Will TiKV write data slowly if the system disk is too slow?

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This topic has been translated from a Chinese forum by GPT and might contain errors.

Original topic: tikv写数据，如果系统盘过慢会导致写数据很慢吗？

| username: lindoubled

TiDB version: 5.3.0

The server has two disks: a data disk and a system disk.

TiKV: deployed on the data disk, SSD

Linux kernel: deployed on the system disk, HDD using RAID1 mode

Question:
The data disk is very fast, but the system disk is very slow. Will this affect TiKV’s performance when writing data to the disk?
Or will TiKV use the system disk when writing data?

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| username: xfworld | Original post link

During the installation of TiDB, the system’s default temporary swap partition has been removed, and it directly uses memory, so it is no longer affected by the system disk.

The strategy of partitioning is definitely correct, but TiKV recommends NVMe. Regular SSDs will still have IO bottlenecks under high concurrency scenarios.

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| username: lindoubled | Original post link

Yes, they all use the PCIe bus.

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| username: lindoubled | Original post link

Look at this, if the write latency of the sda system disk increases, it will cause the IO utilization to rise and the IOPS to drop.

Both sdb and sdc are data disks.

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| username: xfworld | Original post link

Are SSDs and HDDs connected through a RAID card, or are they directly physically connected? It would be best to separate this as well…

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| username: lindoubled | Original post link

Separated

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| username: 履霜知冰 | Original post link

Personally, I don’t think it will affect TiKV’s performance. TiKV mainly uses memory, and the performance of the system disk usually does not directly affect memory read and write operations.

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| username: Meditator | Original post link

If the TiDB component’s logs and data files are not on the system disk, there will be no impact.

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| username: system | Original post link

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