Ceph PG_INCOMPLETE

PGs are incomplete, often due to missing OSDs or data corruption.

Understanding Ceph and Its Purpose

Ceph is an open-source storage platform designed to provide highly scalable object, block, and file-based storage under a unified system. It is widely used for its ability to handle large amounts of data with high availability and redundancy. Ceph achieves this through its distributed architecture, which allows for data replication and fault tolerance across multiple nodes.

Identifying the Symptom: PG_INCOMPLETE

One of the common issues encountered in Ceph is the PG_INCOMPLETE state. This symptom is observed when Placement Groups (PGs) are incomplete, which can lead to data inaccessibility and potential data loss if not addressed promptly. The ceph status command may show PGs in an incomplete state, indicating a problem that needs immediate attention.

Explaining the PG_INCOMPLETE Issue

The PG_INCOMPLETE state occurs when PGs are unable to reach a complete state due to missing Object Storage Daemons (OSDs) or data corruption. This can happen if OSDs are down, out, or if there is a network partition affecting the cluster's ability to maintain data consistency and redundancy. Incomplete PGs mean that the data is not fully replicated, which poses a risk to data integrity.

Root Causes of PG_INCOMPLETE

Missing or down OSDs.
Data corruption within the PGs.
Network issues causing partitioning or latency.

Steps to Resolve PG_INCOMPLETE

Resolving the PG_INCOMPLETE issue involves identifying and addressing the underlying causes. Here are the steps to follow:

Step 1: Check Cluster Health

Start by checking the overall health of the Ceph cluster using the following command:

ceph status

This command provides an overview of the cluster's state, including any warnings or errors related to PGs.

Step 2: Identify Missing OSDs

Use the following command to list all OSDs and their status:

ceph osd tree

Look for any OSDs that are marked as down or out. Investigate why these OSDs are not operational and attempt to bring them back online.

Step 3: Investigate Data Corruption

If OSDs are operational but PGs remain incomplete, data corruption might be the cause. Check the logs for any errors related to data corruption:

ceph pg dump | grep incomplete

Review the logs for any signs of corruption and consider using tools like Ceph's troubleshooting guide to address these issues.

Step 4: Allow Time for Recovery

Once the underlying issues are addressed, allow the cluster some time to recover and complete the PGs. Monitor the cluster's status periodically to ensure that the PGs transition from PG_INCOMPLETE to a healthy state.

Conclusion

Addressing the PG_INCOMPLETE issue in Ceph requires a systematic approach to diagnose and resolve the underlying causes. By ensuring all OSDs are operational and addressing any data corruption, you can restore the cluster to a healthy state. For more detailed guidance, refer to the official Ceph documentation.

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MORE ISSUES

PGs are undergoing repair operations, often due to data inconsistencies or corruption.

Ceph Monitor disk I/O error affecting Ceph monitor functionality.

A monitor's disk is experiencing I/O errors.

Ceph OSD_DISK_IO_ERROR

An OSD's disk is experiencing I/O errors, affecting its ability to store data.

Ceph MDS_DISK_FULL

The MDS's disk is full, affecting its ability to function properly.

Ceph RADOS Gateway experiencing performance issues due to network problems.

Network configurations or connectivity issues affecting RADOS Gateway communication.

Ceph The RADOS Gateway service is down, affecting object storage access.

The RADOS Gateway service is not running, which could be due to network issues, resource constraints, or configuration errors.

Ceph Network congestion is affecting OSD communication, leading to performance degradation.

Network congestion is affecting OSD communication, leading to performance degradation.

Ceph PG_BACKFILL

PGs are undergoing backfill operations, often due to OSD additions or recoveries.

Ceph POOL_QUOTA_EXCEEDED

A pool has exceeded its configured quota, preventing further writes.

Ceph Monitor experiencing high CPU usage

A monitor is experiencing high CPU usage, affecting its performance.

Ceph OSD_DISK_SLOW

An OSD's disk is performing slowly, affecting its ability to serve data.

Ceph MDS_NETWORK_ISSUE

Network issues are affecting MDS communication, leading to performance problems.

