CentOS is gone: what moving 300 servers to RHEL, Rocky or Ubuntu costs

The rebuild is over and the bill is now a decision

CentOS is gone, and the 300 servers that ran on it have to land somewhere. The three destinations a buyer actually shortlists are Red Hat Enterprise Linux, Rocky Linux and Ubuntu, and they differ less in what the kernel does than in who signs the support contract and what that signature costs per host.

Red Hat describes RHEL as an enterprise Linux operating system certified on hundreds of clouds and with thousands of Red Hat partners, sold as a subscription that gives access to all supported versions including the latest release and to the partner ecosystem. That is the paid path: a per-server subscription, quoted rather than listed, wrapped around a distribution Red Hat controls.

Rocky Linux takes the opposite position on the same code. The project states that it rebuilds sources directly from RHEL, that it is designed to be 100% bug-for-bug compatible with Red Hat Enterprise Linux, and that it provides a 10-year support lifecycle at no cost, supported by the community, sponsors and partners. The distribution is free; the support is whoever you can reach.

Ubuntu is the third shortlist entry and the one the supplied pages say least about, so treat its numbers as unpublished here and ask Canonical for the per-host subscription and support terms before you put it in the budget.

What 300 servers actually costs to move

The migration cost is engineer hours per host plus the subscription tier, and the two are not the same size. Rebuilding a host means inventorying what runs on it, replacing packages that came from third-party repositories, retesting the workload and cutting over, and that work is per server whether the destination is free or paid.

At 300 hosts the labour line dominates any single-server subscription, because the same rebuild happens three times over if you split the estate. The subscription line only becomes the deciding number when the host count is high enough that the per-server price multiplied by the term exceeds the engineer hours you would otherwise spend supporting a free rebuild yourself.

Red Hat publishes no per-server price on the page supplied, so the RHEL figure is quote-only. Ask for the list price per host or per socket, the term, what the subscription includes beyond the bits, and whether the price changes at renewal, because those four answers are what the 300-host multiplication needs.

Rocky Linux publishes its number plainly: no cost, 10-year lifecycle. What it does not publish is a commercial support contract, because the project is community supported, so the cost that replaces the subscription is the internal on-call rota or a third-party support agreement you negotiate separately.

Where each destination breaks under 300 hosts

RHEL breaks on budget approval, not on technology. A subscription per server across 300 hosts is a recurring line that procurement has to defend every renewal, and the justification is the certified hardware and software matrix plus the partner ecosystem rather than any capability the free rebuild lacks.

Rocky Linux breaks on the support boundary. The project is explicit that it is community supported, with the community, sponsors and partners investing long-term commitments, and that is a real commitment but not a vendor on the phone at 3am with a contractual response time. An estate with a regulated uptime obligation has to price that gap.

Both RHEL and Rocky carry the same 10-year lifecycle shape, which matters for a 300-host estate because it sets the next forced migration date. Red Hat states it has standardised on three predictable product phases since its eighth release, and Rocky states a 10-year support lifecycle, so the planning horizon is comparable even where the price is not.

The migration itself has a published shortcut on one side: Rocky Linux provides an easy-to-use migration script, free of charge, for moving from other Enterprise Linux distributions. That script reduces hours per host but does not remove the testing, and it is the single line item most likely to make Rocky cheaper than a rebuild on labour as well as licence.

Settings that change the result

The table below holds the criteria the CentOS end-of-life moved: what you pay, who supports it, how long it lasts and what the migration path looks like. Every cell is a fact from the vendor or project pages, and the empty-looking ones are where a number is genuinely unpublished.

Read the price model row first, because it decides whether the 300-host estate is a capital conversation or an operating one. Then read the support row, because that is where the free option stops being free.

The lifecycle row is the one buyers skip and regret, since it sets the date of the next migration before this one has finished.

The number that decides it is the host count

There is a host count where the paid distribution becomes cheaper than the rebuild, and it is the count where the engineer hours you would spend supporting a free estate exceed the subscription multiplied by the term. Below it, Rocky wins on total cost because the licence line is zero and the script cuts the migration hours. Above it, RHEL wins because the subscription buys back the on-call hours the community model leaves with you.

That crossover cannot be calculated from the supplied pages alone, because Red Hat publishes no per-server price there. The arithmetic needs the quoted subscription per host, the term, and your own loaded engineer hour rate, and the answer changes with every renewal.

What the pages do settle is the direction of the trade. Rocky Linux gives you the same source, a 10-year lifecycle and a free migration script at no cost, and asks you to accept community support. Red Hat gives you the certified matrix and a vendor contract, and asks you to pay per server for as long as you run it.

The decision rule for 300 servers

Choose Red Hat Enterprise Linux if the estate carries a contractual uptime obligation that needs a vendor on the phone with a response time, and if the quoted per-host subscription multiplied by the term is smaller than the loaded cost of the on-call hours you would otherwise carry across 300 hosts.

Choose Rocky Linux if the workloads are standard and the team can absorb the support boundary, because the rebuild is free, the migration script is free and the 10-year lifecycle matches the paid option without a renewal conversation.

Wait on Ubuntu until Canonical gives you the per-host subscription, the support terms and the lifecycle in writing, since the supplied pages carry none of those numbers and a 300-host commitment is not the place to estimate them.

Ask Red Hat for the list price per host or per socket and the renewal terms before the first host moves, because that single unpublished number is what turns this from a technical migration into a budget decision.