Applies to: Ubuntu Server 26.04.1 LTS and 24.04.5 LTS (installer screens checked against the current Subiquity installer source; disk resize tested on Ubuntu 24.04 with LVM 2.03.16)

To install Ubuntu Server, download the live server ISO, boot the machine from it and follow the text installer. Two defaults catch people out: the OpenSSH server is not installed unless you tick it, and on disks larger than 10 GiB the default LVM layout leaves part of the space unused. Both are covered below.

Before you start

  • Version: Ubuntu 26.04.1 LTS is the current release; 24.04.5 LTS is still supported. According to Canonical, LTS releases get five years of free security updates, extendable to 15 years with Ubuntu Pro.
  • Minimum hardware (Canonical’s download page): 1.5 GB RAM and 5 GB of free disk space.
  • On a VPS you usually don’t need the ISO: reinstall from a ready template in Virtualizor (automatic OS installer), or see manual OS install in Virtualizor.
  • On a dedicated server, mount the ISO as virtual media through IPMI: install an operating system using IPMI.

1. Download and check the ISO

Download ubuntu-26.04.1-live-server-amd64.iso (about 2.9 GB) and the SHA256SUMS file from the same release folder, then check the file:

sha256sum -c SHA256SUMS --ignore-missing            # Linux
shasum -a 256 ubuntu-26.04.1-live-server-amd64.iso    # macOS: compare with SHA256SUMS
certutil -hashfile ubuntu-26.04.1-live-server-amd64.iso SHA256   # Windows

On Linux a good download prints ubuntu-26.04.1-live-server-amd64.iso: OK; a damaged one prints FAILED and WARNING: 1 computed checksum did NOT match.

For a physical PC, write the ISO to a USB stick of 4 GB or more. Canonical’s Windows tutorial uses Rufus.

2. Go through the installer

  1. Language: use the Up, Down and Enter keys.
  2. Keyboard configuration: choose the layout, or use Identify keyboard.
  3. Choose the type of installation: keep Ubuntu Server (the default, with a curated set of packages for running a server). Ubuntu Server (minimized) is meant for machines where people don’t normally log in. Tick Search for third-party drivers only if you need them.
  4. Network configuration: the installer uses DHCP. For a fixed address, select the interface, choose Edit IPv4, set the method to Manual and fill in Subnet (CIDR form, for example 203.0.113.0/24), Address, Gateway and Name servers.
  5. Proxy configuration: leave empty unless your network needs one.
  6. Ubuntu archive mirror configuration: keep the default once it shows This mirror location passed tests.
  7. Guided storage configuration: Use an entire disk, pick the disk, and keep Set up this disk as an LVM group (ticked by default). Encrypt the LVM group with LUKS asks for a passphrase at every boot, which is awkward on a remote server.
  8. Check the summary, select Done, then Continue in Confirm destructive action. Everything on the selected disk is erased.
  9. Profile configuration: Your name, Your server’s name (the hostname), Pick a username, Choose a password. The installer notes that a password is still needed for sudo even if you log in with SSH keys.
  10. Ubuntu Pro: choose Skip for now unless you have a token; you can attach it later.
  11. SSH configuration: tick Install OpenSSH server. It is off by default, and without it you can’t log in remotely. Import SSH key can fetch your public keys from GitHub or Launchpad.
  12. Featured server snaps: leave them unticked and install software later with apt.
  13. When you see Installation complete!, select Reboot Now and remove the USB stick or unmount the virtual media.

3. Give the root volume the whole disk

With LVM, the installer does not always use the full disk for /. In the installer source, the root volume gets all of the available space if it is under 10 GiB, 10 GiB if it is under 20 GiB, half of it if it is under 200 GiB, and at most 100 GiB of anything bigger. The rest stays free in the volume group ubuntu-vg. Check and extend it after the first login:

sudo vgs                      # VFree shows the unused space
sudo lvextend -r -l +100%FREE /dev/ubuntu-vg/ubuntu-lv
df -h /

On our small test volume, lvextend answered:

Size of logical volume ubuntu-vg/ubuntu-lv changed from 1.00 GiB (256 extents) to <3.00 GiB (767 extents).
Logical volume ubuntu-vg/ubuntu-lv successfully resized.
Filesystem at /dev/mapper/ubuntu--vg-ubuntu--lv is mounted on /mnt/root; on-line resizing required

The -r option grows the ext4 file system in the same step, while it is mounted, so no reboot is needed.

4. First steps after installing

Installing on your own hardware? Ucartz unmanaged dedicated servers come with full root access and free IPMI KVM, so you can install Ubuntu from the ISO yourself.

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