Preparation

Disable Secure Boot. ZFS modules can not be loaded if Secure Boot is enabled.
Download a variant of Rocky Linux 8.5 Live ISO and boot from it.
Set root password or /root/.ssh/authorized_keys.

Start SSH server:

echo PermitRootLogin yes >> /etc/ssh/sshd_config
systemctl restart sshd

Connect from another computer:
```
ssh root@192.168.1.19
```
Temporarily set SELinux to permissive in live environment:
```
setenforce 0
```
SELinux will be enabled on the installed system.

Optional: If mirror speed is slow, you can manually pick a fixed mirror from mirrorlist and apply it:

sed -i 's|^mirrorlist=|#mirrorlist=|g' /etc/yum.repos.d/*
sed -i 's|^#baseurl=|baseurl=|g' /etc/yum.repos.d/*
sed -i 's|dl.rockylinux.org/$contentdir|mirrors.sjtug.sjtu.edu.cn/rocky|g' /etc/yum.repos.d/*

Add ZFS repo:

source /etc/os-release
RHEL_ZFS_REPO=https://zfsonlinux.org/epel/zfs-release.el${VERSION_ID/./_}.noarch.rpm
dnf install -y $RHEL_ZFS_REPO

Install ZFS packages:

dnf install -y epel-release
dnf config-manager --disable zfs
dnf config-manager --enable zfs-kmod
dnf install -y zfs

Load kernel modules:
```
modprobe zfs
```

Install helper script and partition tool:

rpm -ivh --nodeps https://dl.fedoraproject.org/pub/fedora/linux/releases/35/Everything/x86_64/os/Packages/a/arch-install-scripts-24-2.fc35.noarch.rpm
dnf install -y gdisk dosfstools

Set RHEL version:
```
INST_RHEL_VER=8
```
Unique pool suffix. ZFS expects pool names to be unique, therefore it’s recommended to create pools with a unique suffix:
```
INST_UUID=$(dd if=/dev/urandom bs=1 count=100 2>/dev/null | tr -dc 'a-z0-9' | cut -c-6)
```
Identify this installation in ZFS filesystem path:
```
INST_ID=rhel
```
Target disk

List available disks with:
```
ls /dev/disk/by-id/*
```
If using virtio as disk bus, use /dev/disk/by-path/*.

Declare disk array:
```
DISK='/dev/disk/by-id/ata-FOO /dev/disk/by-id/nvme-BAR'
```
For single disk installation, use:
```
DISK='/dev/disk/by-id/disk1'
```
Choose a primary disk. This disk will be used for primary EFI partition, default to first disk in the array:
```
INST_PRIMARY_DISK=$(echo $DISK | cut -f1 -d\ )
```
Set vdev topology, possible values are:
- (not set, single disk or striped; no redundancy)
- mirror
- raidz1
- raidz2
- raidz3
```
INST_VDEV=
```
This will create a single vdev with the topology of your choice. It is also possible to manually create a pool with multiple vdevs, such as:
```
zpool create --options \
      poolName \
      mirror sda sdb \
      raidz2 sdc ... \
      raidz3 sde ... \
      spare  sdf ...
```
Notice the cost of parity when using RAID-Z. See here and here.

For boot pool, which must be readable by GRUB, mirrored vdev should always be used for maximum redundancy. This guide will use mirrored bpool for multi-disk setup.

Refer to zpoolconcepts and zpool-create man pages for details.
Set partition size:

Set ESP size:
```
INST_PARTSIZE_ESP=2 # in GB
```
Set boot pool size. To avoid running out of space while using boot environments, the minimum is 4GB. Adjust the size if you intend to use multiple kernel/distros:
```
INST_PARTSIZE_BPOOL=4
```
Set swap size. It’s recommended to setup a swap partition. If you intend to use hibernation, the minimum should be no less than RAM size. Skip if swap is not needed:
```
INST_PARTSIZE_SWAP=8
```
Root pool size, use all remaining disk space if not set:
```
INST_PARTSIZE_RPOOL=
```