Health checks¶

Overview¶

There is a finite set of health messages that a Ceph cluster can raise. These messages are known as health checks. Each health check has a unique identifier.

The identifier is a terse human-readable string – that is, the identifier is readable in much the same way as a typical variable name. It is intended to enable tools (for example, UIs) to make sense of health checks and present them in a way that reflects their meaning.

This page lists the health checks that are raised by the monitor and manager daemons. In addition to these, you might see health checks that originate from MDS daemons (see CephFS health messages), and health checks that are defined by ceph-mgr python modules.

Definitions¶

Monitor¶

DAEMON_OLD_VERSION¶

Warn if one or more old versions of Ceph are running on any daemons. A health check is raised if multiple versions are detected. This condition must exist for a period of time greater than mon_warn_older_version_delay (set to one week by default) in order for the health check to be raised. This allows most upgrades to proceed without the occurrence of a false warning. If the upgrade is paused for an extended time period, health mute can be used by running ceph health mute DAEMON_OLD_VERSION --sticky. Be sure, however, to run ceph health unmute DAEMON_OLD_VERSION after the upgrade has finished.

MON_DOWN¶

One or more monitor daemons are currently down. The cluster requires a majority (more than one-half) of the monitors to be available. When one or more monitors are down, clients might have a harder time forming their initial connection to the cluster, as they might need to try more addresses before they reach an operating monitor.

The down monitor daemon should be restarted as soon as possible to reduce the risk of a subsequent monitor failure leading to a service outage.

MON_CLOCK_SKEW¶

The clocks on the hosts running the ceph-mon monitor daemons are not well-synchronized. This health check is raised if the cluster detects a clock skew greater than mon_clock_drift_allowed.

This issue is best resolved by synchronizing the clocks by using a tool like ntpd or chrony.

If it is impractical to keep the clocks closely synchronized, the mon_clock_drift_allowed threshold can also be increased. However, this value must stay significantly below the mon_lease interval in order for the monitor cluster to function properly.

MON_MSGR2_NOT_ENABLED¶

The ms_bind_msgr2 option is enabled but one or more monitors are not configured to bind to a v2 port in the cluster’s monmap. This means that features specific to the msgr2 protocol (for example, encryption) are unavailable on some or all connections.

In most cases this can be corrected by running the following command:

ceph mon enable-msgr2

After this command is run, any monitor configured to listen on the old default port (6789) will continue to listen for v1 connections on 6789 and begin to listen for v2 connections on the new default port 3300.

If a monitor is configured to listen for v1 connections on a non-standard port (that is, a port other than 6789), then the monmap will need to be modified manually.

MON_DISK_LOW¶

One or more monitors are low on disk space. This health check is raised if the percentage of available space on the file system used by the monitor database (normally /var/lib/ceph/mon) drops below the percentage value mon_data_avail_warn (default: 30%).

This alert might indicate that some other process or user on the system is filling up the file system used by the monitor. It might also indicate that the monitor database is too large (see MON_DISK_BIG below).

If space cannot be freed, the monitor’s data directory might need to be moved to another storage device or file system (this relocation process must be carried out while the monitor daemon is not running).

MON_DISK_CRIT¶

One or more monitors are critically low on disk space. This health check is raised if the percentage of available space on the file system used by the monitor database (normally /var/lib/ceph/mon) drops below the percentage value mon_data_avail_crit (default: 5%). See MON_DISK_LOW, above.

MON_DISK_BIG¶

The database size for one or more monitors is very large. This health check is raised if the size of the monitor database is larger than mon_data_size_warn (default: 15 GiB).

A large database is unusual, but does not necessarily indicate a problem. Monitor databases might grow in size when there are placement groups that have not reached an active+clean state in a long time.

This alert might also indicate that the monitor’s database is not properly compacting, an issue that has been observed with some older versions of leveldb and rocksdb. Forcing a compaction with ceph daemon mon.<id> compact might shrink the database’s on-disk size.

This alert might also indicate that the monitor has a bug that prevents it from pruning the cluster metadata that it stores. If the problem persists, please report a bug.

To adjust the warning threshold, run the following command:

ceph config set global mon_data_size_warn <size>

AUTH_INSECURE_GLOBAL_ID_RECLAIM¶

One or more clients or daemons that are connected to the cluster are not securely reclaiming their global_id (a unique number that identifies each entity in the cluster) when reconnecting to a monitor. The client is being permitted to connect anyway because the auth_allow_insecure_global_id_reclaim option is set to true (which may be necessary until all Ceph clients have been upgraded) and because the auth_expose_insecure_global_id_reclaim option is set to true (which allows monitors to detect clients with “insecure reclaim” sooner by forcing those clients to reconnect immediately after their initial authentication).

To identify which client(s) are using unpatched Ceph client code, run the following command:

ceph health detail

If you collect a dump of the clients that are connected to an individual monitor and examine the global_id_status field in the output of the dump, you can see the global_id reclaim behavior of those clients. Here reclaim_insecure means that a client is unpatched and is contributing to this health check. To effect a client dump, run the following command:

ceph tell mon.\* sessions

We strongly recommend that all clients in the system be upgraded to a newer version of Ceph that correctly reclaims global_id values. After all clients have been updated, run the following command to stop allowing insecure reconnections:

ceph config set mon auth_allow_insecure_global_id_reclaim false

If it is impractical to upgrade all clients immediately, you can temporarily silence this alert by running the following command:

ceph health mute AUTH_INSECURE_GLOBAL_ID_RECLAIM 1w   # 1 week

Although we do NOT recommend doing so, you can also disable this alert indefinitely by running the following command:

ceph config set mon mon_warn_on_insecure_global_id_reclaim false

AUTH_INSECURE_GLOBAL_ID_RECLAIM_ALLOWED¶

Ceph is currently configured to allow clients that reconnect to monitors using an insecure process to reclaim their previous global_id. Such reclaiming is allowed because, by default, auth_allow_insecure_global_id_reclaim is set to true. It might be necessary to leave this setting enabled while existing Ceph clients are upgraded to newer versions of Ceph that correctly and securely reclaim their global_id.

