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Administration Guide / Operating a Cluster / Managing Storage Pools
Applies to SUSE Enterprise Storage 6

22 Managing Storage Pools

Ceph stores data within pools. Pools are logical groups for storing objects. When you first deploy a cluster without creating a pool, Ceph uses the default pools for storing data. The following important highlights relate to Ceph pools:

  • Resilience: You can set how many OSDs, buckets, or leaves are allowed to fail without losing data. For replicated pools, it is the desired number of copies/replicas of an object. New pools are created with a default count of replicas set to 3. For erasure coded pools, it is the number of coding chunks (that is m=2 in the erasure code profile).

  • Placement Groups: are internal data structures for storing data in a pool across OSDs. The way Ceph stores data into PGs is defined in a CRUSH Map. You can set the number of placement groups for a pool at its creation. 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, objects and its replicas (or chunks in case of erasure coded pools) are placed according to the CRUSH ruleset mapped to the pool. 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.

To organize data into pools, you can list, create, and remove pools. You can also view the usage statistics for each pool.

22.1 Associate Pools with an Application

Before using pools, you need to associate them with an application. Pools that will be used with CephFS, or pools that are automatically created by Object Gateway are automatically associated.

For other cases, you can manually associate a free-form application name with a pool: 

cephadm@adm > ceph osd pool application enable pool_name application_name
Tip
Tip: Default Application Names

CephFS uses the application name cephfs, RADOS Block Device uses rbd, and Object Gateway uses rgw.

A pool can be associated with multiple applications, and each application can have its own metadata. You can display the application metadata for a given pool using the following command: 

cephadm@adm > ceph osd pool application get pool_name

22.2 Operating Pools

This section introduces practical information to perform basic tasks with pools. You can find out how to list, create, and delete pools, as well as show pool statistics or manage snapshots of a pool.

22.2.1 List Pools

To list your cluster’s pools, execute: 

cephadm@adm > ceph osd pool ls

22.2.2 Create a Pool

A pool can be created as either 'replicated' to recover from lost OSDs by keeping multiple copies of the objects or 'erasure' to get a kind of generalized RAID5/6 capability. Replicated pools require more raw storage, while erasure coded pools require less raw storage. Default is 'replicated'.

To create a replicated pool, execute: 

cephadm@adm > ceph osd pool create pool_name pg_num pgp_num replicated crush_ruleset_name \
expected_num_objects

To create an erasure coded pool, execute: 

cephadm@adm > ceph osd pool create pool_name pg_num pgp_num erasure erasure_code_profile \
 crush_ruleset_name expected_num_objects

The ceph osd pool create can fail if you exceed the limit of placement groups per OSD. The limit is set with the option mon_max_pg_per_osd.

pool_name

The name of the pool. It must be unique. This option is required.

pg_num

The total number of placement groups for the pool. This option is required. Default value is 8.

pgp_num

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. This option is required. Default value is 8.

crush_ruleset_name

The name of the crush ruleset for this pool. If the specified ruleset does not exist, the creation of replicated pools will fail with -ENOENT. For replicated pools it is the ruleset specified by the osd pool default crush replicated ruleset configuration 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 does not exist already.

erasure_code_profile=profile

For erasure coded pools only. Use the erasure code profile. It must be an existing profile as defined by osd erasure-code-profile set.

When you create a pool, set the number of placement groups to a reasonable value. 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 (for example 50 pools with 100 placement groups each).

See Section 20.4, “Placement Groups” for details on calculating an appropriate number of placement groups for your pool.

expected_num_objects

The expected number of objects for this pool. By setting this value (together with a negative filestore merge threshold), the PG folder splitting happens at the pool creation time. This avoids the latency impact with a runtime folder splitting.

22.2.3 Set Pool Quotas

You can set pool quotas for the maximum number of bytes and/or the maximum number of objects per pool. 

cephadm@adm > ceph osd pool set-quota pool-name max_objects obj-count max_bytes bytes

For example: 

cephadm@adm > ceph osd pool set-quota data max_objects 10000

To remove a quota, set its value to 0.

22.2.4 Delete a Pool

Warning
Warning: Pool Deletion is Not Reversible

Pools may contain important data. Deleting a pool causes all data in the pool to disappear, and there is no way to recover it.

