Debian Stretch Root on ZFS
Overview
Newer release available
See Debian Buster Root on ZFS for new installs.
Caution
This HOWTO uses a whole physical disk.
Do not use these instructions for dual-booting.
Backup your data. Any existing data will be lost.
System Requirements
Installing on a drive which presents 4KiB logical sectors (a “4Kn” drive) only works with UEFI booting. This not unique to ZFS. GRUB does not and will not work on 4Kn with legacy (BIOS) booting.
Computers that have less than 2 GiB of memory run ZFS slowly. 4 GiB of memory is recommended for normal performance in basic workloads. If you wish to use deduplication, you will need massive amounts of RAM. Enabling deduplication is a permanent change that cannot be easily reverted.
Support
If you need help, reach out to the community using the Mailing Lists or IRC at #zfsonlinux on Libera Chat. If you have a bug report or feature request related to this HOWTO, please file a new issue and mention @rlaager.
Contributing
Fork and clone: https://github.com/openzfs/openzfs-docs
Install the tools:
sudo apt install python3-pip pip3 install -r docs/requirements.txt # Add ~/.local/bin to your $PATH, e.g. by adding this to ~/.bashrc: PATH=$HOME/.local/bin:$PATH
Make your changes.
Test:
cd docs make html sensible-browser _build/html/index.html
git commit --signoff
to a branch,git push
, and create a pull request. Mention @rlaager.
Encryption
This guide supports two different encryption options: unencrypted and LUKS (full-disk encryption). ZFS native encryption has not yet been released. With either option, all ZFS features are fully available.
Unencrypted does not encrypt anything, of course. With no encryption happening, this option naturally has the best performance.
LUKS encrypts almost everything: the OS, swap, home directories, and anything else. The only unencrypted data is the bootloader, kernel, and initrd. The system cannot boot without the passphrase being entered at the console. Performance is good, but LUKS sits underneath ZFS, so if multiple disks (mirror or raidz topologies) are used, the data has to be encrypted once per disk.
Step 1: Prepare The Install Environment
1.1 Boot the Debian GNU/Linux Live CD. If prompted, login with the
username user
and password live
. Connect your system to the
Internet as appropriate (e.g. join your WiFi network).
1.2 Optional: Install and start the OpenSSH server in the Live CD environment:
If you have a second system, using SSH to access the target system can be convenient.
$ sudo apt update
$ sudo apt install --yes openssh-server
$ sudo systemctl restart ssh
Hint: You can find your IP address with
ip addr show scope global | grep inet
. Then, from your main machine,
connect with ssh user@IP
.
1.3 Become root:
$ sudo -i
1.4 Setup and update the repositories:
# echo deb http://deb.debian.org/debian stretch contrib >> /etc/apt/sources.list
# echo deb http://deb.debian.org/debian stretch-backports main contrib >> /etc/apt/sources.list
# apt update
1.5 Install ZFS in the Live CD environment:
# apt install --yes debootstrap gdisk dkms dpkg-dev linux-headers-amd64
# apt install --yes -t stretch-backports zfs-dkms
# modprobe zfs
The dkms dependency is installed manually just so it comes from stretch and not stretch-backports. This is not critical.
Step 2: Disk Formatting
2.1 If you are re-using a disk, clear it as necessary:
If the disk was previously used in an MD array, zero the superblock:
# apt install --yes mdadm
# mdadm --zero-superblock --force /dev/disk/by-id/scsi-SATA_disk1
Clear the partition table:
# sgdisk --zap-all /dev/disk/by-id/scsi-SATA_disk1
2.2 Partition your disk(s):
Run this if you need legacy (BIOS) booting:
# sgdisk -a1 -n1:24K:+1000K -t1:EF02 /dev/disk/by-id/scsi-SATA_disk1
Run this for UEFI booting (for use now or in the future):
# sgdisk -n2:1M:+512M -t2:EF00 /dev/disk/by-id/scsi-SATA_disk1
Run this for the boot pool:
# sgdisk -n3:0:+1G -t3:BF01 /dev/disk/by-id/scsi-SATA_disk1
Choose one of the following options:
2.2a Unencrypted:
# sgdisk -n4:0:0 -t4:BF01 /dev/disk/by-id/scsi-SATA_disk1
2.2b LUKS:
# sgdisk -n4:0:0 -t4:8300 /dev/disk/by-id/scsi-SATA_disk1
Always use the long /dev/disk/by-id/*
aliases with ZFS. Using the
/dev/sd*
device nodes directly can cause sporadic import failures,
especially on systems that have more than one storage pool.
