Ceph OSD daemon crash

Software bugs or hardware issues

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 known for its reliability, scalability, and performance, making it a popular choice for cloud infrastructure and large-scale data storage solutions. Ceph's architecture is based on the Reliable Autonomic Distributed Object Store (RADOS), which allows it to manage data across a distributed cluster of storage nodes.

Recognizing the Symptom: OSD Daemon Crash

One of the common issues encountered in a Ceph cluster is the crash of an Object Storage Daemon (OSD). When an OSD daemon crashes, it can lead to degraded performance, data unavailability, or even data loss if not addressed promptly. The symptom of this issue is typically observed as an OSD being marked as 'down' or 'out' in the Ceph cluster status.

Identifying the Error

To identify an OSD crash, you can use the following command to check the status of your Ceph cluster:

ceph -s

This command will provide an overview of the cluster's health, including any OSDs that are down or out. Additionally, you may see error messages in the Ceph logs indicating a crash.

Details About the OSD Crash Issue

An OSD crash can occur due to various reasons, including software bugs, hardware failures, or configuration issues. When an OSD crashes, it stops responding to requests, which can disrupt the normal operation of the Ceph cluster. The root cause of the crash can often be found in the OSD logs, which provide detailed information about the events leading up to the crash.

Common Causes of OSD Crashes

Software bugs in the Ceph codebase.
Hardware failures such as disk errors or network issues.
Configuration errors or resource limitations.

Steps to Fix the OSD Crash Issue

To resolve an OSD crash, follow these steps:

Step 1: Check OSD Logs

Examine the OSD logs to identify the cause of the crash. The logs are typically located in /var/log/ceph/. Use the following command to view the logs:

less /var/log/ceph/ceph-osd.<osd-number>.log

Look for any error messages or stack traces that can provide clues about the crash.

Step 2: Apply Available Patches

If the crash is due to a known bug, check the Ceph release notes for any patches or updates that address the issue. Apply the necessary updates to your Ceph cluster.

Step 3: Restart the OSD Daemon

After addressing the root cause, restart the OSD daemon to bring it back online. Use the following command to restart the OSD:

systemctl restart ceph-osd@<osd-number>

Verify that the OSD is back online by checking the cluster status:

ceph -s

Conclusion

By following these steps, you can diagnose and resolve OSD crashes in your Ceph cluster. Regular monitoring and maintenance of your Ceph environment can help prevent such issues from occurring in the future. For more detailed information on managing Ceph, 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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