If the AUTH_INSECURE_GLOBAL_ID_RECLAIM health check has not also been raised and if the auth_expose_insecure_global_id_reclaim setting has not been disabled (it is enabled by default), then there are currently no clients connected that need to be upgraded. In that case, it is safe to disable insecure global_id reclaim by running the following command:

ceph config set mon auth_allow_insecure_global_id_reclaim false

On the other hand, if there are still clients that need to be upgraded, then this alert can be temporarily silenced by running the following command:

ceph health mute AUTH_INSECURE_GLOBAL_ID_RECLAIM_ALLOWED 1w   # 1 week

Although we do NOT recommend doing so, you can also disable this alert indefinitely by running the following command:

ceph config set mon mon_warn_on_insecure_global_id_reclaim_allowed false

Manager¶

MGR_DOWN¶

All manager daemons are currently down. The cluster should normally have at least one running manager (ceph-mgr) daemon. If no manager daemon is running, the cluster’s ability to monitor itself will be compromised, and parts of the management API will become unavailable (for example, the dashboard will not work, and most CLI commands that report metrics or runtime state will block). However, the cluster will still be able to perform all I/O operations and to recover from failures.

The “down” manager daemon should be restarted as soon as possible to ensure that the cluster can be monitored (for example, so that the ceph -s information is up to date, or so that metrics can be scraped by Prometheus).

MGR_MODULE_DEPENDENCY¶

An enabled manager module is failing its dependency check. This health check typically comes with an explanatory message from the module about the problem.

For example, a module might report that a required package is not installed: in this case, you should install the required package and restart your manager daemons.

This health check is applied only to enabled modules. If a module is not enabled, you can see whether it is reporting dependency issues in the output of ceph module ls.

MGR_MODULE_ERROR¶

A manager module has experienced an unexpected error. Typically, this means that an unhandled exception was raised from the module’s serve function. The human-readable description of the error might be obscurely worded if the exception did not provide a useful description of itself.

This health check might indicate a bug: please open a Ceph bug report if you think you have encountered a bug.

However, if you believe the error is transient, you may restart your manager daemon(s) or use ceph mgr fail on the active daemon in order to force failover to another daemon.

OSDs¶

OSD_DOWN¶

One or more OSDs are marked “down”. The ceph-osd daemon might have been stopped, or peer OSDs might be unable to reach the OSD over the network. Common causes include a stopped or crashed daemon, a “down” host, or a network outage.

Verify that the host is healthy, the daemon is started, and the network is functioning. If the daemon has crashed, the daemon log file (/var/log/ceph/ceph-osd.*) might contain debugging information.

OSD_<crush type>_DOWN¶

(for example, OSD_HOST_DOWN, OSD_ROOT_DOWN)

All of the OSDs within a particular CRUSH subtree are marked “down” (for example, all OSDs on a host).

OSD_ORPHAN¶

An OSD is referenced in the CRUSH map hierarchy, but does not exist.

To remove the OSD from the CRUSH map hierarchy, run the following command:

ceph osd crush rm osd.<id>

OSD_OUT_OF_ORDER_FULL¶

The utilization thresholds for nearfull, backfillfull, full, and/or failsafe_full are not ascending. In particular, the following pattern is expected: nearfull < backfillfull, backfillfull < full, and full < failsafe_full.

To adjust these utilization thresholds, run the following commands:

ceph osd set-nearfull-ratio <ratio>
ceph osd set-backfillfull-ratio <ratio>
ceph osd set-full-ratio <ratio>

OSD_FULL¶

One or more OSDs have exceeded the full threshold and are preventing the cluster from servicing writes.

To check utilization by pool, run the following command:

ceph df

To see the currently defined full ratio, run the following command:

ceph osd dump | grep full_ratio

A short-term workaround to restore write availability is to raise the full threshold by a small amount. To do so, run the following command:

ceph osd set-full-ratio <ratio>

Additional OSDs should be deployed in order to add new storage to the cluster, or existing data should be deleted in order to free up space in the cluster.

OSD_BACKFILLFULL¶

One or more OSDs have exceeded the backfillfull threshold or would exceed it if the currently-mapped backfills were to finish, which will prevent data from rebalancing to this OSD. This alert is an early warning that rebalancing might be unable to complete and that the cluster is approaching full.

To check utilization by pool, run the following command:

ceph df

OSD_NEARFULL¶

One or more OSDs have exceeded the nearfull threshold. This alert is an early warning that the cluster is approaching full.

