Ubuntu 24.04 LTS To Support Installs With NVMe-Over-TCP Drives
Going back several months Canonical engineers have been working on Ubuntu installer support for NVMe-over-TCP as the extension of the NVMe protocol over TCP/IP networks using standard Ethernet. NVMe/TCP can allow creating large disaggregated NVMe storage pools and more for use within data centers.
With Ubuntu 24.04 LTS will be preliminary support for having the root file-system on a remote drive via NVMe/TCP while the /boot and /boot/efi will need to be housed on local storage.
The code is all now merged with the feature freeze exception having been granted last week for allowing this late feature addition.
"It's still early, and I know that the feature is basically landed already. I'm also quite confident in the testing story of subiquity. Let's get this merged and into images as soon as possible. FFe approved."
That feature freeze exception sums up this new feature work as:
"* Subiquity will offer to install Ubuntu with the rootfs (or another essential mountpoint like /usr) on a remote block device - as long as the /boot (and /boot/efi if needed) are located on a local drive.
* Curtin will deploy an initramfs hook script and boot script that will:
* bring up the network early in the boot stage (note that only trivial network configurations will be supported)
* connect to the remote NVMe drives
* At boot time, the network should automatically be brought up, the connection to the NVMe drives established, and the rootfs should end up automatically mounted.
* The support for NVMe/TCP is still marked experimental in curtin.
Expected impact
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* For 24.04, the ability to discover remote block devices using NVMe/TCP is out of Subiquity's scope. Therefore, the ability to install to NVMe/TCP drives is a feature invisible to 99% of our users. One way to make the feature visible (provided that NVMe/TCP drives are accessible on the network) is to run specific `nvme connect` or `nvme connect-all` commands using the nvme-cli package. This can be done using autoinstall early-commands or by spawning a debug shell in Subiquity.
* The NVMe/TCP work in Subiquity is also a work in progress and is adverted as experimental in curtin. If a regression is introduced when adding the ability to install with / on a remote drive, the users could still play around with the old behavior by changing / to /home."
Ubuntu 24.04 LTS will be out toward the end of April with this and many other new features as Canonical's newest Long Term Support version.
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