Hints:
ls -la /dev/disk/by-id
will list the aliases.Are you doing this in a virtual machine? If your virtual disk is missing from
/dev/disk/by-id
, use/dev/vda
if you are using KVM with virtio; otherwise, read the troubleshooting section.If you are creating a mirror or raidz topology, repeat the partitioning commands for all the disks which will be part of the pool.
2.3 Create the boot pool:
# zpool create -o ashift=12 -d \
-o feature@async_destroy=enabled \
-o feature@bookmarks=enabled \
-o feature@embedded_data=enabled \
-o feature@empty_bpobj=enabled \
-o feature@enabled_txg=enabled \
-o feature@extensible_dataset=enabled \
-o feature@filesystem_limits=enabled \
-o feature@hole_birth=enabled \
-o feature@large_blocks=enabled \
-o feature@lz4_compress=enabled \
-o feature@spacemap_histogram=enabled \
-o feature@userobj_accounting=enabled \
-O acltype=posixacl -O canmount=off -O compression=lz4 -O devices=off \
-O normalization=formD -O relatime=on -O xattr=sa \
-O mountpoint=/ -R /mnt \
bpool /dev/disk/by-id/scsi-SATA_disk1-part3
You should not need to customize any of the options for the boot pool.
GRUB does not support all of the zpool features. See
spa_feature_names
in
grub-core/fs/zfs/zfs.c.
This step creates a separate boot pool for /boot
with the features
limited to only those that GRUB supports, allowing the root pool to use
any/all features. Note that GRUB opens the pool read-only, so all
read-only compatible features are “supported” by GRUB.
Hints:
If you are creating a mirror or raidz topology, create the pool using
zpool create ... bpool mirror /dev/disk/by-id/scsi-SATA_disk1-part3 /dev/disk/by-id/scsi-SATA_disk2-part3
(or replacemirror
withraidz
,raidz2
, orraidz3
and list the partitions from additional disks).The pool name is arbitrary. If changed, the new name must be used consistently. The
bpool
convention originated in this HOWTO.
2.4 Create the root pool:
Choose one of the following options:
2.4a Unencrypted:
# zpool create -o ashift=12 \
-O acltype=posixacl -O canmount=off -O compression=lz4 \
-O dnodesize=auto -O normalization=formD -O relatime=on -O xattr=sa \
-O mountpoint=/ -R /mnt \
rpool /dev/disk/by-id/scsi-SATA_disk1-part4
2.4b LUKS:
# apt install --yes cryptsetup
# cryptsetup luksFormat -c aes-xts-plain64 -s 512 -h sha256 \
/dev/disk/by-id/scsi-SATA_disk1-part4
# cryptsetup luksOpen /dev/disk/by-id/scsi-SATA_disk1-part4 luks1
# zpool create -o ashift=12 \
-O acltype=posixacl -O canmount=off -O compression=lz4 \
-O dnodesize=auto -O normalization=formD -O relatime=on -O xattr=sa \
-O mountpoint=/ -R /mnt \
rpool /dev/mapper/luks1
The use of
ashift=12
is recommended here because many drives today have 4KiB (or larger) physical sectors, even though they present 512B logical sectors. Also, a future replacement drive may have 4KiB physical sectors (in which caseashift=12
is desirable) or 4KiB logical sectors (in which caseashift=12
is required).Setting
-O acltype=posixacl
enables POSIX ACLs globally. If you do not want this, remove that option, but later add-o acltype=posixacl
(note: lowercase “o”) to thezfs create
for/var/log
, as journald requires ACLsSetting
normalization=formD
eliminates some corner cases relating to UTF-8 filename normalization. It also impliesutf8only=on
