Health checks¶
Overview¶
There is a finite set of possible health messages that a Ceph cluster can raise – these are defined as health checks which have unique identifiers.
The identifier is a terse pseudo-human-readable (i.e. like a variable name) string. It is intended to enable tools (such as 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 may also see health checks that originate from MDS daemons (see CephFS health messages), and health checks that are defined by ceph-mgr python modules.
Definitions¶
Manager¶
MGR_MODULE_DEPENDENCY¶
An enabled manager module is failing its dependency check. This health check should come with an explanatory message from the module about the problem.
For example, a module might report that a required package is not installed: install the required package and restart your manager daemons.
This health check is only applied 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 an unhandled exception was raised from the module’s serve function. The human readable description of the error may be obscurely worded if the exception did not provide a useful description of itself.
This health check may indicate a bug: please open a Ceph bug report if you think you have encountered a bug.
If you believe the error is transient, you may restart your manager daemon(s), or use ceph mgr fail on the active daemon to prompt a failover to another daemon.
OSDs¶
OSD_DOWN¶
One or more OSDs are marked down. The ceph-osd daemon may have been stopped, or peer OSDs may 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 the host is healthy, the daemon is started, and network is
functioning. If the daemon has crashed, the daemon log file
(/var/log/ceph/ceph-osd.*) may contain debugging information.
OSD_<crush type>_DOWN¶
(e.g. OSD_HOST_DOWN, OSD_ROOT_DOWN)
All 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.
The OSD can be removed from the CRUSH hierarchy with:
ceph osd crush rm osd.<id>
OSD_OUT_OF_ORDER_FULL¶
The utilization thresholds for backfillfull, nearfull, full, and/or failsafe_full are not ascending. In particular, we expect backfillfull < nearfull, nearfull < full, and full < failsafe_full.
The thresholds can be adjusted with:
ceph osd set-backfillfull-ratio <ratio>
ceph osd set-nearfull-ratio <ratio>
ceph osd set-full-ratio <ratio>
OSD_FULL¶
One or more OSDs has exceeded the full threshold and is preventing the cluster from servicing writes.
Utilization by pool can be checked with:
ceph df
The currently defined full ratio can be seen with:
ceph osd dump | grep full_ratio
A short-term workaround to restore write availability is to raise the full threshold by a small amount:
ceph osd set-full-ratio <ratio>
New storage should be added to the cluster by deploying more OSDs or existing data should be deleted in order to free up space.
OSD_BACKFILLFULL¶
One or more OSDs has exceeded the backfillfull threshold, which will prevent data from being allowed to rebalance to this device. This is an early warning that rebalancing may not be able to complete and that the cluster is approaching full.
Utilization by pool can be checked with:
ceph df
OSD_NEARFULL¶
One or more OSDs has exceeded the nearfull threshold. This is an early warning that the cluster is approaching full.
Utilization by pool can be checked with:
ceph df
OSDMAP_FLAGS¶
One or more cluster flags of interest has been set. These flags include:
full - the cluster is flagged as full and cannot service writes
pauserd, pausewr - paused reads or writes
noup - OSDs are not allowed to start
nodown - OSD failure reports are being ignored, such that the monitors will not mark OSDs down
noin - OSDs that were previously marked out will not be marked back in when they start
noout - down OSDs will not automatically be 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 with:
ceph osd set <flag>
ceph osd unset <flag>
OSD_FLAGS¶
One or more OSDs has a per-OSD flag of interest set. These flags include:
noup: OSD is not allowed to start
nodown: failure reports for this OSD will be ignored
noin: if this OSD was previously marked out automatically after a failure, it will not be marked in when it stats
noout: if this OSD is down it will not automatically be marked out after the configured interval
Per-OSD flags can be set and cleared with:
ceph osd add-<flag> <osd-id>
ceph osd rm-<flag> <osd-id>
For example,
ceph osd rm-nodown osd.123
OLD_CRUSH_TUNABLES¶
The CRUSH map is using very old settings and should be updated. The
oldest tunables that can be used (i.e., the oldest client version that
can connect to the cluster) without triggering this health warning is
determined by the mon_crush_min_required_version config option.
See Tunables for more information.
OLD_CRUSH_STRAW_CALC_VERSION¶
The CRUSH map is using an older, non-optimal method for calculating
intermediate weight values for straw buckets.
