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Date:      Thu, 30 Apr 2020 13:39:47 -0700
From:      David Christensen <>
Subject:   Re: Mounting from ufs:/dev/ad2s1a failed with error 19.
Message-ID:  <>
In-Reply-To: <>
References:  <> <>

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On 2020-04-30 11:29, 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.
> —
> Christoph
>> Am 30.04.2020 um 19:32 schrieb Christoph Kukulies <>:
>> I did a fresh install of FreeBSD 12.1 today on an older Amd 64 ASRock Board and was pleasantly surprised how smooth everything went.
>> Boot device was a Kingston SSD 240GB which was on AHCI port 2 and AHCI Port 0 was another disk. After the install I wanted to boot but boot failed. Since the live CD was still inserted at that point in time the system tried to boot the live CD for whatever reason.
>> After that I swapped the ports and connected the install drive to port 0 and made it the preferable boot device (in first order in the BIOS).
>> Now I’m getting a boot failure. The system boots into the
>> mountroot> prompt givin the above error as shown in the subject line:
>> Mounting from ufs:/dev/ad2s1a failed with error 19.
>> What’s wrong?

I believe the root cause problem is that your computer has BIOS 
firmware, your SSD and other disk are using the MBR partitioning scheme, 
and the FreeBSD installer, bootloader, system configuration files, etc., 
all use device nodes for identifying devices, stripes, and partitions 
when dealing with the BIOS and MBR case.

As we both have found, this combination breaks whenever device nodes 
change -- such as by adding, moving, or removing a device.  And, the fix 
is to edit /etc/fstab, to edit /boot/loader.conf if running GELI, and/or 
to delete /boot/zfs/zpool.cache if running ZFS.

(Linux implements PARTUUID's for the BIOS/MBR case [1].  I have been 
unable to figure out how to do this on FreeBSD.)



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