, which means that only UTF-8 filenames are allowed. If you care to support non-UTF-8 filenames, do not use this option. For a discussion of why requiring UTF-8 filenames may be a bad idea, see The problems with enforced UTF-8 only filenames.Setting
relatime=on
is a middle ground between classic POSIXatime
behavior (with its significant performance impact) andatime=off
(which provides the best performance by completely disabling atime updates). Since Linux 2.6.30,relatime
has been the default for other filesystems. See RedHat’s documentation for further information.Setting
xattr=sa
vastly improves the performance of extended attributes. Inside ZFS, extended attributes are used to implement POSIX ACLs. Extended attributes can also be used by user-space applications. They are used by some desktop GUI applications. They can be used by Samba to store Windows ACLs and DOS attributes; they are required for a Samba Active Directory domain controller. Note that`xattr=sa
is Linux-specific. <https://openzfs.org/wiki/Platform_code_differences>`__ If you move yourxattr=sa
pool to another OpenZFS implementation besides ZFS-on-Linux, extended attributes will not be readable (though your data will be). If portability of extended attributes is important to you, omit the-O xattr=sa
above. Even if you do not wantxattr=sa
for the whole pool, it is probably fine to use it for/var/log
.Make sure to include the
-part4
portion of the drive path. If you forget that, you are specifying the whole disk, which ZFS will then re-partition, and you will lose the bootloader partition(s).For LUKS, the key size chosen is 512 bits. However, XTS mode requires two keys, so the LUKS key is split in half. Thus,
-s 512
means AES-256.Your passphrase will likely be the weakest link. Choose wisely. See section 5 of the cryptsetup FAQ for guidance.
Hints:
If you are creating a mirror or raidz topology, create the pool using
zpool create ... rpool mirror /dev/disk/by-id/scsi-SATA_disk1-part4 /dev/disk/by-id/scsi-SATA_disk2-part4
(or replacemirror
withraidz
,raidz2
, orraidz3
and list the partitions from additional disks). For LUKS, use/dev/mapper/luks1
,/dev/mapper/luks2
, etc., which you will have to create usingcryptsetup
.The pool name is arbitrary. If changed, the new name must be used consistently. On systems that can automatically install to ZFS, the root pool is named
rpool
by default.
Step 3: System Installation
3.1 Create filesystem datasets to act as containers:
# zfs create -o canmount=off -o mountpoint=none rpool/ROOT
# zfs create -o canmount=off -o mountpoint=none bpool/BOOT
On Solaris systems, the root filesystem is cloned and the suffix is
incremented for major system changes through pkg image-update
or
beadm
. Similar functionality for APT is possible but currently
unimplemented. Even without such a tool, it can still be used for
manually created clones.
3.2 Create filesystem datasets for the root and boot filesystems:
# zfs create -o canmount=noauto -o mountpoint=/ rpool/ROOT/debian
# zfs mount rpool/ROOT/debian
# zfs create -o canmount=noauto -o mountpoint=/boot bpool/BOOT/debian
# zfs mount bpool/BOOT/debian
With ZFS, it is not normally necessary to use a mount command (either
mount
or zfs mount
). This situation is an exception because of
canmount=noauto
.
