Comment by kbenson
3 years ago
One server is for a hobby, not a business. Maybe that's fine, but keep that in mind. Backups at that level are something that keeps you from losing all data, not something that keeps you running and gets you up in any acceptable timeframe for most businesses.
That doesn't mean you need to use the cloud, it just means one big piece of hardware with all its single points of failure is often not enough. Two servers gets you so much more than one. You can make one a hot spare, or actually split services between them and have each be ready to take over for specific services for the other, greatly including your burst handling capability and giving you time to put more resources in place to keep n+1 redundancy going if you're using more than half of a server's resources.
Let's Encrypt's database server [1] would beg to differ. For businesses at certain scale two servers are really an overkill.
[1] https://letsencrypt.org/2021/01/21/next-gen-database-servers...
Do they actually say they don't have a slave to that database ready to take over? I seriously doubt Let's Encrypt has no spare.
Note I didn't say you shouldn't run one service (as in daemon) or set of services from one box, just that one box is not enough and you need that spare.
It Let's Encrypt actually has no spare for their database server and they're one hardware failure away from being down for what may be a large chunk of time (I highly doubt it), then I wouldn't want to use them even if free. Thankfully, I doubt your interpretation of what that article is saying.
You're right, from the article:
> The new AMD EPYC CPUs sit at about 25%. You can see in this graph where we promoted the new database server from replica (read-only) to primary (read/write) on September 15.
That says they use a single database, as in a logical MySQL database. I don't see any claim that they use a single server. In fact, the title of the article you've linked suggests they use multiple.
https://letsencrypt.status.io/ shows a list of their servers, which look to be spread across three data centers (one "public", two "high availability").
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This is exactly the OPs recommended solution:
> One Server (Plus a Backup) is Usually Plenty
The I guess my first sentence is about eqally as click-baity as the article title. ;)