Regardless of the number of storage devices you have attached or built into your Mac, you will likely use Disk Utility for formatting them when necessary, to partition and resize them for various purposes, and otherwise managing them. However, one limitation you might find when using Disk Utility is that it will only act on one drive or volume at a time.
For the most part this is not much of a problem, since operations like a quick format or partitioning of a device can take only a few moments; however, there are times when longer operations on one device can have you waiting around to perform operations on other devices. For instance, if you have a number of drives that you want to securely format or zero-out, it may take hours to format each one. You might also be in the middle of performing a drive wipe, and wish to test another drive you have on hand.
1. Select multiple devices for verification and repair
When performing First Aid routines such as verification or repair on a device, you generally do so on one selected device in Disk Utility’s sidebar; however, you can quickly do this on multiple devices by holding the Command key and then clicking each to add them to a selection. You can then run your verification and repair on the selection, and Disk Utility cycle through each selected disk to perform these actions.
2. Launch multiple instances (or windows) of Disk Utility
For operations where Disk Utility cannot act on a selection of disks, like formatting disks, you can still perform multiple instances of these operations at a time. In Disk Utility, you can press Command-N to open a new window, but another approach you can take is to launch multiple instances of the program. By default, OS X will only open one instance of an application, so double-clicking a program that is already open will switch to it, instead of launching a new process; however, you can run a second instance of a program, if needed.
To do this for Disk Utility, open the Terminal and run the following command for as many separate instances of Disk Utility that you would like to launch:
open -n -a "Disk Utility"
With these instances open (either as a new window, or as separate processes), you can now use one to start a long format process on one of your disks, and use another for a similar process on another disk.
Note that multiple instances of programs should only be done on non document-based programs, that is, programs that do not support files you can save and open in multiple windows (e.g., TextEdit, or Pages). Having multiple instances of the program open will affect services like Apple’s Autosave and Resume, and may overwrite or delete unsaved work you have open in these programs.
3. Use the “diskutil” terminal command
Launching separate Disk Utility processes is similar to opening different Terminal windows and using the “diskutil” command in each to perform actions on separate disks. The specific uses of this command will require you be a little familiar with the Terminal; however, as a general principal you can run the following command to get a list of your disk device IDs, which will be labeled something like disk0, disk1, disk2, etc., or individual partitions by their “slice” identifier, such as disk0s2, or disk1s1, etc.:
Following this, you can perform your desired actions on your drives or slices in separate Terminal windows, and this will have the “diskutil” command operate on your drives all at once, as opposed to having to perform them sequentially in one Terminal window. Note that in most cases, after supplying the diskutil command’s various arguments and options, the last argument is to supply your drive device. You can do this by typing its device identifier, but can also do this by specifying the full path to the root of the device. Since the OS X Terminal supports drag-and-drop for entering file paths, an easy way to run various commands on different drive devices is the following:
- Open a new Terminal window
- Type in your diskutil command and arguments (e.g., “diskutil zeroDisk”) followed by a single space.
- Drag your desired disk from the Finder to the Terminal window to enter its full path as the last command argument.
- Press Enter to run the command.
As this command runs its course, you can repeat this procedure to quickly run another instance of diskutil on another volume and get another formatting process going. As with launching multiple instances of Disk Utility, this can be a quick way to attach a series of devices and format or otherwise manipulate them.