To check utilization by pool, run the following command:

ceph df

OSDMAP_FLAGS¶

One or more cluster flags of interest have been set. These flags include:

full - the cluster is flagged as full and cannot serve writes
pauserd, pausewr - there are paused reads or writes
noup - OSDs are not allowed to start
nodown - OSD failure reports are being ignored, and that means that the monitors will not mark OSDs “down”
noin - OSDs that were previously marked out are not being marked back in when they start
noout - “down” OSDs are not automatically being marked out after the configured interval
nobackfill, norecover, norebalance - recovery or data rebalancing is suspended
noscrub, nodeep_scrub - scrubbing is disabled
notieragent - cache-tiering activity is suspended

With the exception of full, these flags can be set or cleared by running the following commands:

ceph osd set <flag>
ceph osd unset <flag>

OSD_FLAGS¶

One or more OSDs or CRUSH {nodes,device classes} have a flag of interest set. These flags include:

noup: these OSDs are not allowed to start
nodown: failure reports for these OSDs will be ignored
noin: if these OSDs were previously marked out automatically after a failure, they will not be marked in when they start
noout: if these OSDs are “down” they will not automatically be marked out after the configured interval

To set and clear these flags in batch, run the following commands:

ceph osd set-group <flags> <who>
ceph osd unset-group <flags> <who>

For example:

ceph osd set-group noup,noout osd.0 osd.1
ceph osd unset-group noup,noout osd.0 osd.1
ceph osd set-group noup,noout host-foo
ceph osd unset-group noup,noout host-foo
ceph osd set-group noup,noout class-hdd
ceph osd unset-group noup,noout class-hdd

OLD_CRUSH_TUNABLES¶

The CRUSH map is using very old settings and should be updated. The oldest set of tunables that can be used (that is, the oldest client version that can connect to the cluster) without raising this health check is determined by the mon_crush_min_required_version config option. For more information, see Tunables.

OLD_CRUSH_STRAW_CALC_VERSION¶

The CRUSH map is using an older, non-optimal method of calculating intermediate weight values for straw buckets.

The CRUSH map should be updated to use the newer method (that is: straw_calc_version=1). For more information, see Tunables.

CACHE_POOL_NO_HIT_SET¶

One or more cache pools are not configured with a hit set to track utilization. This issue prevents the tiering agent from identifying cold objects that are to be flushed and evicted from the cache.

To configure hit sets on the cache pool, run the following commands:

ceph osd pool set <poolname> hit_set_type <type>
ceph osd pool set <poolname> hit_set_period <period-in-seconds>
ceph osd pool set <poolname> hit_set_count <number-of-hitsets>
ceph osd pool set <poolname> hit_set_fpp <target-false-positive-rate>

OSD_NO_SORTBITWISE¶

No pre-Luminous v12.y.z OSDs are running, but the sortbitwise flag has not been set.

The sortbitwise flag must be set in order for OSDs running Luminous v12.y.z or newer to start. To safely set the flag, run the following command:

ceph osd set sortbitwise

OSD_FILESTORE¶

Warn if OSDs are running Filestore. The Filestore OSD back end has been deprecated; the BlueStore back end has been the default object store since the Ceph Luminous release.

The ‘mclock_scheduler’ is not supported for Filestore OSDs. For this reason, the default ‘osd_op_queue’ is set to ‘wpq’ for Filestore OSDs and is enforced even if the user attempts to change it.

ceph report | jq -c '."osd_metadata" | .[] | select(.osd_objectstore | contains("filestore")) | {id, osd_objectstore}'

In order to upgrade to Reef or a later release, you must first migrate any Filestore OSDs to BlueStore.

If you are upgrading a pre-Reef release to Reef or later, but it is not feasible to migrate Filestore OSDs to BlueStore immediately, you can temporarily silence this alert by running the following command:

ceph health mute OSD_FILESTORE

Since this migration can take a considerable amount of time to complete, we recommend that you begin the process well in advance of any update to Reef or to later releases.

POOL_FULL¶

One or more pools have reached their quota and are no longer allowing writes.

To see pool quotas and utilization, run the following command:

ceph df detail

If you opt to raise the pool quota, run the following commands:

ceph osd pool set-quota <poolname> max_objects <num-objects>
ceph osd pool set-quota <poolname> max_bytes <num-bytes>

If not, delete some existing data to reduce utilization.

BLUEFS_SPILLOVER¶

One or more OSDs that use the BlueStore back end have been allocated db partitions (that is, storage space for metadata, normally on a faster device), but because that space has been filled, metadata has “spilled over” onto the slow device. This is not necessarily an error condition or even unexpected behavior, but may result in degraded performance. If the administrator had expected that all metadata would fit on the faster device, this alert indicates that not enough space was provided.

To disable this alert on all OSDs, run the following command:

ceph config set osd bluestore_warn_on_bluefs_spillover false

Alternatively, to disable the alert on a specific OSD, run the following command:

ceph config set osd.123 bluestore_warn_on_bluefs_spillover false

To secure more metadata space, you can destroy and reprovision the OSD in question. This process involves data migration and recovery.

It might also be possible to expand the LVM logical volume that backs the db storage. If the underlying LV has been expanded, you must stop the OSD daemon and inform BlueFS of the device-size change by running the following command:

ceph-bluestore-tool bluefs-bdev-expand --path /var/lib/ceph/osd/ceph-$ID

BLUEFS_AVAILABLE_SPACE¶

To see how much space is free for BlueFS, run the following command:

ceph daemon osd.123 bluestore bluefs available

This will output up to three values: BDEV_DB free, BDEV_SLOW free, and available_from_bluestore. BDEV_DB and BDEV_SLOW report the amount of space that has been acquired by BlueFS and is now considered free. The value available_from_bluestore indicates the ability of BlueStore to relinquish more space to BlueFS. It is normal for this value to differ from the amount of BlueStore free space, because the BlueFS allocation unit is typically larger than the BlueStore allocation unit. This means that only part of the BlueStore free space will be available for BlueFS.

