Bringing your own OS image to a server

Why the standard catalogue sometimes isn't enough

A provider's OS catalogue, the list of Linux distributions and Windows editions offered at order or reinstall time, covers the versions and distributions most customers actually want, and for most workloads that's genuinely enough. See Choosing an OS for your dedicated server or VPS for how to pick from that kind of list. But a catalogue is necessarily a fixed set, and there are recurring reasons it doesn't cover every case:

• A specific minor version pinned by an application's compatibility requirements, rather than whatever the catalogue currently offers as "latest".
• A hardened or pre-configured baseline image, built once internally to a specific security or compliance standard, that needs to be deployed consistently across many servers.
• A distribution or OS the standard catalogue simply doesn't include at all.

In any of these cases, the general answer across the hosting industry is some form of bring-your-own-image support, letting you supply the operating system yourself instead of picking from what's listed.

Path one: upload a custom ISO and install manually

An ISO is a disk image of an installer, the same kind of file you'd burn to a USB stick or DVD to install an OS on physical hardware in front of you. Uploading a custom ISO and booting the server from it, often via a remote console, puts you through the same manual installation process you'd get on hardware in front of you: partitioning, package selection, and any configuration the installer asks for, all done by hand for that one server.

This path gives you full control, you're not constrained by what a pre-built template assumes about the OS, and it works for genuinely unusual or unsupported distributions since you're relying on the installer itself rather than any provider tooling. The cost is manual effort: every installation is a fresh walk through the installer, there's more room for a misconfiguration to slip in unnoticed, and repeating it across many servers means repeating the manual work each time, unless you separately script or automate the installer's own unattended-install mechanism.

Path two: upload a pre-built custom image

The alternative is building the OS image once, outside the provider's environment, disk partitioning, packages, and any hardening or configuration already baked in, and uploading that finished image directly rather than an installer. Deploying from it is then much closer to deploying from a standard catalogue template: the image is written to disk and the server boots straight into a working, pre-configured OS, with no installer to walk through per server.

This path is faster to deploy repeatedly, useful if you're standing up many servers from the same known-good baseline, since the manual effort was already spent once when the image was built. The trade-off moves earlier in the process: getting that image correct and reliably bootable in the first place, matching the target virtualisation or hardware environment's expectations for disk format, drivers, and boot configuration, takes real upfront work, and a mistake baked into the image gets repeated on every server deployed from it.

On Worldstream servers

Worldstream's Create VPS flow in Portal includes an Install Method choice at setup time, between From Template and From ISO: a template-based path using the standard image catalogue, and an ISO-based path for a more manual install. For anything more specific, such as uploading a pre-built custom image directly, supported formats and sizes, or the equivalent on Dedicated Servers, check the current Create flow in Portal or contact support.