# Disk Capacity Impact Pd Scheduling Performance Case Study Summary


![left](./student-guide/diagram/03-34-1.png)

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Under normal circumstances, the number of regions and leaders of each store should remain relatively stable and balanced. When drastic changes occur, performance fluctuations usually occur.

- Confirm from the Scheduler - Balance region event that the number of regions has changed due to the region scheduling initiated by the PD.

- Confirm from the Store Available Ratio that the free space of the store has exceeded the high-space-ratio watermark. At this time, the PD calculates the store score and adds the disk free space factor to open the difference in the store score below the watermark. The score monitor allows you to see how the score changes.

- Temporarily raise the high-space-ratio and low-space-ratio thresholds to resolve the issue since there is still plenty of free space.