BLUEFS_LOW_SPACE¶

If BlueFS is running low on available free space and there is not much free space available from BlueStore (in other words, available_from_bluestore has a low value), consider reducing the BlueFS allocation unit size. To simulate available space when the allocation unit is different, run the following command:

ceph daemon osd.123 bluestore bluefs available <alloc-unit-size>

BLUESTORE_FRAGMENTATION¶

As BlueStore operates, the free space on the underlying storage will become fragmented. This is normal and unavoidable, but excessive fragmentation causes slowdown. To inspect BlueStore fragmentation, run the following command:

ceph daemon osd.123 bluestore allocator score block

The fragmentation score is given in a [0-1] range. [0.0 .. 0.4] tiny fragmentation [0.4 .. 0.7] small, acceptable fragmentation [0.7 .. 0.9] considerable, but safe fragmentation [0.9 .. 1.0] severe fragmentation, might impact BlueFS’s ability to get space from BlueStore

To see a detailed report of free fragments, run the following command:

ceph daemon osd.123 bluestore allocator dump block

For OSD processes that are not currently running, fragmentation can be inspected with ceph-bluestore-tool. To see the fragmentation score, run the following command:

ceph-bluestore-tool --path /var/lib/ceph/osd/ceph-123 --allocator block free-score

To dump detailed free chunks, run the following command:

ceph-bluestore-tool --path /var/lib/ceph/osd/ceph-123 --allocator block free-dump

BLUESTORE_LEGACY_STATFS¶

One or more OSDs have BlueStore volumes that were created prior to the Nautilus release. (In Nautilus, BlueStore tracks its internal usage statistics on a granular, per-pool basis.)

If all OSDs are older than Nautilus, this means that the per-pool metrics are simply unavailable. But if there is a mixture of pre-Nautilus and post-Nautilus OSDs, the cluster usage statistics reported by ceph df will be inaccurate.

The old OSDs can be updated to use the new usage-tracking scheme by stopping each OSD, running a repair operation, and then restarting the OSD. For example, to update osd.123, run the following commands:

systemctl stop ceph-osd@123
ceph-bluestore-tool repair --path /var/lib/ceph/osd/ceph-123
systemctl start ceph-osd@123

To disable this alert, run the following command:

ceph config set global bluestore_warn_on_legacy_statfs false

BLUESTORE_NO_PER_POOL_OMAP¶

One or more OSDs have volumes that were created prior to the Octopus release. (In Octopus and later releases, BlueStore tracks omap space utilization by pool.)

If there are any BlueStore OSDs that do not have the new tracking enabled, the cluster will report an approximate value for per-pool omap usage based on the most recent deep scrub.

The OSDs can be updated to track by pool by stopping each OSD, running a repair operation, and then restarting the OSD. For example, to update osd.123, run the following commands:

systemctl stop ceph-osd@123
ceph-bluestore-tool repair --path /var/lib/ceph/osd/ceph-123
systemctl start ceph-osd@123

To disable this alert, run the following command:

ceph config set global bluestore_warn_on_no_per_pool_omap false

BLUESTORE_NO_PER_PG_OMAP¶

One or more OSDs have volumes that were created prior to Pacific. (In Pacific and later releases Bluestore tracks omap space utilitzation by Placement Group (PG).)

Per-PG omap allows faster PG removal when PGs migrate.

The older OSDs can be updated to track by PG by stopping each OSD, running a repair operation, and then restarting the OSD. For example, to update osd.123, run the following commands:

systemctl stop ceph-osd@123
ceph-bluestore-tool repair --path /var/lib/ceph/osd/ceph-123
systemctl start ceph-osd@123

To disable this alert, run the following command:

ceph config set global bluestore_warn_on_no_per_pg_omap false

BLUESTORE_DISK_SIZE_MISMATCH¶

One or more BlueStore OSDs have an internal inconsistency between the size of the physical device and the metadata that tracks its size. This inconsistency can lead to the OSD(s) crashing in the future.

The OSDs that have this inconsistency should be destroyed and reprovisioned. Be very careful to execute this procedure on only one OSD at a time, so as to minimize the risk of losing any data. To execute this procedure, where $N is the OSD that has the inconsistency, run the following commands:

ceph osd out osd.$N
while ! ceph osd safe-to-destroy osd.$N ; do sleep 1m ; done
ceph osd destroy osd.$N
ceph-volume lvm zap /path/to/device
ceph-volume lvm create --osd-id $N --data /path/to/device

Note

Wait for this recovery procedure to completely on one OSD before running it on the next.

BLUESTORE_NO_COMPRESSION¶

One or more OSDs is unable to load a BlueStore compression plugin. This issue might be caused by a broken installation, in which the ceph-osd binary does not match the compression plugins. Or it might be caused by a recent upgrade in which the ceph-osd daemon was not restarted.

To resolve this issue, verify that all of the packages on the host that is running the affected OSD(s) are correctly installed and that the OSD daemon(s) have been restarted. If the problem persists, check the OSD log for information about the source of the problem.

BLUESTORE_SPURIOUS_READ_ERRORS¶

One or more BlueStore OSDs detect spurious read errors on the main device. BlueStore has recovered from these errors by retrying disk reads. This alert might indicate issues with underlying hardware, issues with the I/O subsystem, or something similar. In theory, such issues can cause permanent data corruption. Some observations on the root cause of spurious read errors can be found here: https://tracker.ceph.com/issues/22464

This alert does not require an immediate response, but the affected host might need additional attention: for example, upgrading the host to the latest OS/kernel versions and implementing hardware-resource-utilization monitoring.