3.3 Create datasets:
# zfs create rpool/home
# zfs create -o mountpoint=/root rpool/home/root
# zfs create -o canmount=off rpool/var
# zfs create -o canmount=off rpool/var/lib
# zfs create rpool/var/log
# zfs create rpool/var/spool
The datasets below are optional, depending on your preferences and/or
software choices:
If you wish to exclude these from snapshots:
# zfs create -o com.sun:auto-snapshot=false rpool/var/cache
# zfs create -o com.sun:auto-snapshot=false rpool/var/tmp
# chmod 1777 /mnt/var/tmp
If you use /opt on this system:
# zfs create rpool/opt
If you use /srv on this system:
# zfs create rpool/srv
If you use /usr/local on this system:
# zfs create -o canmount=off rpool/usr
# zfs create rpool/usr/local
If this system will have games installed:
# zfs create rpool/var/games
If this system will store local email in /var/mail:
# zfs create rpool/var/mail
If this system will use Snap packages:
# zfs create rpool/var/snap
If you use /var/www on this system:
# zfs create rpool/var/www
If this system will use GNOME:
# zfs create rpool/var/lib/AccountsService
If this system will use Docker (which manages its own datasets & snapshots):
# zfs create -o com.sun:auto-snapshot=false rpool/var/lib/docker
If this system will use NFS (locking):
# zfs create -o com.sun:auto-snapshot=false rpool/var/lib/nfs
A tmpfs is recommended later, but if you want a separate dataset for /tmp:
# zfs create -o com.sun:auto-snapshot=false rpool/tmp
# chmod 1777 /mnt/tmp
The primary goal of this dataset layout is to separate the OS from user
data. This allows the root filesystem to be rolled back without rolling
back user data such as logs (in /var/log
). This will be especially
important if/when a beadm
or similar utility is integrated. The
com.sun.auto-snapshot
setting is used by some ZFS snapshot utilities
to exclude transient data.
If you do nothing extra, /tmp
will be stored as part of the root
filesystem. Alternatively, you can create a separate dataset for
/tmp
, as shown above. This keeps the /tmp
data out of snapshots
of your root filesystem. It also allows you to set a quota on
rpool/tmp
, if you want to limit the maximum space used. Otherwise,
you can use a tmpfs (RAM filesystem) later.
3.4 Install the minimal system:
# debootstrap stretch /mnt
# zfs set devices=off rpool
The debootstrap
command leaves the new system in an unconfigured
state. An alternative to using debootstrap
is to copy the entirety
of a working system into the new ZFS root.
Step 4: System Configuration
4.1 Configure the hostname (change HOSTNAME
to the desired
hostname).
# echo HOSTNAME > /mnt/etc/hostname
# vi /mnt/etc/hosts
Add a line:
127.0.1.1 HOSTNAME
or if the system has a real name in DNS:
127.0.1.1 FQDN HOSTNAME
Hint: Use nano
if you find vi
confusing.
4.2 Configure the network interface:
Find the interface name:
# ip addr show
# vi /mnt/etc/network/interfaces.d/NAME
auto NAME
iface NAME inet dhcp
Customize this file if the system is not a DHCP client.
4.3 Configure the package sources:
# vi /mnt/etc/apt/sources.list
deb http://deb.debian.org/debian stretch main contrib
deb-src http://deb.debian.org/debian stretch main contrib
deb http://security.debian.org/debian-security stretch/updates main contrib
deb-src http://security.debian.org/debian-security stretch/updates main contrib
deb http://deb.debian.org/debian stretch-updates main contrib
deb-src http://deb.debian.org/debian stretch-updates main contrib
# vi /mnt/etc/apt/sources.list.d/stretch-backports.list
deb http://deb.debian.org/debian stretch-backports main contrib
deb-src http://deb.debian.org/debian stretch-backports main contrib
# vi /mnt/etc/apt/preferences.d/90_zfs
Package: src:zfs-linux
Pin: release n=stretch-backports
Pin-Priority: 990
4.4 Bind the virtual filesystems from the LiveCD environment to the new
system and chroot
into it:
# mount --rbind /dev /mnt/dev
# mount --rbind /proc /mnt/proc
# mount --rbind /sys /mnt/sys
# chroot /mnt /bin/bash --login
Note: This is using --rbind
, not --bind
.
