Ceph is a highly scalable distributed storage system designed to provide excellent performance, reliability, and scalability. It is used to manage large amounts of data across a cluster of commodity hardware. Ceph's architecture is based on the Reliable Autonomic Distributed Object Store (RADOS), which allows for seamless data distribution and redundancy.
Ceph is commonly used in cloud environments and data centers to provide block storage, object storage, and file system storage. Its ability to scale horizontally and handle petabytes of data makes it a popular choice for organizations looking to implement a robust storage solution.
The symptom of the FULL_OSD issue is that one or more Object Storage Daemons (OSDs) in the Ceph cluster have reached their full capacity. This situation prevents further write operations to the affected OSDs, potentially impacting the overall performance and availability of the storage cluster.
When an OSD is full, you may observe warning messages in the Ceph dashboard or logs indicating that the OSD is unable to accommodate additional data. This can lead to degraded performance and may affect the cluster's ability to maintain data redundancy and balance.
The FULL_OSD issue occurs when an OSD in the Ceph cluster reaches its maximum storage capacity. Ceph uses a CRUSH algorithm to distribute data across OSDs, and when an OSD is full, it can no longer accept new data. This can result in write operations being blocked or redirected to other OSDs, potentially leading to an imbalance in data distribution.
The root cause of the FULL_OSD issue is typically a lack of available storage space on the affected OSDs. This can occur due to insufficient capacity planning, unexpected data growth, or inadequate monitoring of storage usage.
To resolve the FULL_OSD issue, you can take the following steps:
Identify and delete unnecessary data from the full OSDs. This can include old snapshots, temporary files, or unused data. Use the following command to check the usage of each OSD:
ceph osd df
This command will display the disk usage of each OSD, helping you identify which OSDs are full.
To increase the cluster's capacity, consider adding more OSDs. This will distribute the data more evenly across the cluster and provide additional storage space. Follow these steps to add a new OSD:
ceph-volume lvm create --data /dev/sdX
ceph osd crush add osd.<id> <weight> host=<hostname>
Regularly monitor the cluster's health and storage usage to prevent future occurrences of the FULL_OSD issue. Use the Ceph dashboard or the following command to check the cluster's status:
ceph status
This command provides an overview of the cluster's health, including any warnings or errors related to storage capacity.
For more information on managing Ceph storage and resolving common issues, refer to the following resources:
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