Thanos compaction: block overlaps detected

What is Thanos compaction: block overlaps detected

Understanding Thanos and Its Purpose

Thanos is an open-source project that provides highly available Prometheus setup with long-term storage capabilities. It is designed to aggregate data from multiple Prometheus instances and store it in a highly available manner. Thanos extends Prometheus by adding global query view, unlimited storage, and downsampling capabilities.

Identifying the Symptom: Block Overlaps

When using Thanos, you might encounter an error message stating: compaction: block overlaps detected. This symptom indicates that there are overlapping blocks in your Thanos setup, which can disrupt the compaction process and lead to data inconsistencies.

Explaining the Issue: Block Overlaps

Block overlaps occur when two or more blocks in Thanos have overlapping time ranges. This can happen due to misconfigured retention settings or improper block uploads. Overlapping blocks can cause issues during the compaction process, as Thanos expects blocks to have distinct time ranges.

Root Cause Analysis

The primary cause of block overlaps is often related to retention settings that are not properly configured. This can lead to blocks being retained longer than necessary, causing overlaps. Additionally, manual interventions or errors during block uploads can also result in overlaps.

Steps to Resolve Block Overlaps

To resolve block overlaps in Thanos, follow these steps:

Step 1: Identify Overlapping Blocks

Use the Thanos tool to list all blocks and identify overlaps. Run the following command:

thanos tools bucket inspect --objstore.config-file=

This command will help you inspect the blocks and identify any overlaps.

Step 2: Adjust Retention Settings

Review and adjust your retention settings to ensure that blocks are not retained longer than necessary. Check your Prometheus and Thanos configurations to ensure they align with your data retention policies.

Step 3: Manually Resolve Overlapping Blocks

If overlaps are detected, you may need to manually delete or merge overlapping blocks. Use the following command to delete a specific block:

thanos tools bucket rm --objstore.config-file= --id=

Ensure you have backups before performing deletions.

Step 4: Re-run Compaction

After resolving overlaps, re-run the compaction process to ensure that blocks are correctly compacted. This can be done by restarting the Thanos compactor component.

Additional Resources

For more information on Thanos and its configuration, refer to the official Thanos documentation. You can also explore the Thanos GitHub repository for community support and updates.