To disable this alert on all OSDs, run the following command:

ceph config set osd bluestore_warn_on_spurious_read_errors false

Or, to disable this alert on a specific OSD, run the following command:

ceph config set osd.123 bluestore_warn_on_spurious_read_errors false

Device health¶

DEVICE_HEALTH¶

One or more OSD devices are expected to fail soon, where the warning threshold is determined by the mgr/devicehealth/warn_threshold config option.

Because this alert applies only to OSDs that are currently marked in, the appropriate response to this expected failure is (1) to mark the OSD out so that data is migrated off of the OSD, and then (2) to remove the hardware from the system. Note that this marking out is normally done automatically if mgr/devicehealth/self_heal is enabled (as determined by mgr/devicehealth/mark_out_threshold).

To check device health, run the following command:

ceph device info <device-id>

Device life expectancy is set either by a prediction model that the mgr runs or by an external tool that is activated by running the following command:

ceph device set-life-expectancy <device-id> <from> <to>

You can change the stored life expectancy manually, but such a change usually doesn’t accomplish anything. The reason for this is that whichever tool originally set the stored life expectancy will probably undo your change by setting it again, and a change to the stored value does not affect the actual health of the hardware device.

DEVICE_HEALTH_IN_USE¶

One or more devices (that is, OSDs) are expected to fail soon and have been marked out of the cluster (as controlled by mgr/devicehealth/mark_out_threshold), but they are still participating in one or more Placement Groups. This might be because the OSD(s) were marked out only recently and data is still migrating, or because data cannot be migrated off of the OSD(s) for some reason (for example, the cluster is nearly full, or the CRUSH hierarchy is structured so that there isn’t another suitable OSD to migrate the data to).

This message can be silenced by disabling self-heal behavior (that is, setting mgr/devicehealth/self_heal to false), by adjusting mgr/devicehealth/mark_out_threshold, or by addressing whichever condition is preventing data from being migrated off of the ailing OSD(s).

DEVICE_HEALTH_TOOMANY¶

Too many devices (that is, OSDs) are expected to fail soon, and because mgr/devicehealth/self_heal behavior is enabled, marking out all of the ailing OSDs would exceed the cluster’s mon_osd_min_in_ratio ratio. This ratio prevents a cascade of too many OSDs from being automatically marked out.

You should promptly add new OSDs to the cluster to prevent data loss, or incrementally replace the failing OSDs.

Alternatively, you can silence this health check by adjusting options including mon_osd_min_in_ratio or mgr/devicehealth/mark_out_threshold. Be warned, however, that this will increase the likelihood of unrecoverable data loss.

Data health (pools & placement groups)¶

PG_AVAILABILITY¶

Data availability is reduced. In other words, the cluster is unable to service potential read or write requests for at least some data in the cluster. More precisely, one or more Placement Groups (PGs) are in a state that does not allow I/O requests to be serviced. Any of the following PG states are problematic if they do not clear quickly: peering, stale, incomplete, and the lack of active.

For detailed information about which PGs are affected, run the following command:

ceph health detail

In most cases, the root cause of this issue is that one or more OSDs are currently down: see OSD_DOWN above.

To see the state of a specific problematic PG, run the following command:

ceph tell <pgid> query

PG_DEGRADED¶

Data redundancy is reduced for some data: in other words, the cluster does not have the desired number of replicas for all data (in the case of replicated pools) or erasure code fragments (in the case of erasure-coded pools). More precisely, one or more Placement Groups (PGs):

have the degraded or undersized flag set, which means that there are not enough instances of that PG in the cluster; or
have not had the clean state set for a long time.

For detailed information about which PGs are affected, run the following command:

ceph health detail

In most cases, the root cause of this issue is that one or more OSDs are currently “down”: see OSD_DOWN above.

To see the state of a specific problematic PG, run the following command:

ceph tell <pgid> query

PG_RECOVERY_FULL¶

Data redundancy might be reduced or even put at risk for some data due to a lack of free space in the cluster. More precisely, one or more Placement Groups have the recovery_toofull flag set, which means that the cluster is unable to migrate or recover data because one or more OSDs are above the full threshold.

For steps to resolve this condition, see OSD_FULL above.

PG_BACKFILL_FULL¶

Data redundancy might be reduced or even put at risk for some data due to a lack of free space in the cluster. More precisely, one or more Placement Groups have the backfill_toofull flag set, which means that the cluster is unable to migrate or recover data because one or more OSDs are above the backfillfull threshold.

For steps to resolve this condition, see OSD_BACKFILLFULL above.

PG_DAMAGED¶

Data scrubbing has discovered problems with data consistency in the cluster. More precisely, one or more Placement Groups either (1) have the inconsistent or snaptrim_error flag set, which indicates that an earlier data scrub operation found a problem, or (2) have the repair flag set, which means that a repair for such an inconsistency is currently in progress.

For more information, see Repairing PG Inconsistencies.

OSD_SCRUB_ERRORS¶

Recent OSD scrubs have discovered inconsistencies. This alert is generally paired with PG_DAMAGED (see above).

For more information, see Repairing PG Inconsistencies.

OSD_TOO_MANY_REPAIRS¶

The count of read repairs has exceeded the config value threshold mon_osd_warn_num_repaired (default: 10). Because scrub handles errors only for data at rest, and because any read error that occurs when another replica is available will be repaired immediately so that the client can get the object data, there might exist failing disks that are not registering any scrub errors. This repair count is maintained as a way of identifying any such failing disks.

