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This topic has been translated from a Chinese forum by GPT and might contain errors.Original topic: 磁盘超过90%
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username: 等一分钟
In which situations must the TiKV node data disk of TiDB be expanded when it exceeds 90%?
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username: 等一分钟
Sometimes it times out 90%, which affects the use of the cluster. However, my node is currently around 3TB, with 90% still having 300GB. Do I still need to expand?
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username: 
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username: When disk space exceeds 80%, it’s time to consider adding more space. At 90%, it’s like being roasted over a fire 
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username: 
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username: In any situation where it exceeds 90%, expansion is necessary. Don’t worry about the cost.
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username: It mainly depends on the data growth rate. When requesting resources, it’s best to provide an expected time frame for 100% capacity.
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username: Generally, you should consider scaling up when it reaches 80%. If it’s a default deployment, it seems like 5% of the space is reserved. Deleting that file can free up some disk space.
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username: - Performance Impact: When the data disk is nearly full, disk read/write performance may be affected, leading to a decline in TiKV node performance. This can severely impact the database’s response speed and stability.
- Data Migration: Data in the TiKV cluster requires frequent migration, scheduling, and compaction operations. When disk space is tight, these operations may be restricted, affecting the overall data processing capability.
- Fault Recovery: If the data disk is very close to saturation, data scheduling and balancing may become more difficult after a node failure, making it challenging to effectively migrate and replicate data.
- Future Growth Needs: If the data disk usage is already close to 90%, the trend of future data growth may soon lead to insufficient disk space. Therefore, considering expansion early is a wise choice.
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username: Overall, it is proportional. Smaller total amounts grow more slowly, while larger total amounts grow faster. 80% is a critical value, and sudden situations need to be considered.
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username: If it has been used normally for ten years and only then exceeds 90%, with a total capacity of 3TB and 300GB remaining, there is no need to rush to expand capacity within a month or two. What about a year later?
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username: You can also look at the remaining space and growth trends.
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username: Only new operations personnel would ask such a question, right? Who would wait until their disk is 90% full without expanding it, waiting for a crash to take the blame?
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username: 
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username: What are you waiting for? If something goes wrong, you’ll take the blame.
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username: Don’t wait, you’ll have to take the blame if something goes wrong.
There is a premise, 90%, and more than 300GB, otherwise who would ask such a brainless question?