Because inadvertent pool deletion is a real danger, Ceph implements two mechanisms that prevent pools from being deleted. Both mechanisms must be disabled before a pool can be deleted.

The first mechanism is the NODELETE flag. Each pool has this flag, and its default value is 'false'. To find out the value of this flag on a pool, run the following command: 

cephadm@adm > ceph osd pool get pool_name nodelete

If it outputs nodelete: true, it is not possible to delete the pool until you change the flag using the following command: 

cephadm@adm > ceph osd pool set pool_name nodelete false

The second mechanism is the cluster-wide configuration parameter mon allow pool delete, which defaults to 'false'. This means that, by default, it is not possible to delete a pool. The error message displayed is: 

Error EPERM: pool deletion is disabled; you must first set the
mon_allow_pool_delete config option to true before you can destroy a pool

To delete the pool in spite of this safety setting, you can temporarily set mon allow pool delete to 'true', delete the pool, and then return the parameter to 'false': 

cephadm@adm > ceph tell mon.* injectargs --mon-allow-pool-delete=true
cephadm@adm > ceph osd pool delete pool_name pool_name --yes-i-really-really-mean-it
cephadm@adm > ceph tell mon.* injectargs --mon-allow-pool-delete=false

The injectargs command displays the following message: 

injectargs:mon_allow_pool_delete = 'true' (not observed, change may require restart)

This is merely confirming that the command was executed successfully. It is not an error.

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.

22.2.5 Rename a Pool

To rename a pool, execute: 

cephadm@adm > 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 with the new pool name.

22.2.6 Show Pool Statistics

To show a pool’s usage statistics, execute: 

cephadm@adm > rados df
POOL_NAME                    USED OBJECTS CLONES COPIES MISSING_ON_PRIMARY UNFOUND DEGRADED  RD_OPS      RD  WR_OPS      WR USED COMPR UNDER COMPR
.rgw.root                 768 KiB       4      0     12                  0       0        0      44  44 KiB       4   4 KiB        0 B         0 B
cephfs_data               960 KiB       5      0     15                  0       0        0    5502 2.1 MiB      14  11 KiB        0 B         0 B
cephfs_metadata           1.5 MiB      22      0     66                  0       0        0      26  78 KiB     176 147 KiB        0 B         0 B
default.rgw.buckets.index     0 B       1      0      3                  0       0        0       4   4 KiB       1     0 B        0 B         0 B
default.rgw.control           0 B       8      0     24                  0       0        0       0     0 B       0     0 B        0 B         0 B
default.rgw.log               0 B     207      0    621                  0       0        0 5372132 5.1 GiB 3579618     0 B        0 B         0 B
default.rgw.meta          961 KiB       6      0     18                  0       0        0     155 140 KiB      14   7 KiB        0 B         0 B
example_rbd_pool          2.1 MiB      18      0     54                  0       0        0 3350841 2.7 GiB     118  98 KiB        0 B         0 B
iscsi-images              769 KiB       8      0     24                  0       0        0 1559261 1.3 GiB      61  42 KiB        0 B         0 B
mirrored-pool             1.1 MiB      10      0     30                  0       0        0  475724 395 MiB      54  48 KiB        0 B         0 B
pool2                         0 B       0      0      0                  0       0        0       0     0 B       0     0 B        0 B         0 B
pool3                     333 MiB      37      0    111                  0       0        0 3169308 2.5 GiB   14847 118 MiB        0 B         0 B
pool4                     1.1 MiB      13      0     39                  0       0        0 1379568 1.1 GiB   16840  16 MiB        0 B         0 B

A description of individual columns follow:

USED

Number of bytes used by the pool.

OBJECTS

Number of objects stored in the pool.

CLONES

Number of clones stored in the pool. When a snapshot is created and one writes to an object, instead of modifying the original object its clone is created so the original snapshotted object content is not modified.

COPIES

Number of object replicas. For example, if a replicated pool with the replication factor 3 has 'x' objects, it will normally have 3 * x copies.

MISSING_ON_PRIMARY

Number of objects in the degraded state (not all copies exist) while the copy is missing on the primary OSD.

UNFOUND

Number of unfound objects.

DEGRADED

Number of degraded objects.

RD_OPS

Total number of read operations requested for this pool.