4.5 Configure a basic system environment:
# ln -s /proc/self/mounts /etc/mtab
# apt update
# apt install --yes locales
# dpkg-reconfigure locales
Even if you prefer a non-English system language, always ensure that
en_US.UTF-8
is available.
# dpkg-reconfigure tzdata
4.6 Install ZFS in the chroot environment for the new system:
# apt install --yes dpkg-dev linux-headers-amd64 linux-image-amd64
# apt install --yes zfs-initramfs
4.7 For LUKS installs only, setup crypttab:
# apt install --yes cryptsetup
# echo luks1 UUID=$(blkid -s UUID -o value \
/dev/disk/by-id/scsi-SATA_disk1-part4) none \
luks,discard,initramfs > /etc/crypttab
The use of
initramfs
is a work-around for cryptsetup does not support ZFS.
Hint: If you are creating a mirror or raidz topology, repeat the
/etc/crypttab
entries for luks2
, etc. adjusting for each disk.
4.8 Install GRUB
Choose one of the following options:
4.8a Install GRUB for legacy (BIOS) booting
# apt install --yes grub-pc
Install GRUB to the disk(s), not the partition(s).
4.8b Install GRUB for UEFI booting
# apt install dosfstools
# mkdosfs -F 32 -s 1 -n EFI /dev/disk/by-id/scsi-SATA_disk1-part2
# mkdir /boot/efi
# echo PARTUUID=$(blkid -s PARTUUID -o value \
/dev/disk/by-id/scsi-SATA_disk1-part2) \
/boot/efi vfat nofail,x-systemd.device-timeout=1 0 1 >> /etc/fstab
# mount /boot/efi
# apt install --yes grub-efi-amd64 shim
The
-s 1
formkdosfs
is only necessary for drives which present 4 KiB logical sectors (“4Kn” drives) to meet the minimum cluster size (given the partition size of 512 MiB) for FAT32. It also works fine on drives which present 512 B sectors.
Note: If you are creating a mirror or raidz topology, this step only installs GRUB on the first disk. The other disk(s) will be handled later.
4.9 Set a root password
# passwd
4.10 Enable importing bpool
This ensures that bpool
is always imported, regardless of whether
/etc/zfs/zpool.cache
exists, whether it is in the cachefile or not,
or whether zfs-import-scan.service
is enabled.
# vi /etc/systemd/system/zfs-import-bpool.service
[Unit]
DefaultDependencies=no
Before=zfs-import-scan.service
Before=zfs-import-cache.service
[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/sbin/zpool import -N -o cachefile=none bpool
[Install]
WantedBy=zfs-import.target
# systemctl enable zfs-import-bpool.service
4.11 Optional (but recommended): Mount a tmpfs to /tmp
If you chose to create a /tmp
dataset above, skip this step, as they
are mutually exclusive choices. Otherwise, you can put /tmp
on a
tmpfs (RAM filesystem) by enabling the tmp.mount
unit.
# cp /usr/share/systemd/tmp.mount /etc/systemd/system/
# systemctl enable tmp.mount
4.12 Optional (but kindly requested): Install popcon
The popularity-contest
package reports the list of packages install
on your system. Showing that ZFS is popular may be helpful in terms of
long-term attention from the distro.
# apt install --yes popularity-contest
Choose Yes at the prompt.
Step 5: GRUB Installation
5.1 Verify that the ZFS boot filesystem is recognized:
# grub-probe /boot
zfs
5.2 Refresh the initrd files:
# update-initramfs -u -k all
update-initramfs: Generating /boot/initrd.img-4.9.0-8-amd64
Note: When using LUKS, this will print “WARNING could not determine root device from /etc/fstab”. This is because cryptsetup does not support ZFS.
5.3 Workaround GRUB’s missing zpool-features support:
# vi /etc/default/grub
Set: GRUB_CMDLINE_LINUX="root=ZFS=rpool/ROOT/debian"
5.4 Optional (but highly recommended): Make debugging GRUB easier:
# vi /etc/default/grub
Remove quiet from: GRUB_CMDLINE_LINUX_DEFAULT
Uncomment: GRUB_TERMINAL=console
Save and quit.