LARGE_OMAP_OBJECTS¶

One or more pools contain large omap objects, as determined by osd_deep_scrub_large_omap_object_key_threshold (threshold for the number of keys to determine what is considered a large omap object) or osd_deep_scrub_large_omap_object_value_sum_threshold (the threshold for the summed size in bytes of all key values to determine what is considered a large omap object) or both. To find more information on object name, key count, and size in bytes, search the cluster log for ‘Large omap object found’. This issue can be caused by RGW-bucket index objects that do not have automatic resharding enabled. For more information on resharding, see RGW Dynamic Bucket Index Resharding.

To adjust the thresholds mentioned above, run the following commands:

ceph config set osd osd_deep_scrub_large_omap_object_key_threshold <keys>
ceph config set osd osd_deep_scrub_large_omap_object_value_sum_threshold <bytes>

CACHE_POOL_NEAR_FULL¶

A cache-tier pool is nearly full, as determined by the target_max_bytes and target_max_objects properties of the cache pool. Once the pool reaches the target threshold, write requests to the pool might block while data is flushed and evicted from the cache. This state normally leads to very high latencies and poor performance.

To adjust the cache pool’s target size, run the following commands:

ceph osd pool set <cache-pool-name> target_max_bytes <bytes>
ceph osd pool set <cache-pool-name> target_max_objects <objects>

There might be other reasons that normal cache flush and evict activity are throttled: for example, reduced availability of the base tier, reduced performance of the base tier, or overall cluster load.

TOO_FEW_PGS¶

The number of Placement Groups (PGs) that are in use in the cluster is below the configurable threshold of mon_pg_warn_min_per_osd PGs per OSD. This can lead to suboptimal distribution and suboptimal balance of data across the OSDs in the cluster, and a reduction of overall performance.

If data pools have not yet been created, this condition is expected.

To address this issue, you can increase the PG count for existing pools or create new pools. For more information, see Choosing the number of Placement Groups.

POOL_PG_NUM_NOT_POWER_OF_TWO¶

One or more pools have a pg_num value that is not a power of two. Although this is not strictly incorrect, it does lead to a less balanced distribution of data because some Placement Groups will have roughly twice as much data as others have.

This is easily corrected by setting the pg_num value for the affected pool(s) to a nearby power of two. To do so, run the following command:

ceph osd pool set <pool-name> pg_num <value>

To disable this health check, run the following command:

ceph config set global mon_warn_on_pool_pg_num_not_power_of_two false

POOL_TOO_FEW_PGS¶

One or more pools should probably have more Placement Groups (PGs), given the amount of data that is currently stored in the pool. This issue can lead to suboptimal distribution and suboptimal balance of data across the OSDs in the cluster, and a reduction of overall performance. This alert is raised only if the pg_autoscale_mode property on the pool is set to warn.

To disable the alert, entirely disable auto-scaling of PGs for the pool by running the following command:

ceph osd pool set <pool-name> pg_autoscale_mode off

To allow the cluster to automatically adjust the number of PGs for the pool, run the following command:

ceph osd pool set <pool-name> pg_autoscale_mode on

Alternatively, to manually set the number of PGs for the pool to the recommended amount, run the following command:

ceph osd pool set <pool-name> pg_num <new-pg-num>

For more information, see Choosing the number of Placement Groups and Autoscaling placement groups.

TOO_MANY_PGS¶

The number of Placement Groups (PGs) in use in the cluster is above the configurable threshold of mon_max_pg_per_osd PGs per OSD. If this threshold is exceeded, the cluster will not allow new pools to be created, pool pg_num to be increased, or pool replication to be increased (any of which, if allowed, would lead to more PGs in the cluster). A large number of PGs can lead to higher memory utilization for OSD daemons, slower peering after cluster state changes (for example, OSD restarts, additions, or removals), and higher load on the Manager and Monitor daemons.

The simplest way to mitigate the problem is to increase the number of OSDs in the cluster by adding more hardware. Note that, because the OSD count that is used for the purposes of this health check is the number of in OSDs, marking out OSDs in (if there are any out OSDs available) can also help. To do so, run the following command:

ceph osd in <osd id(s)>

For more information, see Choosing the number of Placement Groups.

POOL_TOO_MANY_PGS¶

One or more pools should probably have fewer Placement Groups (PGs), given the amount of data that is currently stored in the pool. This issue can lead to higher memory utilization for OSD daemons, slower peering after cluster state changes (for example, OSD restarts, additions, or removals), and higher load on the Manager and Monitor daemons. This alert is raised only if the pg_autoscale_mode property on the pool is set to warn.

To disable the alert, entirely disable auto-scaling of PGs for the pool by running the following command:

ceph osd pool set <pool-name> pg_autoscale_mode off

To allow the cluster to automatically adjust the number of PGs for the pool, run the following command:

ceph osd pool set <pool-name> pg_autoscale_mode on

Alternatively, to manually set the number of PGs for the pool to the recommended amount, run the following command:

ceph osd pool set <pool-name> pg_num <new-pg-num>

For more information, see Choosing the number of Placement Groups and Autoscaling placement groups.

POOL_TARGET_SIZE_BYTES_OVERCOMMITTED¶

One or more pools have a target_size_bytes property that is set in order to estimate the expected size of the pool, but the value(s) of this property are greater than the total available storage (either by themselves or in combination with other pools).

This alert is usually an indication that the target_size_bytes value for the pool is too large and should be reduced or set to zero. To reduce the target_size_bytes value or set it to zero, run the following command:

ceph osd pool set <pool-name> target_size_bytes 0

The above command sets the value of target_size_bytes to zero. To set the value of target_size_bytes to a non-zero value, replace the 0 with that non-zero value.

