gpart before ZPOOL ?
reddit / freebsd

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cmic37 · 2020-11-11 18:10

(zfs/zpool noob...).

what is the difference between those 2 configs? I surmise gpart create
is not usefull, but...

first config:

`#gpart create -s gpt ada1`
`#zpool create poola ada1`


cleanup:
`#zpool destroy poola`
`#gpart destroy ada1`


second config:

`#zpool create poola ada1`

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meatmechdriver · 2020-11-11 18:20

The first config puts an empty guid partition table on the disk, the
second doesn't.. in both cases the pool is using the entire ada1 disk
and you've not put anything useful in the GPT.

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cmic37 · 2020-11-11 22:17

ok. There is no need to create something with GPT.
And, considerintg config 1, if i had written something on ada1, zpool
would have
zap/overwrite it, isn't it ?

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meatmechdriver · 2020-11-11 22:46

In this case yes, because ZFS doesn't use the GPT and EFI/BIOS can't
directly use a zpool dev anyway

I'm fairly certain that zpool labels are intentionally located away
from the sectors used for boot and partition schemes, so I don't
expect your GPT would be zapped.

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bsdimp · 2020-11-12 04:17

While there's no need, it's usually a really good idea to put a GPT on
the disk and use a partition that spans the drive. This gives you the
maximum flexibility, ensure that the boot loader can see it properly
and also is maximally compatible with lots of weird UEFI systems that
seem to randomly barf when there is no GPT.

While ZFS doesn't use GPT or know about it. The FreeBSD boot loader
does know about ZFS, but has/had bugs when the zpool was made up of
entire disks in some cases (though I'm struggling to enumerate exactly
which cases).