FreeBSD 9.2 のホストを 10.1 に更新する。基本的には freebsd-update で問題ない。

$ sudo freebsd-update -r 10.1-RELEASE upgrade
Password:
Looking up update.FreeBSD.org mirrors... 5 mirrors found.
Fetching metadata signature for 9.2-RELEASE from update4.freebsd.org... done.
Fetching metadata index... done.
Fetching 2 metadata patches.. done.
Applying metadata patches... done.
Inspecting system... done.

The following components of FreeBSD seem to be installed:
kernel/generic world/base

The following components of FreeBSD do not seem to be installed:
src/src world/doc world/games

Does this look reasonable (y/n)? y

Fetching metadata signature for 10.1-RELEASE from update4.freebsd.org... done.
Fetching metadata index... done.
Fetching 1 metadata patches. done.
Applying metadata patches... done.
Fetching 1 metadata files... done.
Inspecting system... done.
Fetching files from 9.2-RELEASE for merging... done.
Preparing to download files... done.
Fetching 10177 patches.....10....20....30....40....50....60....70....80....90....100....(略)....10010....10020....10030....10040....10050....10060....10070....10080....10090....10100....10110....10120....10130....10140....10150....10160....10170... done.
Applying patches... done.
Fetching 1719 files... done.
Attempting to automatically merge changes in files... done.

The following changes, which occurred between FreeBSD 9.2-RELEASE and
FreeBSD 10.1-RELEASE have been merged into /etc/group:

(略)

The following files will be removed as part of updating to 10.1-RELEASE-p3:
/boot/kernel/amd.ko
/boot/kernel/amd.ko.symbols
/boot/kernel/atadisk.ko
/boot/kernel/atadisk.ko.symbols
/boot/kernel/atapicam.ko
/boot/kernel/atapicam.ko.symbols
/boot/kernel/atapicd.ko
/boot/kernel/atapicd.ko.symbols
/boot/kernel/atapifd.ko
/boot/kernel/atapifd.ko.symbols
(略)

The following files will be updated as part of updating to 10.1-RELEASE-p3:
/.cshrc
/.profile
/COPYRIGHT
/bin/[
/bin/cat
(略)
/var/cache
/var/db/mergemaster.mtree
/var/empty
/var/yp/Makefile.dist
To install the downloaded upgrades, run "/usr/sbin/freebsd-update install".
$ sudo freebsd-update install
Password:
Installing updates...
Kernel updates have been installed.  Please reboot and run
"/usr/sbin/freebsd-update install" again to finish installing updates.
$ 

ここで再起動…したら起動途中で止まってしまった。

Trying to mount root from ufs:/dev/ada0p2 [rw]...
mountroot: waiting for device /dev/ada0p2 ...
Mounting from ufs:/dev/ada0p2 failed with error 19.

Loader variables:
  vfs.root.mountfrom=ufs:/dev/ada0p2
  vfs.root.mountfrom.options=rw

Manual root filesystem specification
  : [options]
      Mount  using filesystem 
      and with the specified (optional) option list.

    eg. ufs:/dev/da0s1a
        zfs:tank
        cd9660:/dev/acd0 ro
          (which is equivalent to: mount -t cd9660 -o ro /dev/acd0 /)

?                 List valid disk boot devices
.                 Yield 1 second (for background tasks)
      Abort manual input

mountroot>

“?” を叩いて有効なデバイスの一覧を見ると、ada0p2 の代わりに da0p2 があったのでそれを入力したら起動した。

/dev/fstab を ada0p2 → da0p2, ada0p3 → da0p3 と書き換えて正常に起動することを確認。