For more information, see Specifying expected pool size.

POOL_HAS_TARGET_SIZE_BYTES_AND_RATIO¶

One or more pools have both target_size_bytes and target_size_ratio set in order to estimate the expected size of the pool. Only one of these properties should be non-zero. If both are set to a non-zero value, then target_size_ratio takes precedence and target_size_bytes is ignored.

To reset target_size_bytes to zero, run the following command:

ceph osd pool set <pool-name> target_size_bytes 0

For more information, see Specifying expected pool size.

TOO_FEW_OSDS¶

The number of OSDs in the cluster is below the configurable threshold of osd_pool_default_size. This means that some or all data may not be able to satisfy the data protection policy specified in CRUSH rules and pool settings.

SMALLER_PGP_NUM¶

One or more pools have a pgp_num value less than pg_num. This alert is normally an indication that the Placement Group (PG) count was increased without any increase in the placement behavior.

This disparity is sometimes brought about deliberately, in order to separate out the split step when the PG count is adjusted from the data migration that is needed when pgp_num is changed.

This issue is normally resolved by setting pgp_num to match pg_num, so as to trigger the data migration, by running the following command:

ceph osd pool set <pool> pgp_num <pg-num-value>

MANY_OBJECTS_PER_PG¶

One or more pools have an average number of objects per Placement Group (PG) that is significantly higher than the overall cluster average. The specific threshold is determined by the mon_pg_warn_max_object_skew configuration value.

This alert is usually an indication that the pool(s) that contain most of the data in the cluster have too few PGs, or that other pools that contain less data have too many PGs. See TOO_MANY_PGS above.

To silence the health check, raise the threshold by adjusting the mon_pg_warn_max_object_skew config option on the managers.

The health check will be silenced for a specific pool only if pg_autoscale_mode is set to on.

POOL_APP_NOT_ENABLED¶

A pool exists that contains one or more objects, but the pool has not been tagged for use by a particular application.

To resolve this issue, tag the pool for use by an application. For example, if the pool is used by RBD, run the following command:

rbd pool init <poolname>

Alternatively, if the pool is being used by a custom application (here ‘foo’), you can label the pool by running the following low-level command:

ceph osd pool application enable foo

For more information, see Associate Pool to Application.

POOL_FULL¶

One or more pools have reached (or are very close to reaching) their quota. The threshold to raise this health check is determined by the mon_pool_quota_crit_threshold configuration option.

Pool quotas can be adjusted up or down (or removed) by running the following commands:

ceph osd pool set-quota <pool> max_bytes <bytes>
ceph osd pool set-quota <pool> max_objects <objects>

To disable a quota, set the quota value to 0.

POOL_NEAR_FULL¶

One or more pools are approaching a configured fullness threshold.

One of the several thresholds that can raise this health check is determined by the mon_pool_quota_warn_threshold configuration option.

Pool quotas can be adjusted up or down (or removed) by running the following commands:

ceph osd pool set-quota <pool> max_bytes <bytes>
ceph osd pool set-quota <pool> max_objects <objects>

To disable a quota, set the quota value to 0.

Other thresholds that can raise the two health checks above are mon_osd_nearfull_ratio and mon_osd_full_ratio. For details and resolution, see Storage Capacity and No Free Drive Space.

OBJECT_MISPLACED¶

One or more objects in the cluster are not stored on the node that CRUSH would prefer that they be stored on. This alert is an indication that data migration due to a recent cluster change has not yet completed.

Misplaced data is not a dangerous condition in and of itself; data consistency is never at risk, and old copies of objects will not be removed until the desired number of new copies (in the desired locations) has been created.

OBJECT_UNFOUND¶

One or more objects in the cluster cannot be found. More precisely, the OSDs know that a new or updated copy of an object should exist, but no such copy has been found on OSDs that are currently online.

Read or write requests to unfound objects will block.

Ideally, a “down” OSD that has a more recent copy of the unfound object can be brought back online. To identify candidate OSDs, check the peering state of the PG(s) responsible for the unfound object. To see the peering state, run the following command:

ceph tell <pgid> query

On the other hand, if the latest copy of the object is not available, the cluster can be told to roll back to a previous version of the object. For more information, see Unfound Objects.

SLOW_OPS¶

One or more OSD requests or monitor requests are taking a long time to process. This alert might be an indication of extreme load, a slow storage device, or a software bug.

To query the request queue for the daemon that is causing the slowdown, run the following command from the daemon’s host:

ceph daemon osd.<id> ops

To see a summary of the slowest recent requests, run the following command:

ceph daemon osd.<id> dump_historic_ops

To see the location of a specific OSD, run the following command:

ceph osd find osd.<id>

PG_NOT_SCRUBBED¶

One or more PGs has not been scrubbed recently. PGs are normally scrubbed within every configured interval specified by osd_scrub_max_interval globally. This interval can be overriden on per-pool basis with scrub_max_interval. The warning triggers when mon_warn_pg_not_scrubbed_ratio percentage of interval has elapsed without a scrub since it was due.

PGs will be scrubbed only if they are flagged as clean (which means that they are to be cleaned, and not that they have been examined and found to be clean). Misplaced or degraded PGs will not be flagged as clean (see PG_AVAILABILITY and PG_DEGRADED above).

