiering agent will flush them to the
|
|
backing storage pool with a higher speed.
|
|
|
|
:Type: Double
|
|
:Default: ``.6``
|
|
|
|
.. _cache_target_full_ratio:
|
|
|
|
``cache_target_full_ratio``
|
|
|
|
:Description: The percentage of the cache pool containing unmodified (clean)
|
|
objects before the cache tiering agent will evict them from the
|
|
cache pool.
|
|
|
|
:Type: Double
|
|
:Default: ``.8``
|
|
|
|
.. _target_max_bytes:
|
|
|
|
``target_max_bytes``
|
|
|
|
:Description: Ceph will begin flushing or evicting objects when the
|
|
``max_bytes`` threshold is triggered.
|
|
|
|
:Type: Integer
|
|
:Example: ``1000000000000`` #1-TB
|
|
|
|
.. _target_max_objects:
|
|
|
|
``target_max_objects``
|
|
|
|
:Description: Ceph will begin flushing or evicting objects when the
|
|
``max_objects`` threshold is triggered.
|
|
|
|
:Type: Integer
|
|
:Example: ``1000000`` #1M objects
|
|
|
|
|
|
``hit_set_grade_decay_rate``
|
|
|
|
:Description: Temperature decay rate between two successive hit_sets
|
|
:Type: Integer
|
|
:Valid Range: 0 - 100
|
|
:Default: ``20``
|
|
|
|
|
|
``hit_set_grade_search_last_n``
|
|
|
|
:Description: Count at most N appearance in hit_sets for temperature calculation
|
|
:Type: Integer
|
|
:Valid Range: 0 - hit_set_count
|
|
:Default: ``1``
|
|
|
|
|
|
.. _cache_min_flush_age:
|
|
|
|
``cache_min_flush_age``
|
|
|
|
:Description: The time (in seconds) before the cache tiering agent will flush
|
|
an object from the cache pool to the storage pool.
|
|
|
|
:Type: Integer
|
|
:Example: ``600`` 10min
|
|
|
|
.. _cache_min_evict_age:
|
|
|
|
``cache_min_evict_age``
|
|
|
|
:Description: The time (in seconds) before the cache tiering agent will evict
|
|
an object from the cache pool.
|
|
|
|
:Type: Integer
|
|
:Example: ``1800`` 30min
|
|
|
|
.. _fast_read:
|
|
|
|
``fast_read``
|
|
|
|
:Description: On Erasure Coding pool, if this flag is turned on, the read request
|
|
would issue sub reads to all shards, and wait until it receives enough
|
|
shards to decode to serve the client. In the case of jerasure and isa
|
|
erasure plugins, once the first K replies return, client's request is
|
|
serverd immediately using the data decoded from these replies. This
|
|
helps to tradeoff some resources for betterperformance. Currently this
|
|
flag is only supported for Erasure Coding pool.
|
|
|
|
:Type: Boolean
|
|
:Defaults: ``0``
|
|
|
|
.. _scrub_min_interval:
|
|
|
|
``scrub_min_interval``
|
|
|
|
:Description: The maximum interval in seconds for pool scrubbing when
|
|
load is low. If it is 0, the value osd_scrub_min_interval
|
|
from config is used.
|
|
|
|
:Type: Double
|
|
:Default: ``0``
|
|
|
|
.. _scrub_max_interval:
|
|
|
|
``scrub_max_interval``
|
|
|
|
:Description: The maximum interval in seconds for pool scrubbing
|
|
irrespective of cluster load. If it is 0, the value
|
|
osd_scrub_max_interval from config is used.
|
|
|
|
:Type: Double
|
|
:Default: ``0``
|
|
|
|
.. _deep_scrub_interval:
|
|
|
|
``deep_scrub_interval``
|
|
|
|
:Description: The interval in seconds for pool “deep” scrubbing. If it
|
|
is 0, the value osd_deep_scrub_interval from config is used.
|
|
|
|
:Type: Double
|
|
:Default: ``0``
|
|
|
|
|
|
Get Pool Values
|
|
===============
|
|
|
|
To get a value from a pool, execute the following::
|
|
|
|
ceph osd pool get {pool-name} {key}
|
|
|
|
You may get values for the following keys:
|
|
|
|
``size``
|
|
|
|
:Description: see size_
|
|
|
|
:Type: Integer
|
|
|
|
``min_size``
|
|
|
|
:Description: see min_size_
|
|
|
|
:Type: Integer
|
|
:Version: ``0.54`` and above
|
|
|
|
``crash_replay_interval``
|
|
|
|
:Description: see crash_replay_interval_
|
|
|
|
:Type: Integer
|
|
|
|
|
|
``pgp_num``
|
|
|
|
:Description: see pgp_num_
|
|
|
|
:Type: Integer
|
|
:Valid Range: Equal to or less than ``pg_num``.
