146 lines
3.9 KiB
ReStructuredText
146 lines
3.9 KiB
ReStructuredText
.. highlight:: sh
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Recovery
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======================
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.. contents:: Table of Contents
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:local:
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GRUB Tips
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-------------
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Boot from GRUB rescue
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~~~~~~~~~~~~~~~~~~~~~~~
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If bootloader file is damaged, it's still possible
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to boot computer with GRUB rescue image.
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This section is also applicable if you are in
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``grub rescue>``.
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#. On another computer, generate rescue image with::
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pacman -S --needed mtools libisoburn grub
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grub-install
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grub-mkrescue -o grub-rescue.img
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dd if=grub-rescue.img of=/dev/your-usb-stick
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Boot computer from the rescue media.
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Both legacy and EFI mode are supported.
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Or `download generated GRUB rescue image <https://nu8.org/pages/projects/bieaz/#grub-rescue-images>`__.
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#. List available disks with ``ls`` command::
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grub> ls (hd # press tab
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Possible devices are:
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hd0 hd1 hd2 hd3
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#. List partitions by pressing tab key:
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.. code-block:: text
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grub> ls (hd0 # press tab
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Possible partitions are:
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Device hd0: No known filesystem detected - Sector size 512B - Total size 20971520KiB
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Partition hd0,gpt1: Filesystem type fat - Label `EFI', UUID 0DF5-3A76 - Partition start at 1024KiB - Total size 1048576KiB
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Partition hd0,gpt2: No known filesystem detected - Partition start at 1049600KiB - Total size 4194304KiB
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- If boot pool is encrypted:
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Unlock it with ``cryptomount``::
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grub> insmod luks
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grub> cryptomount hd0,gpt2
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Attempting to decrypt master key...
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Enter passphrase for hd0,gpt2 (af5a240e13e24483acf02600d61e0f36):
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Slot 1 opened
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Unlocked LUKS container is ``(crypto0)``:
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.. code-block:: text
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grub> ls (crypto0)
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Device crypto0: Filesystem type zfs - Label `bpool_ip3tdb' - Last modification
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time 2021-05-03 12:14:08 Monday, UUID f14d7bdf89fe21fb - Sector size 512B -
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Total size 4192256KiB
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- If boot pool is not encrypted:
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.. code-block:: text
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grub> ls (hd0,gpt2)
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Device hd0,gpt2: Filesystem type zfs - Label `bpool_ip3tdb' - Last modification
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time 2021-05-03 12:14:08 Monday, UUID f14d7bdf89fe21fb - Sector size 512B -
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Total size 4192256KiB
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#. List boot environments nested inside ``bpool/$INST_ID/BOOT``::
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grub> ls (crypto0)/sys/BOOT
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@/ default/ be0/
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#. Instruct GRUB to load configuration from ``be0`` boot environment::
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grub> prefix=(crypto0)/sys/BOOT/be0/@/grub
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grub> configfile $prefix/grub.cfg
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#. GRUB menu should now appear.
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#. After entering system, reinstall GRUB.
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Switch GRUB prefix when disk fails
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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If you are using LUKS encrypted boot pool with multiple disks,
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the primary disk failed, GRUB will fail to load configuration.
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If there's still enough redundancy for the boot pool, try fix
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GRUB with the following method:
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#. Ensure ``Slot 1 opened`` message
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is shown
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.. code-block:: text
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Welcome to GRUB!
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error: no such cryptodisk found.
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Attempting to decrypt master key...
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Enter passphrase for hd0,gpt2 (c0987ea1a51049e9b3056622804de62a):
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Slot 1 opened
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error: disk `cryptouuid/47ed1b7eb0014bc9a70aede3d8714faf' not found.
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Entering rescue mode...
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grub rescue>
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If ``error: access denied.`` is shown,
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try re-enter password with::
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grub rescue> cryptomount hd0,gpt2
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#. Check prefix::
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grub rescue > set
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# prefix=(cryptouuid/47ed1b7eb0014bc9a70aede3d8714faf)/sys/BOOT/be0@/grub
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# root=cryptouuid/47ed1b7eb0014bc9a70aede3d8714faf
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#. Set correct ``prefix`` and ``root`` by replacing
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``cryptouuid/UUID`` with ``crypto0``::
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grub rescue> prefix=(crypto0)/sys/BOOT/default@/grub
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grub rescue> root=crypto0
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#. Boot GRUB::
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grub rescue> insmod normal
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grub rescue> normal
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GRUB should then boot normally.
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#. After entering system, edit ``/etc/fstab`` to promote
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one backup to ``/boot/efi``.
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#. Make the change to ``prefix`` and ``root``
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permanent by `reinstalling GRUB <#grub-installation>`__.
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