SQL Server Core Edition

Sorry to necro here, but just in case someone else hits this page with a similar question, and since there's so little documentation about this...

Short: The regular "Enterprise" (non-"core") edition caps the cores at 20, period. The "core" edition has no such cap. This is not a guess, it's a provable certainty. I ran into the specific question "when do I NEED the Core edition, vs. not?" about a year ago.

The good news: an edition upgrade from non-core to core is utterly painless and very fast. As in it takes longer just to get to the Upgrade button in setup, than to actually perform the upgrade when you hit it.

Virtualization side-note: this has nothing to do with cores on the host. Just how many are assigned to the Windows VM. I'm not sure how or why anyone would give a VM more than 20 cores (at that point your host is already a dedicated server most likely), but if so... then yeah, this applies to your guest. If your host has 40 cores but you never assign 20+ to any guest, don't worry about it.

Explanation: The non-core edition, as others stated, is intended for Server/CAL licensing. Even if you're paying for core licensing, and paying for more than 20 cores on a server, it's still capped at 20. Yes - that means you're wasting a LOT of money. Yes, that sucks - so if your boss is itching for a reason to fire you, be sure to point out that yeah... documentation about the "Core-licensing" edition is extremely lacking. Or be sure you have an unloved teammate you can throw under the bus. :). I ran into this the hard way, on a server with 60 cores, running for over a year, and because admittedly I was not paying enough attention... yeah, we were effectively wasting 40 core licenses. I'm lucky though - I have a cool boss, plus three teammates and two lead developers that also had no clue about this, backing me up.

p.s. You can verify this yourself, the same way I finally discovered it, on a server with more than 20 cores of course. Check sys.dm_os_schedulers, in particular the "status" column. Cores in-use show "VISIBLE ONLINE." If you have more than 20 cores, but the non-core edition, you'll see only 40 rows with that status. With the Core edition, you'll see twice as many rows as you have cores. "40" and "twice" are assuming HT is enabled; if not, half those figures. This is also assuming you didn't monkey with processor affinity.

p.p.s. in fairness to the community at large, most DBAs don't ever see a server with more than 20 cores unless they're in a large enterprise environment. Even then, if scale-out strategy is usually "the norm," you'll normally have not-quite-beast-level servers. 20+ cores means you have a seriously loaded database, a budget that doesn't even flinch at buying a server that costs 6 figures, and multiple levels of bosses that are all on the same page. Yeah... not a very common scenario. Doesn't really excuse MS, even their licensing "experts" never bothered to point this out in the course of the past nine years, but at least it explains why not many people seem to "know" about this.