Add KB for the issue volumes with lot of files take a long time to finish mounting
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PhanLe1010
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| When starting workload pod which uses Longhorn volumes, | ||
| observe in Longhorn UI that the Longhorn volumes are attached quickly | ||
| but it takes a long time for the volumes to finish mounting and workload to be able to start. |
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When starting a workload pod that uses Longhorn volumes,
the Longhorn UI shows that the Longhorn volumes are attached quickly,
but it takes a long time for the volumes to finish mounting and for the workload to be able to start.
| observe in Longhorn UI that the Longhorn volumes are attached quickly | ||
| but it takes a long time for the volumes to finish mounting and workload to be able to start. | ||
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| This issue only happens when Longhorn volumes that have many files/directories and the workload pod sets `fsGroup` in the `securityContext` similar to as below: |
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This issue only happens when the Longhorn volumes have many files/directories and securityContext.fsGroup is set in the workload pod as shown below:
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| ## Reason | ||
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| By default, when seeing `fsGroup` field, each time a volume is mounted, Kubernetes recursively `chown()` and `chmod()` all the files and directories inside the volume. |
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By default, when seeing the fsGroup field, each time a volume is mounted, Kubernetes recursively calls chown() and chmod() on all the files and directories inside the volume.
| When `fsGroupChangePolicy` is set to `OnRootMismatch`, if the root of the volume already has the correct permissions, | ||
| the recursive permission and ownership change will be skipped. | ||
| It means that if users don't change the `pod.spec.securityContext.fsGroup` between pod's startups, | ||
| K8s will only have to check the permissions and ownership of the root and the mounting process will be much faster compared to always recursively change the volumes' ownership and permissions. |
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compared to always recursively changing
…inish mounting` longhorn/longhorn#2131 Signed-off-by: Phan Le <phan.le@rancher.com>
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Catherine's review comments are addressed |
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@catherineluse can you review again? Thanks. |
longhorn/longhorn#2131