Once you’ve configured the command, press Return to launch it. You can also change the “Ram Disk” name inside the double quotes to another name you prefer. Input this number in place of the X characters in the command above: diskutil erasevolume HFS+ 'RAM Disk' `hdiutil attach -nomount ram://8388608` In our example, we’ll create a 4 GB RAM Disk, which requires a number of 8388608 (4096 * 2048). Calculate this number by multiplying your desired size of disk in megabytes by 2048. Replace the X characters with a number that represents the block size for the total capacity of your RAM Disk. Open the Terminal app from Applications > Utilities and enter the following command: diskutil erasevolume HFS+ 'RAM Disk' `hdiutil attach -nomount ram://XXXXX` In OS X, there are two primary methods of creating a RAM Disk: the Terminal or an app. Now, it’s time to create the Disk itself. Play around with the tools and techniques below to determine the best choice for your Mac and your needs. On the other hand, if you’re just muxing video and audio files you can choose a RAM Disk a bit higher than 50 percent of your total memory.

If you’re doing heavy Photoshop work, for example, you’ll want to leave more memory available for the app. Your choice will also depend on what applications you need to run while the RAM Disk is mounted. On a Mac with 16 GB of RAM, for example, don’t make your RAM Disk bigger than 8 GB. In general, it’s wise to keep your RAM Disk at or below 50 percent of your total physical memory. Therefore, make sure to choose a good ratio between your needs and your overall system memory. You’ll want to be careful to leave enough RAM available to run your Mac, however if you use most or all of your RAM for a RAM Disk, the system will begin paging aggressively to the hard drive and overall system performance will plummet. The methods for creating RAM Disks, outlined below, will allow you to create a volume of any size. If you’ve got good backups of your data and you’re willing to risk losing the contents of a RAM Disk in the event of a power failure, setting one up is easy and fun. But there’s also a major negative: data stored in RAM is not persistent, meaning that it is erased when the RAM loses power due to a reboot, shutdown, or power loss.ĭespite this drawback, there are still several situations that can greatly benefit from the speed of a RAM Disk, including using it as a Photoshop scratch area, manipulating large video files, or testing complicated databases. The benefits are easy to understand: RAM operates at speeds far beyond current hard drive technology. RAM Disks, as the name indicates, are logical storage volumes created using a computer’s memory (RAM) instead of a traditional hard drive or solid state drive. How to Create a 4GB/s RAM Disk in Mac OS X

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