How to Spec Enough RAM in Your Lion Server Hardware
RAM is important for speed in the Mac OS X operating system, and this is particularly true for servers. Server applications can often run faster when you add RAM. More RAM also increases the number of simultaneous client connections that the server can handle without bogging down.
For some of the lightweight tasks or if you have a smaller network, 4GB of RAM may be sufficient. If you’re using a Mac mini or iMac on larger networks or with multiple services, add as much RAM as the machine will hold, which can be up to 16GB, depending on the model and age.
This strategy isn’t always practical with the Mac Pro and Xserve because filling them to the maximum can run into hundreds or thousands of dollars — a lot of money if you don’t need the RAM.
On the spare side, it’s possible to achieve acceptable results with 2GB of RAM serving up to 200 users for light, occasional uses. A server with 2GB of RAM may be adequate for a small network of fewer than ten computers for file sharing.
If you’ve been running the server in normal use for a few hours, you can use Activity Monitor (in the server’s Utility folder) to tell whether you have enough memory. At the bottom of the window, click the System Memory tab. Look at the Page Ins and Page Outs numbers.
If the size of the page outs is more than 5 to 10 percent of the page ins, the operating system has to write information from RAM to disk because it doesn’t have enough RAM. This translates into slower server performance. In this case, add RAM to increase performance.
If you do need a lot of RAM, it’s cheaper to buy extra RAM and install it yourself rather than buy it from Apple when you order a new Mac. The price difference is under $100 for Mac mini but can be several hundreds of dollars for Mac Pro.
To find the best prices, check out Ramseeker which lets you compare prices from multiple vendors — like Orbitz does with airline tickets. Just select your Mac model from a pop-up menu, and Ramseeker gives you a list of vendors and prices.