The #1 mistake hosting providers make for MySQL serversBaron Schwartz
This article is not meant to malign hosting providers, but I want to point out something you should be aware of if you’re getting someone else to build and host your servers for you.
Most hosting providers — even the big names — continue to install 32-bit GNU/Linux operating systems on 64-bit hardware. This is a serious mistake.
You have to tell them to install a 64-bit operating system. If you don’t then you will come to a point where your needs grow and you want to use more memory — and they will gladly install 8 or 16GB of memory for you, but MySQL can’t use it because it runs in a single process, which is limited to about 2.5GB of memory. And then you have to rebuild the whole operating system from scratch. But you don’t want any downtime, so you have to buy another server, set it up as a slave, switch your site to use it, and then rebuild the old server. That 32-bit OS turned into a pretty expensive mistake.
I do not know why the hosting providers keep doing this. Just yesterday I got a quote from a hosting provider for a medium-high-end system with 8GB of RAM, and forgot to tell them 64-bit OS, and they actually listed 32-bit explicitly on the quote — useless! I would estimate about half of all the hosted systems I’ve seen so far have this mismatch. I don’t know why they do this — maybe there is a reason, but I don’t know it and it looks pretty silly to me. 64-bit hardware and operating systems aren’t new anymore. In fact, 32-bit is hard to find in server-class hardware these days. So it certainly looks like the hosting companies need to change what they’re doing, but maybe there’s a different reason.