Later, once the system has rebooted twice and you are sure everything is working, you can undo these changes, if desired.
5.5 Update the boot configuration:
# update-grub
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.9.0-8-amd64
Found initrd image: /boot/initrd.img-4.9.0-8-amd64
done
Note: Ignore errors from osprober
, if present.
5.6 Install the boot loader
5.6a For legacy (BIOS) booting, install GRUB to the MBR:
# grub-install /dev/disk/by-id/scsi-SATA_disk1
Installing for i386-pc platform.
Installation finished. No error reported.
Do not reboot the computer until you get exactly that result message. Note that you are installing GRUB to the whole disk, not a partition.
If you are creating a mirror or raidz topology, repeat the
grub-install
command for each disk in the pool.
5.6b For UEFI booting, install GRUB:
# grub-install --target=x86_64-efi --efi-directory=/boot/efi \
--bootloader-id=debian --recheck --no-floppy
5.7 Verify that the ZFS module is installed:
# ls /boot/grub/*/zfs.mod
5.8 Fix filesystem mount ordering
Until ZFS gains a systemd mount
generator, there are
races between mounting filesystems and starting certain daemons. In
practice, the issues (e.g.
#5754) seem to be
with certain filesystems in /var
, specifically /var/log
and
/var/tmp
. Setting these to use legacy
mounting, and listing them
in /etc/fstab
makes systemd aware that these are separate
mountpoints. In turn, rsyslog.service
depends on var-log.mount
by way of local-fs.target
and services using the PrivateTmp
feature of systemd automatically use After=var-tmp.mount
.
Until there is support for mounting /boot
in the initramfs, we also
need to mount that, because it was marked canmount=noauto
. Also,
with UEFI, we need to ensure it is mounted before its child filesystem
/boot/efi
.
rpool
is guaranteed to be imported by the initramfs, so there is no
point in adding x-systemd.requires=zfs-import.target
to those
filesystems.
For UEFI booting, unmount /boot/efi first:
# umount /boot/efi
Everything else applies to both BIOS and UEFI booting:
# zfs set mountpoint=legacy bpool/BOOT/debian
# echo bpool/BOOT/debian /boot zfs \
nodev,relatime,x-systemd.requires=zfs-import-bpool.service 0 0 >> /etc/fstab
# zfs set mountpoint=legacy rpool/var/log
# echo rpool/var/log /var/log zfs nodev,relatime 0 0 >> /etc/fstab
# zfs set mountpoint=legacy rpool/var/spool
# echo rpool/var/spool /var/spool zfs nodev,relatime 0 0 >> /etc/fstab
If you created a /var/tmp dataset:
# zfs set mountpoint=legacy rpool/var/tmp
# echo rpool/var/tmp /var/tmp zfs nodev,relatime 0 0 >> /etc/fstab
If you created a /tmp dataset:
# zfs set mountpoint=legacy rpool/tmp
# echo rpool/tmp /tmp zfs nodev,relatime 0 0 >> /etc/fstab
Step 6: First Boot
6.1 Snapshot the initial installation:
# zfs snapshot bpool/BOOT/debian@install
# zfs snapshot rpool/ROOT/debian@install
In the future, you will likely want to take snapshots before each upgrade, and remove old snapshots (including this one) at some point to save space.
6.2 Exit from the chroot
environment back to the LiveCD environment:
# exit
6.3 Run these commands in the LiveCD environment to unmount all filesystems:
# mount | grep -v zfs | tac | awk '/\/mnt/ {print $3}' | xargs -i{} umount -lf {}
# zpool export -a
6.4 Reboot:
# reboot
6.5 Wait for the newly installed system to boot normally. Login as root.
6.6 Create a user account:
# zfs create rpool/home/YOURUSERNAME
# adduser YOURUSERNAME
# cp -a /etc/skel/.[!.]* /home/YOURUSERNAME
# chown -R YOURUSERNAME:YOURUSERNAME /home/YOURUSERNAME
6.7 Add your user account to the default set of groups for an administrator:
# usermod -a -G audio,cdrom,dip,floppy,netdev,plugdev,sudo,video YOURUSERNAME
6.8 Mirror GRUB
If you installed to multiple disks, install GRUB on the additional disks:
6.8a For legacy (BIOS) booting:
# dpkg-reconfigure grub-pc
Hit enter until you get to the device selection screen.