|
|
|
|
|
|
``crush_ruleset``
|
|
|
|
:Description: see crush_ruleset_
|
|
|
|
|
|
``hit_set_type``
|
|
|
|
:Description: see hit_set_type_
|
|
|
|
:Type: String
|
|
:Valid Settings: ``bloom``, ``explicit_hash``, ``explicit_object``
|
|
|
|
``hit_set_count``
|
|
|
|
:Description: see hit_set_count_
|
|
|
|
:Type: Integer
|
|
|
|
|
|
``hit_set_period``
|
|
|
|
:Description: see hit_set_period_
|
|
|
|
:Type: Integer
|
|
|
|
|
|
``hit_set_fpp``
|
|
|
|
:Description: see hit_set_fpp_
|
|
|
|
:Type: Double
|
|
|
|
|
|
``cache_target_dirty_ratio``
|
|
|
|
:Description: see cache_target_dirty_ratio_
|
|
|
|
:Type: Double
|
|
|
|
|
|
``cache_target_dirty_high_ratio``
|
|
|
|
:Description: see cache_target_dirty_high_ratio_
|
|
|
|
:Type: Double
|
|
|
|
|
|
``cache_target_full_ratio``
|
|
|
|
:Description: see cache_target_full_ratio_
|
|
|
|
:Type: Double
|
|
|
|
|
|
``target_max_bytes``
|
|
|
|
:Description: see target_max_bytes_
|
|
|
|
:Type: Integer
|
|
|
|
|
|
``target_max_objects``
|
|
|
|
:Description: see target_max_objects_
|
|
|
|
:Type: Integer
|
|
|
|
|
|
``cache_min_flush_age``
|
|
|
|
:Description: see cache_min_flush_age_
|
|
|
|
:Type: Integer
|
|
|
|
|
|
``cache_min_evict_age``
|
|
|
|
:Description: see cache_min_evict_age_
|
|
|
|
:Type: Integer
|
|
|
|
|
|
``fast_read``
|
|
|
|
:Description: see fast_read_
|
|
|
|
:Type: Boolean
|
|
|
|
|
|
``scrub_min_interval``
|
|
|
|
:Description: see scrub_min_interval_
|
|
|
|
:Type: Double
|
|
|
|
|
|
``scrub_max_interval``
|
|
|
|
:Description: see scrub_max_interval_
|
|
|
|
:Type: Double
|
|
|
|
|
|
``deep_scrub_interval``
|
|
|
|
:Description: see deep_scrub_interval_
|
|
|
|
:Type: Double
|
|
|
|
|
|
Set the Number of Object Replicas
|
|
=================================
|
|
|
|
To set the number of object replicas on a replicated pool, execute the following::
|
|
|
|
ceph osd pool set {poolname} size {num-replicas}
|
|
|
|
.. important:: The ``{num-replicas}`` includes the object itself.
|
|
If you want the object and two copies of the object for a total of
|
|
three instances of the object, specify ``3``.
|
|
|
|
For example::
|
|
|
|
ceph osd pool set data size 3
|
|
|
|
You may execute this command for each pool. **Note:** An object might accept
|
|
I/Os in degraded mode with fewer than ``pool size`` replicas. To set a minimum
|
|
number of required replicas for I/O, you should use the ``min_size`` setting.
|
|
For example::
|
|
|
|
ceph osd pool set data min_size 2
|
|
|
|
This ensures that no object in the data pool will receive I/O with fewer than
|
|
``min_size`` replicas.
|
|
|
|
|
|
Get the Number of Object Replicas
|
|
=================================
|
|
|
|
To get the number of object replicas, execute the following::
|
|
|
|
ceph osd dump | grep 'replicated size'
|
|
|
|
Ceph will list the pools, with the ``replicated size`` attribute highlighted.
|
|
By default, ceph Creates two replicas of an object (a total of three copies, or
|
|
a size of 3).
|
|
|
|
|
|
|
|
.. _Pool, PG and CRUSH Config Reference: ../../configuration/pool-pg-config-ref
|
|
.. _Bloom Filter: http://en.wikipedia.org/wiki/Bloom_filter
|
|
.. _setting the number of placement groups: ../placement-groups#set-the-number-of-placement-groups
|