Date: Fri, 30 Mar 2012 08:43:00 -0600 (MDT) From: Warren Block <wblock@wonkity.com> To: Alexander Best <arundel@freebsd.org> Cc: freebsd-questions@freebsd.org Subject: Re: question regarding geom labels Message-ID: <alpine.BSF.2.00.1203300836580.57460@wonkity.com> In-Reply-To: <20120330130051.GA62102@freebsd.org> References: <20120330130051.GA62102@freebsd.org>
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On Fri, 30 Mar 2012, Alexander Best wrote: > 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. Right. Don't do that, the GPT backup header needs to be at the end of the physical device. If you're using that whole disk for swap, there's no need for a partition anyway. > 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. No. The swap device entered in /etc/fstab would be /dev/label/swap, which is one block smaller than da0p1. That's the last-block metadata, it's safe. But if the whole disk is for swap, skip the partitioning entirely.
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