Chapter 10. Troubleshooting scrub and deep-scrub issues

Prequisites

1. A running Red Hat Ceph Storage cluster in a healthy state.
2. Root-level access to the node.

Procedure

1. Detect low measured IOPS reported by OSD bench during OSD boot-up and fallback to default IOPS setting defined for osd_mclock_max_capacity_iops_[hdd|ssd]. The fallback is triggered if the reported IOPS falls below a threshold determined by osd_mclock_iops_capacity_low_threshold_[hdd|ssd]. A cluster warning is also logged.

   Example:

   $ ceph config rm osd.X osd_mclock_max_capacity_iops_[hdd|ssd]

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2. [Optional]: Perform the following steps:

   1. For clusters already affected by the issue, remove the IOPS capacity setting on the OSD(s) before upgrading to the release with the fix by running the following command:

      Example:

      $ ceph config rm osd.X osd_mclock_max_capacity_iops_[hdd|ssd]

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   2. Set the osd_mclock_force_run_benchmark_on_init option for the affected OSD to true before the upgrade:

      Example:

      $ ceph config set osd.X osd_mclock_force_run_benchmark_on_init true

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      After upgrading to the release with this fix, the IOPS capacity reflects the default setting or the new one reported by the OSD bench.

3. [Optional]: Perform the following steps if you have already upgraded from 8 to 9 (after upgrade):

   1. If you were unable to perform the above steps before upgrade, you re-run the OSD bench again after upgrading by removing the osd_mclock_max_capacity_iops_[hdd|ssd] setting:

      Example:

      $ ceph config rm osd.X osd_mclock_max_capacity_iops_[hdd|ssd]

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   2. Set osd_mclock_force_run_benchmark_on_init to true.

      Example:

      $ ceph config set osd.X osd_mclock_force_run_benchmark_on_init true

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   3. Restart the OSD.

      After the OSD restarts, the IOPS capacity reflects the default setting or the new setting reported by the OSD bench.