Select (using the space bar) all of the disks (not partitions) in your pool.
6.8b UEFI
# umount /boot/efi
For the second and subsequent disks (increment debian-2 to -3, etc.):
# dd if=/dev/disk/by-id/scsi-SATA_disk1-part2 \
of=/dev/disk/by-id/scsi-SATA_disk2-part2
# efibootmgr -c -g -d /dev/disk/by-id/scsi-SATA_disk2 \
-p 2 -L "debian-2" -l '\EFI\debian\grubx64.efi'
# mount /boot/efi
Step 7: (Optional) Configure Swap
Caution: On systems with extremely high memory pressure, using a zvol for swap can result in lockup, regardless of how much swap is still available. This issue is currently being investigated in: https://github.com/zfsonlinux/zfs/issues/7734
7.1 Create a volume dataset (zvol) for use as a swap device:
# zfs create -V 4G -b $(getconf PAGESIZE) -o compression=zle \
-o logbias=throughput -o sync=always \
-o primarycache=metadata -o secondarycache=none \
-o com.sun:auto-snapshot=false rpool/swap
You can adjust the size (the 4G
part) to your needs.
The compression algorithm is set to zle
because it is the cheapest
available algorithm. As this guide recommends ashift=12
(4 kiB
blocks on disk), the common case of a 4 kiB page size means that no
compression algorithm can reduce I/O. The exception is all-zero pages,
which are dropped by ZFS; but some form of compression has to be enabled
to get this behavior.
7.2 Configure the swap device:
Caution: Always use long /dev/zvol
aliases in configuration
files. Never use a short /dev/zdX
device name.
# mkswap -f /dev/zvol/rpool/swap
# echo /dev/zvol/rpool/swap none swap discard 0 0 >> /etc/fstab
# echo RESUME=none > /etc/initramfs-tools/conf.d/resume
The RESUME=none
is necessary to disable resuming from hibernation.
This does not work, as the zvol is not present (because the pool has not
yet been imported) at the time the resume script runs. If it is not
disabled, the boot process hangs for 30 seconds waiting for the swap
zvol to appear.
7.3 Enable the swap device:
# swapon -av
Step 8: Full Software Installation
8.1 Upgrade the minimal system:
# apt dist-upgrade --yes
8.2 Install a regular set of software:
# tasksel
Note: This will check “Debian desktop environment” and “print server” by default. If you want a server installation, unselect those.
8.3 Optional: Disable log compression:
As /var/log
is already compressed by ZFS, logrotate’s compression is
going to burn CPU and disk I/O for (in most cases) very little gain.
Also, if you are making snapshots of /var/log
, logrotate’s
compression will actually waste space, as the uncompressed data will
live on in the snapshot. You can edit the files in /etc/logrotate.d
by hand to comment out compress
, or use this loop (copy-and-paste
highly recommended):
# for file in /etc/logrotate.d/* ; do
if grep -Eq "(^|[^#y])compress" "$file" ; then
sed -i -r "s/(^|[^#y])(compress)/\1#\2/" "$file"
fi
done
8.4 Reboot:
# reboot
Step 9: Final Cleanup
9.1 Wait for the system to boot normally. Login using the account you created. Ensure the system (including networking) works normally.
