Date: Thu, 22 Mar 2018 07:28:14 -0600 (MDT) From: Warren Block <wblock@wonkity.com> To: Victor Sudakov <vas@mpeks.tomsk.su> Cc: freebsd-questions@freebsd.org Subject: Re: Solved. Re: Dualboot and ZFS Message-ID: <alpine.BSF.2.21.1803220726210.5586@wonkity.com> In-Reply-To: <20180322012621.GA15678@admin.sibptus.transneft.ru> References: <VI1PR02MB1200C7F0066F361E60A6CBEDF6EB0@VI1PR02MB1200.eurprd02.prod.outlook.com> <20180115144747.GA65526@admin.sibptus.transneft.ru> <VI1PR02MB120018D174817F8FFB2981D5F6EB0@VI1PR02MB1200.eurprd02.prod.outlook.com> <20180115151526.GA66342@admin.sibptus.transneft.ru> <a7920f859b666cff48f4f73ee1b2f954@dweimer.net> <20180116034929.GB89443@admin.sibptus.transneft.ru> <20180131082738.GA46395@admin.sibptus.transneft.ru> <547e65d16ef16667f61d88463ca73079@roundcube.fjl.org.uk> <20180319025914.GA57490@admin.sibptus.transneft.ru> <alpine.BSF.2.21.1803210626040.85475@wonkity.com> <20180322012621.GA15678@admin.sibptus.transneft.ru>
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On Thu, 22 Mar 2018, Victor Sudakov wrote:
> Warren Block wrote:
>> On Mon, 19 Mar 2018, Victor Sudakov wrote:
>>>
>>> sysctl kern.geom.debugflags=0x10
>>
>> Please reconsider doing this without it being required. It means "allow
>> destroying mounted partitions" and is usually not necessary.
>
> It is recommended, or even required ("must") by the zfsboot(8) man page:
The vagueness here is from the "If the drive is currently in use". It
could easily be replaced with "If the user wants to destroy data from a
drive that is currently being used". I would argue that we should
remove or rewrite that, as it is misleading. Overwriting a drive that
is "in use" is generally exactly the opposite of what people want.
> EXAMPLES
> zfsboot is typically installed using dd(1). To install zfsboot on the
> ada0 drive:
>
> dd if=/boot/zfsboot of=/dev/ada0 count=1
> dd if=/boot/zfsboot of=/dev/ada0 iseek=1 oseek=1024
>
> If the drive is currently in use, the GEOM safety will prevent writes and
> must be disabled before running the above commands:
>
> sysctl kern.geom.debugflags=0x10
>
> zfsboot can also be installed in an MBR slice:
>
> gpart create -s mbr ada0
> gpart add -t freebsd ada0
> gpart create -s BSD ada0s1
> gpart bootcode -b /boot/boot0 ada0
> gpart set -a active -i 1 ada0
> dd if=/boot/zfsboot of=/dev/ada0s1 count=1
> dd if=/boot/zfsboot of=/dev/ada0s1 iseek=1 oseek=1024
>
>
>
>
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