# ZFS geli and 512b drives



## johnnyx (Mar 25, 2012)

hi community,
I am planning to give *F*ree*BSD* a go and wanted to go directly with zfs and geli as it seems really good.

I have already followed many articles here in the forum about zfs+geli, but they all seem to be about the new 4k drives.

I myself have 4 512b drives (each 1TB) around and wanted to make a two-mirror setup and also use geli for encryption. So when reading all the articles here for 4k drives, geli should use 4096b sector size, but what geli sector size is recommended for 512b drives in terms of speed/throughput. I need to get the best performance out of it, so i would really like to know what you people recommend on those old drives and how to align them properly.

Johnny.


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## phoenix (Mar 25, 2012)

If you ever see yourself replacing a drive in the pool, whether it be for larger ones, or because one died, then go with a 4 KB sector size in GELI, which will give an *ashift* setting for the vdev (and thus pool) of *12*.

Performance impact of using 4 KB writes on a 0.5 KB disk will be negligible.  But future-proofing impact will be huge!

While you can (in theory) add a 4 KB disk to a 0.5 KB (aka *ashift=9*) pool, performance will be affected for any non-aligned reads/writes.

To keep things safe, all new pools should be created with *ashift=12*.


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## johnnyx (Mar 25, 2012)

So apart from future plans, what do I now with 512b disks?


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