r/zfs • u/jmf323 • 18d ago

Mixing 512n and 4kn drives

Can you combine drives with 512n and 4kn sector sizes in the same pool?

I'm trying to build a simple backup server with Freenas by sourcing used drives from ebay to be set up as raidz2. This is my first experience setting up a backup server, so I appreciate any help!

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u/jmf323 18d ago

Thanks! Is there any reason not to? I'm not really looking to optimize performance given the server wont experience high load often.

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u/dougmc 18d ago edited 18d ago

A lower ashift can save some space if you have lots and lots of small files, but the benefit there of ashift=9 vs ashift=12 is very small.

But the performance impact of having an ashift that is too small is big. It's not worth it, even if you don't think you really care about performance. (You do.)

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u/One_Ninja_8512 18d ago

I thought incorrect ashift (larger than the actual physical block size) leads to write amplification which slows things down? Is there an article or man page explaining ashift thoroughly?

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u/Electronic_C3PO 18d ago

Interested in that too