FreeNAS ZFS Benchmarks: 1 Data Drive

This benchmark have three pool configurations: Single drive, a 2-way mirror, and a 3-way mirror. Please see the previous posts on testing methology and hardware specifications, if you haven’t already.

I expect the single drive to have the best write performance, followed by the 2-way then 3-way mirror. I also expect the mirrors to have better read performance, as there’s more drives to read from. I also expect there to be a noticeable performance penalty for record sizes smaller than ZFS’s configured recordsize of 128k. I expect error margins of +/- 10%. The random reads/writes should get almost linearly better performance with the larger record sizes.

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ZFS: An explanation of different pool layouts

This post contains some examples and short descriptions of different ZFS pool layouts. I’m assuming you’re already familiar with the features of ZFS. If not, you may want to check out the Wikipedia article on ZFS.

General information

It’s recommended to never have more than 9 drives in a single vdev, as this will have a noticeable performance impact, especially when resilvering. Resilvering may become so slow that it’s likely you’ll lose additional drives while the process is running, potentially causing data loss. It’s therefore recommended to use multiple vdevs in the same pool when you want to use more than 9 drives.

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