[zfs-discuss] SSDs and Limiting Used Space

Niels de Carpentier niels at decarpentier.com
Sun Aug 18 12:57:55 EDT 2013

> Quoting Gordan Bobic <gordan.bobic at gmail.com> on Fri, Aug 16 15:49:
>> But what about the location of partition 9? From what I've been reading,
>> part9 is a GPT/EFI thing. It is not entirely clear whether the location
>> of
>> this partition is in any way relevant.
> I asked the same question back in March
> <https://groups.google.com/a/zfsonlinux.org/forum/?hl=en_US#!searchin/zfs-discuss/ZFS$20and$20GPT$20partitions$2C$20last$208$20MB/zfs-discuss/gedcS4rfoDg/yDnbuSn_h6EJ>
> and the short answer is "Partition #9 is created by the tools to be
> consistent with the Illumos behavior but is otherwise completely
> unused.". I've deleted it on a couple ZFS disks without any issues.

It is unused, but there is a good reason it's there.
The reason is padding, as different models/manufacturers of disks can have
slightly different sector counts.

Without the padding replacing the drive with a replacement that is 2
sectors smaller (But exactly the same advertised size) won't work.
So just leave it in place to avoid nasty surprises in the future.

Raid controllers often do something similar for the same reason.


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