RD

Total number of bytes read from this pool.

WR_OPS

Total number of write operations requested for this pool.

WR

Total number of bytes written to the pool. Note that it is not the same as the pool's usage because you can write to the same object many times. The result is that the pool's usage will remain the same but the number of bytes written to the pool will grow.

USED COMPR

Number of bytes allocated for compressed data.

UNDER COMPR

Number of bytes that the compressed data occupy when it is not compressed.

22.2.7 Get Pool Values

To get a value from a pool, execute: 

cephadm@adm > ceph osd pool get pool-name key

You can get values for keys listed in Section 22.2.8, “Set Pool Values” plus the following keys:

pg_num

The number of placement groups for the pool.

pgp_num

The effective number of placement groups to use when calculating data placement. Valid range is equal to or less than pg_num.

Tip
Tip: All of a Pool's Values

To list all values related to a specific pool, run: 

cephadm@adm > ceph osd pool get POOL_NAME all

22.2.8 Set Pool Values

To set a value to a pool, execute: 

cephadm@adm > ceph osd pool set pool-name KEY VALUE

The following is a list of pool values sorted by a pool type:

Common Pool Values
crash_replay_interval

The number of seconds to allow clients to replay acknowledged, but uncommitted requests.

pg_num

The number of placement groups for the pool. If you add new OSDs to the cluster, verify the value for placement groups on all pools targeted for the new OSDs.

pgp_num

The effective number of placement groups to use when calculating data placement.

crush_ruleset

The ruleset to use for mapping object placement in the cluster.

hashpspool

Set (1) or unset (0) the HASHPSPOOL flag on a given pool. Enabling this flag changes the algorithm to better distribute PGs to OSDs. After enabling this flag on a pool whose HASHPSPOOL flag was set to the default 0, the cluster starts backfilling to have a correct placement of all PGs again. Be aware that this can create quite substantial I/O load on a cluster, therefore do not enable the flag from 0 to 1 on highly loaded production clusters.

nodelete

Prevents the pool from being removed.

nopgchange

Prevents the pool's pg_num and pgp_num from being changed.

noscrub,nodeep-scrub

Disables (deep) scrubbing of the data for the specific pool to resolve temporary high I/O load.

write_fadvise_dontneed

Set or unset the WRITE_FADVISE_DONTNEED flag on a given pool's read/write requests to bypass putting data into cache. Default is false. Applies to both replicated and EC pools.

scrub_min_interval

The minimum interval in seconds for pool scrubbing when the cluster load is low. The default 0 means that the osd_scrub_min_interval value from the Ceph configuration file is used.

scrub_max_interval

The maximum interval in seconds for pool scrubbing, regardless of the cluster load. The default 0 means that the osd_scrub_max_interval value from the Ceph configuration file is used.

deep_scrub_interval

The interval in seconds for the pool deep scrubbing. The default 0 means that the osd_deep_scrub value from the Ceph configuration file is used.

Replicated Pool Values
size

Sets the number of replicas for objects in the pool. See Section 22.2.9, “Set the Number of Object Replicas” for further details. Replicated pools only.

min_size

Sets the minimum number of replicas required for I/O. See Section 22.2.9, “Set the Number of Object Replicas” for further details. Replicated pools only.

nosizechange

Prevents the pool's size from being changed. When a pool is created, the default value is taken from the value of the osd_pool_default_flag_nosizechange parameter which is false by default. Applies to replicated pools only because you cannot change size for EC pools.

hit_set_type

Enables hit set tracking for cache pools. See Bloom Filter for additional information. This option can have the following values: bloom, explicit_hash, explicit_object. Default is bloom, other values are for testing only.

hit_set_count

The number of hit sets to store for cache pools. The higher the number, the more RAM consumed by the ceph-osd daemon. Default is 0.

hit_set_period

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. When a pool is created, the default value is taken from the value of the osd_tier_default_cache_hit_set_period parameter, which is 1200 by default. Applies to replicated pools only because EC pools cannot be used as a cache tier.

hit_set_fpp

The false positive probability for the bloom hit set type. See Bloom Filter for additional information. Valid range is 0.0 - 1.0 Default is 0.05

use_gmt_hitset

Force OSDs to use GMT (Greenwich Mean Time) time stamps when creating a hit set for cache tiering. This ensures that nodes in different time zones return the same result. Default is 1. This value should not be changed.

