Memory: manual mode
A fixed amount of memory, and why MSL warns above three fifths of your Mac's RAM.
The Memory picker on the Processor & memory card has two modes: Manual and Dynamic. This page is about Manual; Dynamic has its own.
Manual is a fixed amount, reserved on your Mac the whole time the instance is running. Type a number of megabytes in the Memory field and click Apply.
| Megabytes | Is |
|---|---|
| 1024 | 1 GB |
| 2048 | 2 GB |
| 4096 | 4 GB |
| 8192 | 8 GB |
If you've never changed it, an instance gets a sixth of your Mac's memory, at least 1 GB and at most 8 GB — enough for desktop apps, and small enough that four instances together can't crowd macOS out.
The warnings#
MSL checks the number as you type and explains anything worrying in a coloured box under it.
Pressing Return in the field also snaps a value that's out of range back to the nearest allowed one.
When it takes effect#
At the instance's next start. A running instance keeps the memory it booted with; a hibernated session is discarded rather than resumed into a differently sized machine.