Ceph OSD is experiencing high CPU usage.

An OSD is experiencing high CPU usage, affecting its performance.

Ceph Authentication failures when accessing the RADOS Gateway.

Incorrect credentials or configuration settings.

Ceph PG_SCRUB_ERRORS

Errors occurred during PG scrubbing, possibly due to data corruption.

Ceph A monitor is consuming excessive memory, possibly due to a memory leak.

A monitor is consuming excessive memory, possibly due to a memory leak.

Ceph High network latency is affecting OSD performance.

High network latency

Ceph RGW_BUCKET_NOT_FOUND

A requested bucket does not exist in the RADOS Gateway.

Ceph The MDS is consuming excessive memory, possibly due to a memory leak.

The MDS is consuming excessive memory, possibly due to a memory leak.

Ceph An OSD is consuming excessive memory, possibly due to a memory leak.

The OSD process may have a memory leak, causing it to consume more memory than expected.

Ceph OSD_DISK_FAILURE

An OSD's disk has failed, affecting its ability to store data.

Ceph PG_INCOMPLETE

PGs are incomplete, often due to missing OSDs or data corruption.

Ceph Monitor nodes are experiencing communication issues, leading to quorum problems.

Network issues are affecting monitor communication.

An MDS instance is stale, possibly due to network issues or failover problems.

Ceph Monitor daemon crash in Ceph cluster.

A monitor daemon has crashed, possibly due to software bugs or resource exhaustion.

Ceph An OSD's journal is full, affecting its ability to process writes.

The journal size is insufficient for the current workload, or there may be a configuration issue.

Ceph POOL_NOT_FOUND

A requested pool does not exist, possibly due to configuration errors or deletion.

Ceph OSD_NETWORK_ISSUE

Network issues are affecting OSD communication, leading to degraded performance or failures.

Ceph An OSD is repeatedly going up and down, often due to unstable hardware or network issues.

Unstable hardware or network issues causing OSD flapping.

The RADOS Gateway is experiencing slow performance, possibly due to high load or resource constraints.

Ceph The MDS is overloaded, affecting CephFS performance.

The MDS is overloaded due to high metadata operations, insufficient resources, or improper configuration.

Ceph OSD daemon crash

Software bugs or hardware issues

Ceph PG_UNCLEAN

PGs are not in a clean state, often due to OSD failures or ongoing recovery operations.

Ceph Monitor disk is full, causing operational issues.

The monitor's disk has reached its storage capacity limit.

Ceph INCOMPATIBLE_CLIENT error encountered when a client tries to connect to the Ceph cluster.

A client is using an incompatible version of the Ceph software.

Ceph SLOW_REQUESTS

Requests to the cluster are slow, possibly due to high load or resource contention.

Ceph RADOSGW_UNAVAILABLE

The RADOS Gateway (RGW) is unavailable, affecting object storage access.

Ceph MDS failover is not occurring as expected.

Configuration issues with MDS or improperly configured standby MDS instances.

The Metadata Server (MDS) is down, affecting CephFS operations.

Ceph Communication issues between Ceph components due to network partition.

A network partition is causing communication issues between Ceph components.

Ceph CRUSH_MAP_ERROR

Errors in the CRUSH map configuration, potentially causing data placement issues.

Ceph Authentication failure between Ceph components.

Incorrect keyring or configuration settings.

Ceph An OSD has reached its full capacity, preventing further writes.

An OSD has reached its full capacity, preventing further writes.

Operations are taking longer than expected, possibly due to high load, network latency, or hardware bottlenecks.

Ceph MON_QUORUM_LOST

The monitor quorum is lost, often due to network partitions or multiple monitor failures.

PGs are stuck in a non-active state, possibly due to OSDs being down or network partitions.

Ceph PG_DEGRADED

Placement Groups (PGs) are not fully replicated, often due to OSD failures or network issues.

Ceph An OSD is marked as out, meaning it is not part of the active cluster and not serving data.

The OSD might be down or manually marked out due to maintenance or failure.

Ceph An OSD is marked as down in the Ceph cluster.

Network issues, hardware failure, or the OSD daemon crashing.

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