Comment by abrookewood

5 days ago

Can someone provide details on this bit please? "Direct IO: Allows bypassing the ARC for reads/writes, improving performance in scenarios like NVMe devices where caching may hinder efficiency".

ARC is based in RAM, so how could it reduce performance when used with NVMe devices? They are fast, but they aren't RAM-fast ...

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abrookewood

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nolist_policy  5 days ago

Because with a (ARC) cache you have to copy from the app to the cache and then dma to disk. With direct io you can dma directly from the app ram to the disk.