Disk Utility hadn’t changed much over the years. The hoary app used for creating logical divisions in disks, applying first aid to ones with data damage, and repairing permissions seemed a thing from a previous age. With El Capitan, Apple has done more than slap on a fresh coat of paint. It has most of the same features, but the interaction and display is entirely different.
Expert users may be frustrated and resort to learning the ins and outs of
diskutil, the command-line utility available via Terminal that’s always had more switches and controls than the graphical Disk Utility.
But for many users who need to make quick and rare trips to this software, it could be an improvement: less frightening, easy to use, and harder to make mistakes.
One bit of terminology calibration before we proceed for those who don’t typically deal with disk settings. It’s typical to call a physical drive—whether a USB thumb drive, an SSD, or a hard drive—a drive. You format a drive to make its raw storage compatible with one or more operating systems. A physical drive has logical divisions, called partitions, that allow different formatting parameters on the same physical drive. Each mountable partition can appear as a separate disk icon in the Finder; these are often called volumes and, via Terminal, can be found in
Before digging into how to use the new setup, it’s important to note a key omission: Verify Permissions and Repair Permissions are gone. The sworn-by advice for years by experienced OS X users and Apple alike was to run Disk Utility and click Repair Permissions as the first step in troubleshooting something gone wrong: a printer driver failing, an app’s strange behavior, a weird interface glitch? Repair permissions!
In OS X (and in all Unix and related OSes), a file or directory’s permissions associate which kind of user can perform what kind of action: read, write, execute (run, like a program), and other attributes. It made sense that repairing permissions on files for which OS X knew precisely what settings should be in place could fix random faults. A printer driver with the wrong switches flipped might not be available to the system; or the driver might be unable to access the printer settings file or temporary print queue directories. Even so, from all reports, permissions repairs had little real effect for years—it just made us feel better.
But in El Capitan, any system file for which Repair Permissions would have restored these settings can no longer be modified during normal operating. System Integrity Protection (SIP), also known as rootless mode, prevents modification to these files.
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