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Date:      Fri, 1 May 2020 11:51:00 -0700
From:      David Christensen <dpchrist@holgerdanske.com>
To:        freebsd-questions@freebsd.org
Subject:   Re: Mounting from ufs:/dev/ad2s1a failed with error 19.
Message-ID:  <e259057e-6952-5609-06b2-c5847b10848b@holgerdanske.com>
In-Reply-To: <20200501085510.9ef376bb.freebsd@edvax.de>
References:  <4348B2AE-3E30-4345-8883-EAEA53A59220@kukulies.org> <0D1F4392-C646-42C8-9DB3-50F93236A6DC@kukulies.org> <20200501051126.a41ff1cd.freebsd@edvax.de> <10b538ce-7b4d-22c1-dbde-60672244422e@holgerdanske.com> <20200501085510.9ef376bb.freebsd@edvax.de>

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On 2020-04-30 23:55, Polytropon wrote:
> On Thu, 30 Apr 2020 22:42:47 -0700, David Christensen wrote:
>> On 2020-04-30 20:11, Polytropon wrote:
>>> On Thu, 30 Apr 2020 20:29:14 +0200, Christoph Kukulies wrote:
>>>> Could solve it myself: bootet back to usb drive, mounted
>>>> /dev/ada0s1 /mnt and edited /mnt/etc/fstab to the correct
>>>> mount device.
>>>> There were ada2s1 for / and another ada2 device for swap.
>>>> Changed that to ada0s1 and now the system boots fine.
>>>
>>> If you can, use labels to avoid those kinds of problem. :-)
>>>
>>> https://www.freebsd.org/doc/handbook/geom-glabel.html
>>
>> Is there a FreeBSD labeling solution, or any other identifier solution
>> that avoids using device nodes, for the combination BIOS, MBR, GELI, and
>> ZFS?
> 
> For this constellation, probably glabel is the convenient
> tool: "glabel label <name> <device>", and then in the "zpool
> create" command use gpt/<name> indead of the device name.
> 
> I have no idea of why MBR should be involved here (as you
> want to use ZFS)...
> 
> Documentation:
> 
> 	https://www.freebsd.org/doc/handbook/zfs-quickstart.html
> 
> As the example shows, there is no MBR-related step involved.
> ZFS can manage devices just fine by itself. However, today's
> suggestion is to always use gpart (with -t freebsd-zfs for
> use with ZFS), so that's probably the best way to go.
> 
> Here is some specific inspiration that also includes the
> use of GELI:
> 
> 	https://blog.haraschak.com/from-dev-to-label/
> 
> So if I understand this correctly, the suggested approach
> is to use -l <label> in the "gpart add -t freebbsd-zfs"
> step for each disk, and then using those labels as mentioned
> above. The GELI partitions should then bear that name
> <label>.eli instead of the device name <device>.eli.
> 
> 
> 
>> And, that works if I use dd(1) to copy the raw system disk
>> contents from one device to another -- ATA drive, USB drive, SD card, etc.?
> 
> That probably depends on the source and target size, as if I
> remember correctly, labels are stored at the "logical end"
> of the device (last sector or block). However, labels are not
> supposed to be "cloned" that way. A typical solution is to
> prepare the target media using the appropriate tools (like
> gpart, maybe newfs), and then transfering the data. For ZFS,
> always use ZFS's native tools for that; for UFS, dump and
> restore are very convenient (and can deal with the case of
> non-matching sizes).

Thanks for the reply.


I have a mix of computers of varying ages.  Some are BIOS, some are 
early EFI/UEFI, some are recent UEFI.  All have firmware quirks.


I like being able to move my system images (binary data) from one device 
to another device and/or to move my system drives (devices) from one 
computer to another computer, and have everything "just work".


The combination of BIOS and MBR gives me the best results for the above 
constraints and goals.


When building a FreeBSD system disk, I use the FreeBSD installer and 
select "Partitioning" of  "Auto (ZFS)".  For example, here is my SOHO 
server.  The system drive (ada0) is an Intel SSD 520 Series 60 GB with a 
14g FreeBSD slice (ada0s1) containing a 2g ZFS boot partition (ada0s1a), 
a 2g GELI swap partition (ada0s1b), and a 10g GELI ZFS root partition 
(ada0s1d) (the 42g slice ada0s2 is a GELI/ ZFS cache for the data drives):

2020-05-01 10:57:34 toor@f3 ~
# gpart show -p ada0 ada0s1
=>       63  117231345    ada0  MBR  (56G)
          63       1985          - free -  (993K)
        2048   29360128  ada0s1  freebsd  [active]  (14G)
    29362176   87869232  ada0s2  freebsd  (42G)

=>       0  29360128   ada0s1  BSD  (14G)
          0   4194304  ada0s1a  freebsd-zfs  (2.0G)
    4194304   4194304  ada0s1b  freebsd-swap  (2.0G)
    8388608  20971520  ada0s1d  freebsd-zfs  (10G)


Looking at the last sectors of the first slice and the three partitions, 
they all contain data.  So, if I use glabel(8) to label them, things 
will break.


It sounds like I need to hack the FreeBSD installer to leave room at the 
end of the FreeBSD slice, to leave room at the end of each partition 
(does glabel work for swap?), to invoke glabel(8) with the right 
arguments to create labels, and to adjust all the other commands ('zpool 
create ...' , swap?) to use the labels while building the system image (?).


David



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