Disk Utility

With the release of Mac OS X 10.11 ("El Capitan"), Apple redesigned the trusty Disk Utility to make it bright and colorful and, in the sad tradition of Apple's "simplification" of iWork, iPhoto and other apps, much less useful.

It has lost the ability to verify or repair file permissions. It can no longer resize disk partitions. There's nothing in the app at all about RAIDs. Apparently, some or all of these feature roll-backs are described as coming features, but that will be too late for people who want to do those things now.

Some enterprising folks have realized that if you can obtain a copy of your old Disk Utility and are not afraid of using the console and doing a bit of hex editing on the old copy, you can run the pre-nerfed version under 10.11.

Instructions: https://justus.berlin/2015/10/restore-old-disk-utility-in-os-x-el-capitan/

Disclaimer: running an old version of a tool as powerful as Disk Utility against a newer version of the operating system is not recommended or supported. By following the instructions in the article, you are definitely "coloring outside the lines." You have been warned.