The CRUSH map should be updated to use the newer method
(straw_calc_version=1). See
Tunables for more information.
CACHE_POOL_NO_HIT_SET¶
One or more cache pools is not configured with a hit set to track utilization, which will prevent the tiering agent from identifying cold objects to flush and evict from the cache.
Hit sets can be configured on the cache pool with:
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 before luminous v12.y.z or newer
OSDs can start. You can safely set the flag with:
ceph osd set sortbitwise
POOL_FULL¶
One or more pools has reached its quota and is no longer allowing writes.
Pool quotas and utilization can be seen with:
ceph df detail
You can either raise the pool quota with:
ceph osd pool set-quota <poolname> max_objects <num-objects>
ceph osd pool set-quota <poolname> max_bytes <num-bytes>
or delete some existing data to reduce utilization.
Data health (pools & placement groups)¶
PG_AVAILABILITY¶
Data availability is reduced, meaning that the cluster is unable to service potential read or write requests for some data in the cluster. Specifically, one or more PGs is in a state that does not allow IO requests to be serviced. Problematic PG states include peering, stale, incomplete, and the lack of active (if those conditions do not clear quickly).
Detailed information about which PGs are affected is available from:
ceph health detail
In most cases the root cause is that one or more OSDs is currently
down; see the dicussion for OSD_DOWN above.
The state of specific problematic PGs can be queried with:
ceph tell <pgid> query
PG_DEGRADED¶
Data redundancy is reduced for some data, meaning the cluster does not have the desired number of replicas for all data (for replicated pools) or erasure code fragments (for erasure coded pools). Specifically, one or more PGs:
has the degraded or undersized flag set, meaning there are not enough instances of that placement group in the cluster;
has not had the clean flag set for some time.
Detailed information about which PGs are affected is available from:
ceph health detail
In most cases the root cause is that one or more OSDs is currently
down; see the dicussion for OSD_DOWN above.
The state of specific problematic PGs can be queried with:
ceph tell <pgid> query
PG_DEGRADED_FULL¶
Data redundancy may be reduced or at risk for some data due to a lack of free space in the cluster. Specifically, one or more PGs has the backfill_toofull or recovery_toofull flag set, meaning that the cluster is unable to migrate or recover data because one or more OSDs is above the backfillfull threshold.
See the discussion for OSD_BACKFILLFULL or OSD_FULL above for steps to resolve this condition.
PG_DAMAGED¶
Data scrubbing has discovered some problems with data consistency in the cluster. Specifically, one or more PGs has the inconsistent or snaptrim_error flag is set, indicating an earlier scrub operation found a problem, or that the repair flag is set, meaning a repair for such an inconsistency is currently in progress.
See Repairing PG inconsistencies for more information.
OSD_SCRUB_ERRORS¶
Recent OSD scrubs have uncovered inconsistencies. This error is generally paired with PG_DAMANGED (see above).
See Repairing PG inconsistencies for more information.
CACHE_POOL_NEAR_FULL¶
A cache tier pool is nearly full. Full in this context is determined
by the target_max_bytes and target_max_objects properties on
the cache pool. Once the pool reaches the target threshold, write
requests to the pool may block while data is flushed and evicted
from the cache, a state that normally leads to very high latencies and
poor performance.
The cache pool target size can be adjusted with:
ceph osd pool set <cache-pool-name> target_max_bytes <bytes>
ceph osd pool set <cache-pool-name> target_max_objects <objects>
Normal cache flush and evict activity may also be throttled due to reduced availability or performance of the base tier, or overall cluster load.
TOO_FEW_PGS¶
The number of PGs in use in the cluster is below the configurable
threshold of mon_pg_warn_min_per_osd PGs per OSD. This can lead
to suboptimizal distribution and balance of data across the OSDs in
the cluster, and similar reduce overall performance.
This may be an expected condition if data pools have not yet been created.
The PG count for existing pools can be increased or new pools can be created. Please refer to Choosing the number of Placement Groups for more information.
TOO_MANY_PGS¶
The number of PGs in use in the cluster is above the configurable
threshold of mon_max_pg_per_osd PGs per OSD. If this threshold is
exceed 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 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 (like 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 the OSD count used for the purposes of this health check is the number of “in” OSDs, so marking “out” OSDs “in” (if there are any) can also help:
ceph osd in <osd id(s)>
Please refer to Choosing the number of Placement Groups for more information.