cache_target_dirty_ratio

The percentage of the cache pool containing modified (dirty) objects before the cache tiering agent will flush them to the backing storage pool. Default is 0.4.

cache_target_dirty_high_ratio

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. Default is 0.6.

cache_target_full_ratio

The percentage of the cache pool containing unmodified (clean) objects before the cache tiering agent will evict them from the cache pool. Default is 0.8.

target_max_bytes

Ceph will begin flushing or evicting objects when the max_bytes threshold is triggered.

target_max_objects

Ceph will begin flushing or evicting objects when the max_objects threshold is triggered.

hit_set_grade_decay_rate

Temperature decay rate between two successive hit_sets. Default is 20.

hit_set_search_last_n

Count at most N appearances in hit_sets for temperature calculation. Default is 1.

cache_min_flush_age

The time (in seconds) before the cache tiering agent will flush an object from the cache pool to the storage pool.

cache_min_evict_age

The time (in seconds) before the cache tiering agent will evict an object from the cache pool.

Erasure Coded Pool Values
fast_read

If this flag is enabled on erasure coding pools, then the read request issues sub-reads to all shards, and waits until it receives enough shards to decode to serve the client. In the case of jerasure and isa erasure plug-ins, when the first K replies return, then the client’s request is served immediately using the data decoded from these replies. This approach causes more CPU load and less disk/network load. Currently, this flag is only supported for erasure coding pools. Default is 0.

22.2.9 Set the Number of Object Replicas

To set the number of object replicas on a replicated pool, execute the following: 

cephadm@adm > ceph osd pool set poolname size num-replicas

The num-replicas includes the object itself. For example if you want the object and two copies of the object for a total of three instances of the object, specify 3.

Warning
Warning: Do Not Set Less Than 3 Replicas

If you set the num-replicas to 2, there will be only one copy of your data. If you lose one object instance, you need to trust that the other copy has not been corrupted, for example since the last scrubbing during recovery (refer to Section 20.6, “Scrubbing” for details).

Setting a pool to one replica means that there is exactly one instance of the data object in the pool. If the OSD fails, you lose the data. A possible usage for a pool with one replica is storing temporary data for a short time.

Tip
Tip: Setting More Than 3 Replicas

Setting 4 replicas for a pool increases the reliability by 25%.

In case of two data centers, you need to set at least 4 replicas for a pool to have two copies in each data center so that if one data center is lost, two copies still exist and you can still lose one disk without losing data.

Note
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: 

cephadm@adm > 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.

Tip
Tip: Get the Number of Object Replicas

To get the number of object replicas, execute the following: 

cephadm@adm > 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).

22.3 Pool Migration

When creating a pool (see Section 22.2.2, “Create a Pool”) you need to specify its initial parameters, such as the pool type or the number of placement groups. If you later decide to change any of these parameters—for example when converting a replicated pool into an erasure coded one, or decreasing the number of placement groups—you need to migrate the pool data to another one whose parameters suit your deployment.

This section describes two migration methods—a cache tier method for general pool data migration, and a method using rbd migrate sub-commands to migrate RBD images to a new pool. Each method has its specifics and limitations.

22.3.1 Limitations

  • You can use the cache tier method to migrate from a replicated pool to either an EC pool or another replicated pool. Migrating from an EC pool is not supported.

  • You cannot migrate RBD images and CephFS exports from a replicated pool to an EC pool. The reason is that EC pools do not support omap, while RBD and CephFS use omap to store its metadata. For example, the header object of the RBD will fail to be flushed. But you can migrate data to EC pool, leaving metadata in replicated pool.

  • The rbd migration method allows migrating images with minimal client downtime. You only need to stop the client before the prepare step and start it afterward. Note that only a librbd client that supports this feature (Ceph Nautilus or newer) will be able to open the image just after the prepare step, while older librbd clients or the krbd clients will not be able to open the image until the commit step is executed.

