Good value of maxConcurrentWrites for fast NVMe storage?

The default for maxConcurrentWrites is 2, and the docs say

Maximum number of concurrent write operations while syncing. Defaults to 2. Increasing this might increase or decrease disk performance, depending on the underlying storage.

Has anyone tried different values for an NVMe drive? I’m using a 1TB Samsung Evo 970 Plus on a modern high-end laptop. I am not looking for the perfect number, just a ballpark guess about what might be a reasonable value. Thanks

We just had this discussion recently, I can’t find the thread though.

I haven’t tested anything. However my opinion is still that it will have no effect at all. I haven’t yet seen any argument, why more concurrent write operations would make writing faster. And even if it did, I’d say that other operations like fsyncing are way more significant.

The discussion was likely

although I do not think that there are any specific benchmarks testing different values. The only thing certain is that too many or unlimited writes can lead to issues :grimacing:.

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Thank you for the links. Those are informative. From what I have read so far in those links, all the issues were related to slow storage devices and/or having no limit on maxConcurrentWrites.

With fast storage hardware, I may try a modest increase from 2 to something, but I definitely will not set it to unlimited.

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