TOO_FEW_OSDS¶
The number of OSDs in the cluster is below the configurable
threshold of osd_pool_default_size.
SMALLER_PGP_NUM¶
One or more pools has a pgp_num value less than pg_num. This
is normally an indication that the PG count was increased without
also increasing the placement behavior.
This is sometimes done deliberately 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 is normally resolved by setting pgp_num to match pg_num,
triggering the data migration, with:
ceph osd pool set <pool> pgp_num <pg-num-value>
MANY_OBJECTS_PER_PG¶
One or more pools has an average number of objects per PG that is
significantly higher than the overall cluster average. The specific
threshold is controlled by the mon_pg_warn_max_object_skew
configuration value.
This is usually an indication that the pool(s) containing most of the data in the cluster have too few PGs, and/or that other pools that do not contain as much data have too many PGs. See the discussion of TOO_MANY_PGS above.
The threshold can be raised to silence the health warning by adjusting
the mon_pg_warn_max_object_skew config option on the monitors.
POOL_APP_NOT_ENABLED¶
A pool exists that contains one or more objects but has not been tagged for use by a particular application.
Resolve this warning by labeling the pool for use by an application. For example, if the pool is used by RBD,:
rbd pool init <poolname>
If the pool is being used by a custom application ‘foo’, you can also label via the low-level command:
ceph osd pool application enable foo
For more information, see Associate Pool to Application.
POOL_FULL¶
One or more pools has reached (or is very close to reaching) its
quota. The threshold to trigger this error condition is controlled by
the mon_pool_quota_crit_threshold configuration option.
Pool quotas can be adjusted up or down (or removed) with:
ceph osd pool set-quota <pool> max_bytes <bytes>
ceph osd pool set-quota <pool> max_objects <objects>
Setting the quota value to 0 will disable the quota.
POOL_NEAR_FULL¶
One or more pools is approaching is quota. The threshold to trigger
this warning condition is controlled by the
mon_pool_quota_warn_threshold configuration option.
Pool quotas can be adjusted up or down (or removed) with:
ceph osd pool set-quota <pool> max_bytes <bytes>
ceph osd pool set-quota <pool> max_objects <objects>
Setting the quota value to 0 will disable the quota.
OBJECT_MISPLACED¶
One or more objects in the cluster is not stored on the node the cluster would like it to be stored on. This is an indication that data migration due to some 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 are never removed until the desired number of new copies (in the desired locations) are present.
OBJECT_UNFOUND¶
One or more objects in the cluster cannot be found. Specifically, the OSDs know that a new or updated copy of an object should exist, but a copy of that version of the object has not been found on OSDs that are currently online.
Read or write requests to unfound objects will block.
Ideally, a down OSD can be brought back online that has the more recent copy of the unfound object. Candidate OSDs can be identified from the peering state for the PG(s) responsible for the unfound object:
ceph tell <pgid> query
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. See Unfound Objects for more information.
SLOW_OPS¶
One or more OSD requests is taking a long time to process. This can be an indication of extreme load, a slow storage device, or a software bug.
The request queue on the OSD(s) in question can be queried with the following command, executed from the OSD host:
ceph daemon osd.<id> ops
A summary of the slowest recent requests can be seen with:
ceph daemon osd.<id> dump_historic_ops
The location of an OSD can be found with:
ceph osd find osd.<id>
PG_NOT_SCRUBBED¶
One or more PGs has not been scrubbed recently. PGs are normally
scrubbed every mon_scrub_interval seconds, and this warning
triggers when mon_warn_not_scrubbed such intervals have elapsed
without a scrub.
PGs will not scrub if they are not flagged as clean, which may happen if they are misplaced or degraded (see PG_AVAILABILITY and PG_DEGRADED above).
You can manually initiate a scrub of a clean PG with:
ceph pg scrub <pgid>
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_not_deep_scrubbed such intervals have elapsed
without a scrub.
PGs will not (deep) scrub if they are not flagged as clean, which may happen if they are misplaced or degraded (see PG_AVAILABILITY and PG_DEGRADED above).
You can manually initiate a scrub of a clean PG with:
ceph pg deep-scrub <pgid>
