From owner-freebsd-questions@FreeBSD.ORG  Fri Mar 30 13:00:51 2012
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Date: Fri, 30 Mar 2012 13:00:51 +0000
From: Alexander Best <arundel@freebsd.org>
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Subject: question regarding geom labels
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hi there,

i have a question regarding a label for a swap partition. when should i do the
labeling? after or before creating the partition scheme?

when i label before creating the partition scheme, likes this:

glabel label -v swap /dev/da0
gpart create -s GPT /dev/da0

i get the following warning:

GEOM: da1: the secondary GPT header is not in the last LBA.

which is obvious, because the label is being written into the last LBA and thus
the backup GPT header gets written into the last-1 LBA.

if i create the partitioning scheme before labeling the device, like this:

gpart create -s GPT /dev/da0
glabel label -v swap /dev/da0

or

gpart create -s GPT /dev/da0
gpart add -t freebsd-swap /dev/da0
glabel label -v swap /dev/da0p1

the label gets written into da0 or da0p1 and is at constant risk of being
overwritten by userdata.

cheers.
alex