Disk Partitioning

Overview

Before creating a ZFS pool, you may need to partition disks. This guide covers partitioning the internal NVMe to coexist with ext4 root.

When to Partition

Scenario	Partition Needed
Dedicated disk for ZFS	No - use whole disk
ZFS alongside ext4 root	Yes - create partition for ZFS
Adding spare space from boot disk	Yes - create partition from free space

For this setup:

• Internal NVMe (2TB): Partitioned - ext4 root + ZFS partition
• Secondary NVMe (4TB): Whole disk for ZFS

Identify Disks

List block devices:

lsblk

Example output:

NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
nvme0n1     259:0    0   1.8T  0 disk
├─nvme0n1p1 259:1    0   512M  0 part /boot/efi
├─nvme0n1p2 259:2    0     1G  0 part /boot
└─nvme0n1p3 259:3    0   500G  0 part /
nvme1n1     259:4    0   3.6T  0 disk

Get persistent disk IDs:

ls -la /dev/disk/by-id/ | grep nvme

Use disk IDs

Always reference disks by /dev/disk/by-id/ paths. Device names like /dev/nvme0n1 can change between boots.

Plan Partition Layout

Target layout for internal NVMe:

Partition	Size	Purpose
p1	512 MB	EFI System
p2	1 GB	/boot
p3	500 GB - 1 TB	/ (ext4 root)
p4	Remaining	ZFS pool member

Partition Internal NVMe

Check Free Space

sudo fdisk -l /dev/nvme0n1

If the disk has unallocated space after the root partition, you can create a new partition.

Create ZFS Partition

Using gdisk (recommended for GPT disks):

sudo gdisk /dev/nvme0n1

Commands:

1. p - Print partition table (verify current layout)
2. n - New partition
   • Partition number: 4 (or next available)
   • First sector: (press Enter for default - starts after last partition)
   • Last sector: (press Enter for default - uses remaining space)
   • Hex code: bf00 (Solaris root - recognized by ZFS)
3. p - Verify new partition
4. w - Write changes and exit

Alternative: Using fdisk

sudo fdisk /dev/nvme0n1

Commands:

1. p - Print partition table
2. n - New partition
   • Partition type: primary
   • Partition number: 4
   • First sector: (default)
   • Last sector: (default)
3. t - Change partition type
   • Partition: 4
   • Type: bf (Solaris root)
4. w - Write and exit

Verify Partitions

After partitioning:

lsblk

Expected output:

NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
nvme0n1     259:0    0   1.8T  0 disk
├─nvme0n1p1 259:1    0   512M  0 part /boot/efi
├─nvme0n1p2 259:2    0     1G  0 part /boot
├─nvme0n1p3 259:3    0   500G  0 part /
└─nvme0n1p4 259:4    0     1T  0 part
nvme1n1     259:5    0   3.6T  0 disk

Verify partition IDs are available:

ls -la /dev/disk/by-id/ | grep nvme

Look for entries like:

• nvme-<model>-part4 - The new ZFS partition
• nvme-<model> - The secondary disk (whole disk)

Important Notes

Backup First

Always backup important data before modifying partition tables.

Live System

If modifying the boot disk on a running system, consider booting from a live USB. Some partition changes require a reboot to take effect.

Secondary Disk

The 4TB secondary NVMe needs no partitioning - ZFS will use the entire disk.

Next Steps

Proceed to Pool Creation to create the ZFS pool from these devices.