22.3.2 Migrate Using Cache Tier

The principle is simple—include the pool that you need to migrate into a cache tier in reverse order. Find more details on cache tiers in Book “Tuning Guide”, Chapter 7 “Cache Tiering”. The following example migrates a replicated pool named 'testpool' to an erasure coded pool:

Procedure 22.1: Migrating Replicated to Erasure Coded Pool

  1. Create a new erasure coded pool named 'newpool'. Refer to Section 22.2.2, “Create a Pool” for a detailed explanation of pool creation parameters. 

     cephadm@adm > ceph osd pool create newpool PG_NUM PGP_NUM erasure default

    Verify that the used client keyring provides at least the same capabilities for 'newpool' as it does for 'testpool'.

    Now you have two pools: the original replicated 'testpool' filled with data, and the new empty erasure coded 'newpool':

    Pools before Migration
    Figure 22.1: Pools before Migration

  2. Set up the cache tier and configure the replicated pool 'testpool' as a cache pool. The -force-nonempty option allows adding a cache tier even if the pool already has data: 

    cephadm@adm > ceph tell mon.* injectargs \
 '--mon_debug_unsafe_allow_tier_with_nonempty_snaps=1'
cephadm@adm > ceph osd tier add newpool testpool --force-nonempty
cephadm@adm > ceph osd tier cache-mode testpool proxy
    Cache Tier Setup
    Figure 22.2: Cache Tier Setup

  3. Force the cache pool to move all objects to the new pool: 

    cephadm@adm > rados -p testpool cache-flush-evict-all
    Data Flushing
    Figure 22.3: Data Flushing

  4. Until all the data has been flushed to the new erasure coded pool, you need to specify an overlay so that objects are searched on the old pool: 

    cephadm@adm > ceph osd tier set-overlay newpool testpool

    With the overlay, all operations are forwarded to the old replicated 'testpool':

    Setting Overlay
    Figure 22.4: Setting Overlay

    Now you can switch all the clients to access objects on the new pool.

  5. After all data is migrated to the erasure coded 'newpool', remove the overlay and the old cache pool 'testpool': 

    cephadm@adm > ceph osd tier remove-overlay newpool
cephadm@adm > ceph osd tier remove newpool testpool
    Migration Complete
    Figure 22.5: Migration Complete

  6. Run 

    cephadm@adm > ceph tell mon.* injectargs \
 '--mon_debug_unsafe_allow_tier_with_nonempty_snaps=0'

22.3.3 Migrating RBD Images

The following is the recommended way to migrate RBD images from one replicated pool to another replicated pool.

  1. Stop clients (such as a virtual machine) from accessing the RBD image.

  2. Create a new image in the target pool, with the parent set to the source image: 

    cephadm@adm > rbd migration prepare SRC_POOL/IMAGE TARGET_POOL/IMAGE
    Tip
    Tip: Migrate Only Data to an EC Pool

    If you need to migrate only the image data to a new EC pool and leave the metadata in the original replicated pool, run the following command instead: 

    cephadm@adm > rbd migration prepare SRC_METADATA_POOL/IMAGE TARGET_METADATA_POOL/IMAGE \
 --data-pool TARGET_DATA_POOL/IMAGE

  3. Let clients access the image in the target pool.

  4. Migrate data to the target pool: 

    cephadm@adm > rbd migration execute SRC_POOL/IMAGE

  5. Remove the old image: 

    cephadm@adm > rbd migration commit SRC_POOL/IMAGE

22.4 Pool Snapshots

Pool snapshots are snapshots of the state of the whole Ceph pool. With pool snapshots, you can retain the history of the pool's state. Creating pool snapshots consumes storage space proportional to the pool size. Always check the related storage for enough disk space before creating a snapshot of a pool.

22.4.1 Make a Snapshot of a Pool

To make a snapshot of a pool, run: 

cephadm@adm > ceph osd pool mksnap POOL-NAME SNAP-NAME

For example: 

cephadm@adm > ceph osd pool mksnap pool1 snap1
created pool pool1 snap snap1

22.4.2 List Snapshots of a Pool

To list existing snapshots of a pool, run: 

cephadm@adm > rados lssnap -p POOL_NAME

For example: 

cephadm@adm > rados lssnap -p pool1
1	snap1	2018.12.13 09:36:20
2	snap2	2018.12.13 09:46:03
2 snaps

22.4.3 Remove a Snapshot of a Pool

To remove a snapshot of a pool, run: 

cephadm@adm > ceph osd pool rmsnap POOL-NAME SNAP-NAME

22.5 Data Compression

BlueStore (find more details in Book “Deployment Guide”, Chapter 1 “SUSE Enterprise Storage 6 and Ceph”, Section 1.4 “BlueStore”) provides on-the-fly data compression to save disk space. The compression ratio depends on the data stored in the system. Note that compression/decompression requires additional CPU power.