To manually initiate a scrub of a clean PG, run the following command:

PG_NOT_DEEP_SCRUBBED¶

One or more PGs has not been deep scrubbed recently. PGs are normally scrubbed every osd_deep_scrub_interval seconds, and this warning triggers when mon_warn_pg_not_deep_scrubbed_ratio percentage of interval has elapsed without a scrub since it was due.

PGs will receive a deep scrub only if they are flagged as clean (which means that they are to be cleaned, and not that they have been examined and found to be clean). Misplaced or degraded PGs might not be flagged as clean (see PG_AVAILABILITY and PG_DEGRADED above).

To manually initiate a deep scrub of a clean PG, run the following command:

ceph pg deep-scrub <pgid>

PG_SLOW_SNAP_TRIMMING¶

The snapshot trim queue for one or more PGs has exceeded the configured warning threshold. This alert indicates either that an extremely large number of snapshots was recently deleted, or that OSDs are unable to trim snapshots quickly enough to keep up with the rate of new snapshot deletions.

The warning threshold is determined by the mon_osd_snap_trim_queue_warn_on option (default: 32768).

This alert might be raised if OSDs are under excessive load and unable to keep up with their background work, or if the OSDs’ internal metadata database is heavily fragmented and unable to perform. The alert might also indicate some other performance issue with the OSDs.

The exact size of the snapshot trim queue is reported by the snaptrimq_len field of ceph pg ls -f json-detail.

Miscellaneous¶

RECENT_CRASH¶

One or more Ceph daemons have crashed recently, and the crash(es) have not yet been acknowledged and archived by the administrator. This alert might indicate a software bug, a hardware problem (for example, a failing disk), or some other problem.

To list recent crashes, run the following command:

ceph crash ls-new

To examine information about a specific crash, run the following command:

ceph crash info <crash-id>

To silence this alert, you can archive the crash (perhaps after the crash has been examined by an administrator) by running the following command:

ceph crash archive <crash-id>

Similarly, to archive all recent crashes, run the following command:

ceph crash archive-all

Archived crashes will still be visible by running the command ceph crash ls, but not by running the command ceph crash ls-new.

The time period that is considered recent is determined by the option mgr/crash/warn_recent_interval (default: two weeks).

To entirely disable this alert, run the following command:

ceph config set mgr/crash/warn_recent_interval 0

RECENT_MGR_MODULE_CRASH¶

One or more ceph-mgr modules have crashed recently, and the crash(es) have not yet been acknowledged and archived by the administrator. This alert usually indicates a software bug in one of the software modules that are running inside the ceph-mgr daemon. The module that experienced the problem might be disabled as a result, but other modules are unaffected and continue to function as expected.

As with the RECENT_CRASH health check, a specific crash can be inspected by running the following command:

ceph crash info <crash-id>

To silence this alert, you can archive the crash (perhaps after the crash has been examined by an administrator) by running the following command:

ceph crash archive <crash-id>

Similarly, to archive all recent crashes, run the following command:

ceph crash archive-all

Archived crashes will still be visible by running the command ceph crash ls but not by running the command ceph crash ls-new.

The time period that is considered recent is determined by the option mgr/crash/warn_recent_interval (default: two weeks).

To entirely disable this alert, run the following command:

ceph config set mgr/crash/warn_recent_interval 0

TELEMETRY_CHANGED¶

Telemetry has been enabled, but because the contents of the telemetry report have changed in the meantime, telemetry reports will not be sent.

Ceph developers occasionally revise the telemetry feature to include new and useful information, or to remove information found to be useless or sensitive. If any new information is included in the report, Ceph requires the administrator to re-enable telemetry. This requirement ensures that the administrator has an opportunity to (re)review the information that will be shared.

To review the contents of the telemetry report, run the following command:

ceph telemetry show

Note that the telemetry report consists of several channels that may be independently enabled or disabled. For more information, see Telemetry Module.

To re-enable telemetry (and silence the alert), run the following command:

ceph telemetry on

To disable telemetry (and silence the alert), run the following command:

ceph telemetry off

AUTH_BAD_CAPS¶

One or more auth users have capabilities that cannot be parsed by the monitors. As a general rule, this alert indicates that there are one or more daemon types that the user is not authorized to use to perform any action.

This alert is most likely to be raised after an upgrade if (1) the capabilities were set with an older version of Ceph that did not properly validate the syntax of those capabilities, or if (2) the syntax of the capabilities has changed.

To remove the user(s) in question, run the following command:

ceph auth rm <entity-name>

(This resolves the health check, but it prevents clients from being able to authenticate as the removed user.)

Alternatively, to update the capabilities for the user(s), run the following command:

ceph auth <entity-name> <daemon-type> <caps> [<daemon-type> <caps> ...]

For more information about auth capabilities, see User Management.

OSD_NO_DOWN_OUT_INTERVAL¶

The mon_osd_down_out_interval option is set to zero, which means that the system does not automatically perform any repair or healing operations when an OSD fails. Instead, an administrator an external orchestrator must manually mark “down” OSDs as out (by running ceph osd out <osd-id>) in order to trigger recovery.

This option is normally set to five or ten minutes, which should be enough time for a host to power-cycle or reboot.

To silence this alert, set mon_warn_on_osd_down_out_interval_zero to false by running the following command:

ceph config global mon mon_warn_on_osd_down_out_interval_zero false

DASHBOARD_DEBUG¶

The Dashboard debug mode is enabled. This means that if there is an error while processing a REST API request, the HTTP error response will contain a Python traceback. This mode should be disabled in production environments because such a traceback might contain and expose sensitive information.

To disable the debug mode, run the following command:

ceph dashboard debug disable