9.2 Optional: Delete the snapshots of the initial installation:
$ sudo zfs destroy bpool/BOOT/debian@install
$ sudo zfs destroy rpool/ROOT/debian@install
9.3 Optional: Disable the root password
$ sudo usermod -p '*' root
9.4 Optional: Re-enable the graphical boot process:
If you prefer the graphical boot process, you can re-enable it now. If you are using LUKS, it makes the prompt look nicer.
$ sudo vi /etc/default/grub
Add quiet to GRUB_CMDLINE_LINUX_DEFAULT
Comment out GRUB_TERMINAL=console
Save and quit.
$ sudo update-grub
Note: Ignore errors from osprober
, if present.
9.5 Optional: For LUKS installs only, backup the LUKS header:
$ sudo cryptsetup luksHeaderBackup /dev/disk/by-id/scsi-SATA_disk1-part4 \
--header-backup-file luks1-header.dat
Store that backup somewhere safe (e.g. cloud storage). It is protected by your LUKS passphrase, but you may wish to use additional encryption.
Hint: If you created a mirror or raidz topology, repeat this for
each LUKS volume (luks2
, etc.).
Troubleshooting
Rescuing using a Live CD
Go through Step 1: Prepare The Install Environment.
This will automatically import your pool. Export it and re-import it to get the mounts right:
For LUKS, first unlock the disk(s):
# apt install --yes cryptsetup
# cryptsetup luksOpen /dev/disk/by-id/scsi-SATA_disk1-part4 luks1
Repeat for additional disks, if this is a mirror or raidz topology.
# zpool export -a
# zpool import -N -R /mnt rpool
# zpool import -N -R /mnt bpool
# zfs mount rpool/ROOT/debian
# zfs mount -a
If needed, you can chroot into your installed environment:
# mount --rbind /dev /mnt/dev
# mount --rbind /proc /mnt/proc
# mount --rbind /sys /mnt/sys
# chroot /mnt /bin/bash --login
# mount /boot/efi
# mount -a
Do whatever you need to do to fix your system.
When done, cleanup:
# exit
# mount | grep -v zfs | tac | awk '/\/mnt/ {print $3}' | xargs -i{} umount -lf {}
# zpool export -a
# reboot
MPT2SAS
Most problem reports for this tutorial involve mpt2sas
hardware that
does slow asynchronous drive initialization, like some IBM M1015 or
OEM-branded cards that have been flashed to the reference LSI firmware.
The basic problem is that disks on these controllers are not visible to the Linux kernel until after the regular system is started, and ZoL does not hotplug pool members. See https://github.com/zfsonlinux/zfs/issues/330.
Most LSI cards are perfectly compatible with ZoL. If your card has this glitch, try setting ZFS_INITRD_PRE_MOUNTROOT_SLEEP=X in /etc/default/zfs. The system will wait X seconds for all drives to appear before importing the pool.
Areca
Systems that require the arcsas
blob driver should add it to the
/etc/initramfs-tools/modules
file and run
update-initramfs -u -k all
.
Upgrade or downgrade the Areca driver if something like
RIP: 0010:[<ffffffff8101b316>] [<ffffffff8101b316>] native_read_tsc+0x6/0x20
appears anywhere in kernel log. ZoL is unstable on systems that emit
this error message.
VMware
Set
disk.EnableUUID = "TRUE"
in the vmx file or vsphere configuration. Doing this ensures that/dev/disk
aliases are created in the guest.
QEMU/KVM/XEN
Set a unique serial number on each virtual disk using libvirt or qemu
(e.g. -drive if=none,id=disk1,file=disk1.qcow2,serial=1234567890
).
To be able to use UEFI in guests (instead of only BIOS booting), run this on the host:
$ sudo apt install ovmf
$ sudo vi /etc/libvirt/qemu.conf
Uncomment these lines:
nvram = [
"/usr/share/OVMF/OVMF_CODE.fd:/usr/share/OVMF/OVMF_VARS.fd",
"/usr/share/AAVMF/AAVMF_CODE.fd:/usr/share/AAVMF/AAVMF_VARS.fd"
]
$ sudo service libvirt-bin restart