You can configure data compression globally (see Section 22.5.3, “Global Compression Options”) and then override specific compression settings for each individual pool.

You can enable or disable pool data compression, or change the compression algorithm and mode at any time, regardless of whether the pool contains data or not.

No compression will be applied to existing data after enabling the pool compression.

After disabling the compression of a pool, all its data will be decompressed.

22.5.1 Enable Compression

To enable data compression for a pool named POOL_NAME, run the following command: 

cephadm@adm > ceph osd pool set POOL_NAME compression_algorithm COMPRESSION_ALGORITHM
cephadm@adm > ceph osd pool set POOL_NAME compression_mode COMPRESSION_MODE
Tip
Tip: Disabling Pool Compression

To disable data compression for a pool, use 'none' as the compression algorithm: 

cephadm@adm > ceph osd pool set POOL_NAME compression_algorithm none

22.5.2 Pool Compression Options

A full list of compression settings:

compression_algorithm

Possible values are none, zstd, snappy. Default is snappy.

Which compression algorithm to use depends on the specific use case. Several recommendations follow:

  • Use the default snappy as long as you do not have a good reason to change it.

  • zstd offers a good compression ratio, but causes high CPU overhead when compressing small amounts of data.

  • Run a benchmark of these algorithms on a sample of your actual data while keeping an eye on the CPU and memory usage of your cluster.

compression_mode

Possible values are none, aggressive, passive, force. Default is none.

  • none: compress never

  • passive: compress if hinted COMPRESSIBLE

  • aggressive: compress unless hinted INCOMPRESSIBLE

  • force: compress always

compression_required_ratio

Value: Double, Ratio = SIZE_COMPRESSED / SIZE_ORIGINAL. Default is 0.875, which means that if the compression does not reduce the occupied space by at least 12.5%, the object will not be compressed.

Objects above this ratio will not be stored compressed because of the low net gain.

compression_max_blob_size

Value: Unsigned Integer, size in bytes. Default: 0

Maximum size of objects that are compressed.

compression_min_blob_size

Value: Unsigned Integer, size in bytes. Default: 0

Minimum size of objects that are compressed.

22.5.3 Global Compression Options

The following configuration options can be set in the Ceph configuration and apply to all OSDs and not only a single pool. The pool specific configuration listed in Section 22.5.2, “Pool Compression Options” takes precedence.

bluestore_compression_algorithm

See compression_algorithm

bluestore_compression_mode

See compression_mode

bluestore_compression_required_ratio

See compression_required_ratio

bluestore_compression_min_blob_size

Value: Unsigned Integer, size in bytes. Default: 0

Minimum size of objects that are compressed. The setting is ignored by default in favor of bluestore_compression_min_blob_size_hdd and bluestore_compression_min_blob_size_ssd. It takes precedence when set to a non-zero value.

bluestore_compression_max_blob_size

Value: Unsigned Integer, size in bytes. Default: 0

Maximum size of objects that are compressed before they will be split into smaller chunks. The setting is ignored by default in favor of bluestore_compression_max_blob_size_hdd and bluestore_compression_max_blob_size_ssd. It takes precedence when set to a non-zero value.

bluestore_compression_min_blob_size_ssd

Value: Unsigned Integer, size in bytes. Default: 8K

Minimum size of objects that are compressed and stored on solid-state drive.

bluestore_compression_max_blob_size_ssd

Value: Unsigned Integer, size in bytes. Default: 64K

Maximum size of objects that are compressed and stored on solid-state drive before they will be split into smaller chunks.

bluestore_compression_min_blob_size_hdd

Value: Unsigned Integer, size in bytes. Default: 128K

Minimum size of objects that are compressed and stored on hard disks.

bluestore_compression_max_blob_size_hdd

Value: Unsigned Integer, size in bytes. Default: 512K

Maximum size of objects that are compressed and stored on hard disks before they will be split into smaller chunks.