HOWTO: TrueNAS Scale: from 32gb USB to booting from mirrored larger enterprise SSD's, create add'l

# determine the drives you want to work on ie /dev/<drive>
# you could also remove your HDD's to shorten the list
lsblk -l

# set vars
# omit the /dev/ as the script below accounts for that.
bootdisk=sds
ssd1=sdl
ssd2=sdm
# optional: 4th partition
partitionpool=vm-pool

# we're dumping the current bootdrive partition data
# to a file, in the event you want to change sectors e.g. 512->4096
sfdisk --dump /dev/${bootdisk} > original.boot.disk.part.dump

###########################
# OPTIONAL if going to 4k sector size and/or want to use remaining free space as an additional pool
# USB sectors sizee 512 -> enterprise SSD sector size 4096
#
# 1. Dump current ssd partition table to grab last-lba for SSD
#
# sfdisk --dump /dev/${ssd1} > ssd.reference.dump
# cat ssd.reference.dump
#
#
# 2. edit the working dump with the SSD last-lba
#    divide all sector start/size by 4, rounding up to whole numbers
#    make sure the 'start' + 'size' does not exceed 'start' of the next partition
#
# nano original.boot.disk.part.dump
#
# 3. save
#
# /OPTIONAL
###########################
# edit sectors if you'd like, otherwise, move on
sfdisk --force /dev/${ssd1} < original.boot.disk.part.dump
sfdisk --force /dev/${ssd2} < original.boot.disk.part.dump

# attaching the 3rd partition to the boot-pool
zpool attach boot-pool ${bootdisk}3 ${ssd1}3
zpool attach boot-pool ${bootdisk}3 ${ssd2}3

# copy files from bootdisk,1 to drive1,1 & drive2,1
dd if=/dev/${bootdisk}1 of=/dev/${ssd1}1 status=progress
dd if=/dev/${bootdisk}1 of=/dev/${ssd2}1 status=progress

# copy files from bootdisk,1 to drive1,2 & drive2,2
# these 2 lines may be unnecessary, as I still had to copy efi files further down
dd if=/dev/${bootdisk}2 of=/dev/${ssd1}2 status=progress
dd if=/dev/${bootdisk}2 of=/dev/${ssd2}2 status=progress

# prep dirs needed for copying EFI partition
mkdir -p /mnt/${bootdisk}2/
mkdir -p /mnt/${ssd1}2/
mkdir -p /mnt/${ssd2}2/

# grub can have issues with installing here
# set the filesystem to fat32 for drive1,2 & drive2,2
mkfs.vfat /dev/${ssd1}2
mkfs.vfat /dev/${ssd2}2

# mount necessary dirs
mount /dev/${bootdisk}2 /mnt/${bootdisk}2/
mount /dev/${ssd1}2 /mnt/${ssd1}2/
mount /dev/${ssd2}2 /mnt/${ssd2}2/

# copy contents
cp -r /mnt/${bootdisk}2/ /mnt/{ssd1}2/
cp -r /mnt/${bootdisk}2/ /mnt/{ssd2}2/

# confirm resilvering is complete before detaching USB from boot-pool
watch -n 5 -d zpool status boot-pool

# offline and remove original bootdisk from the pool
zpool offline boot-pool ${bootdisk}3
zpool detach boot-pool ${bootdisk}3

###########################
# OPTIONAL: create a new SSD partitions and mirrored pool#
# 1. create partition on SSD1
# fdisk /dev/${ssd1}
# <input> n <press enter>
# <press enter to input defaults and create 4th partition>
# <input> w <press enter>
#
# 2. create partition on SSD2
# fdisk /dev/${ssd2}
# <input> n <press enter>
# <press enter to input defaults and create 4th partition>
# <input> w <press enter>
#
# 3. create mirrored pool from 4th partition and export to see in TrueNAS CLI/GUI
# zpool create ${partitionpool} /dev/${ssd1}4 /dev/${ssd2}4
# zpool export ${partitionpool}
#
# /OPTIONAL
###########################