Fusion Drive & Swap files

Launch the Activity Monitor application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad. Click Utilities, then Activity Monitor in the icon grid.

Select the System Memory tab. What values are shown in the bottom part of the window for Page outs and Swap used?

Have you rebooted since you got the last warning? If you have, check again the next time it happens.

Your problem is excessive swapping of data between physical memory and virtual memory.

That can happen for two reasons:

• You have a long-running process with a memory leak (i.e., a bug), or
• You don't have enough memory installed for your usage pattern.

Tracking down a memory leak can be difficult, and it may come down to a process of elimination. In Activity Monitor, select All Processes from the menu in the toolbar, if not already selected. Click the heading of the Real Mem column in the process table twice to sort the table with the highest value at the top. If you don't see that column, select

View ▹ Columns ▹ Real Memory

from the menu bar.

If one process (excluding "kernel_task") is using much more memory than all the others, that could be an indication of a leak. A better indication would be a process that continually grabs more and more memory over time without ever releasing it.

If you don't have an obvious memory leak, your options are to install more memory (if possible) or to run fewer programs simultaneously.

The next suggestion is only for users familiar with the shell. For a more precise, but potentially misleading, test, run the following command:

sudo leaks -nocontext -nostacks process | grep total

where process is the name of a process you suspect of leaking memory. Almost every process will leak some memory; the question is how much, and especially how much the leak increases with time. I can’t be more specific. See the leaks(1) man page and the Apple developer documentation for details:

Memory Usage Performance Guidelines: About the Virtual Memory System