Optimized Storage in macOS Sierra and later* can save space by storing your content in iCloud and making it available on demand. When storage space is needed, files, photos, movies, email attachments, and other files that you seldom use are stored in iCloud automatically. Each file stays right where you last saved it, and downloads when you open it. Files that you’ve used recently remain on your Mac, along with optimized versions of your photos.
* If you haven't yet upgraded to macOS Sierra or later, learn about other ways to free up storage space.
Find out how much storage is available on your Mac
Jan 12, 2020 It's not clear why Apple decided to hide the user's Library folder, but you have multiple ways to get it back: two Apple provides (depending on the version of OS X you are using) and one in the underlying file system. The method you use depends on whether you want permanent access to the Library folder or only when you need to go there.
Choose Apple menu > About This Mac, then click Storage. This is an overview of available storage space on your Mac, as well as the space used by different categories of files:
Click the Manage button to open the Storage Management window, pictured below. (The Manage button is available only in macOS Sierra or later.)
Manage storage on your Mac
Where is library quicktime folder on mac. The Storage Management window offers recommendations for optimizing your storage. If some recommendations are already turned on, you will see fewer recommendations.
Store in iCloud
Click the Store in iCloud button, then choose from these options:
Storing files in iCloud uses the storage space in your iCloud storage plan. If you reach or exceed your iCloud storage limit, you can either buy more iCloud storage or make more iCloud storage available. iCloud storage starts at 50GB for $0.99 (USD) a month, and you can purchase additional storage directly from your Apple device. Learn more about prices in your region.
Optimize Storage
Click the Optimize button, then choose from these options.
Optimizing storage for movies, TV shows, and email attachments doesn't require iCloud storage space.
Empty Trash Automatically
Empty Trash Automatically permanently deletes files that have been in the Trash for more than 30 days.
Reduce Clutter
Reduce Clutter helps you to identify large files and files you might no longer need. Click the Review Files button, then choose any of the file categories in the sidebar, such as Applications, Documents, Music Creation, or Trash.
You can delete the files in some categories directly from this window. Other categories show the total storage space used by the files in each app. You can then open the app and decide whether to delete files from within it.
Learn how to redownload apps, music, movies, TV shows, and books.
Where to find the settings for each feature
The button for each recommendation in the Storage Management window affects one or more settings in other apps. You can also control those settings directly within each app.
Empty Trash Automatically: From the Finder, choose Finder > Preferences, then click Advanced. Empty Trash Automatically selects “Remove items from the Trash after 30 days.”
Other ways that macOS helps automatically save space
With macOS Sierra or later, your Mac automatically takes these additional steps to save storage space:
How to free up storage space manually
Even without using the Optimized Storage features of Sierra or later, you can take other steps to make more storage space available:
Learn more
Boot ROM
When the power to a Macintosh computer is turned on, the BootROM firmware is activated. BootROM (which is part of the computer’s hardware) has two primary responsibilities: it initializes system hardware and it selects an operating system to run. BootROM has two components to help it carry out these functions:
If multiple installations of OS X are available, BootROM chooses the one that was last selected by the Startup Disk System Preference. The user can override this choice by holding down the Option key while the computer boots, which causes EFI to display a screen for choosing the boot volume.
The Boot Loader
Once BootROM is finished and an OS X partition has been selected, control passes to the boot.efi boot loader. The principal job of this boot loader is to load the kernel environment. As it does this, the boot loader draws the “booting” image on the screen.
If full-disk encryption is enabled, the boot loader is responsible for drawing the login UI and prompting for the user’s password, which needed to access the encrypted disk to boot from it. (This UI is drawn by
loginwindow otherwise.)
In the simplest case, the boot loader can be found in the
/System/Library/CoreServices directory on the root partition, in a file named boot.efi .
Note: Booting from a UFS volume is deprecated as of OS X v10.5.
In order to speed up boot time, the boot loader uses several caches. The contents and location of these caches varies between versions of OS X, but knowing some details about the caching may be helpful when debugging kernel extensions.
After you install or modify a kernel extension, touch the
/System/Library/Extensions directory; the system rebuilds the caches automatically.
Important: You should not depend on the implementation details of the kernel caches in your software.
In OS X v10.7, the boot loader looks for the unified prelinked kernel. This cache contains all kernel extensions that may be needed to boot a Mac with any hardware configuration, with the extensions already linked against the kernel. It is located at
/System/Library/Caches/com.apple.kext.caches/Startup/kernelcache .
In OS X v10.6 and earlier, the boot loader first looks for the prelinked kernel (also called the kernel cache). This cache contains exactly the set of kernel extensions that were needed during the previous system startup, already linked against the kernel. If the prelinked kernel is missing or unusable (for example, because a hardware configuration has changed), the booter looks for the mkext cache, which contains all kernel extensions that may be needed to boot the system. Using the mkext cache is much slower because the linker must be run. On OS X v10.5 and v10.6, these caches are located in
/System/Library/Caches/com.apple.kext.caches/Startup/ ; on previous versions of OS X, it was located at /System/Library/Caches/com.apple.kernelcaches/ .
Where Is Library Caches Com.app.xbs On Mac Os X 7
Finally, if the caches cannot be used, the boot loader searches
/System/Library/Extensions for drivers and other kernel extensions whose OSBundleRequired property is set to a value appropriate to the type of boot (for example, local or network boot). This process is very slow, because the Info.plist file of every kernel extension must be parsed, and then the linker must be run.
For more information on how drivers are loaded, see IOKit Fundamentals, the manual page for
kextcache , and Kernel Extension Programming Topics.
Rooting
Once the kernel and all drivers necessary for booting are loaded, the boot loader starts the kernel’s initialization procedure. At this point, enough drivers are loaded for the kernel to find the root device.
The kernel initializes the Mach and BSD data structures and then initializes the I/O Kit. The I/O Kit links the loaded drivers into the kernel, using the device tree to determine which drivers to link. Once the kernel finds the root device, it roots(*) BSD off of it.
Note: As a terminology aside, the term “boot” was historically reserved for loading a bootstrap loader and kernel off of a disk or partition. In more recent years, the usage has evolved to allow a second meaning: the entire process from initial bootstrap until the OS is generally usable by an end user. In this case, the term is used according to the former meaning.
As used here, the term “root” refers to mounting a partition as the root, or top-level, filesystem. Thus, while the OS boots off of the root partition, the kernel roots the OS off of the partition before executing startup scripts from it.
Boot≠Root is a technology that allows the system to boot from a partition other than the root partition. This is used to boot systems where the root partition is encrypted using full-disk encryption, or where the root partition is located on a device which requires additional drivers (such as a RAID array). Boot≠Root uses a helper partition to store the files needed to boot, such as the kernel cache. For more information on how to set up the property in a filter-scheme driver, see Developing a Filter Scheme in Mass Storage Device Driver Programming Guide.
Copyright © 2002, 2013 Apple Inc. All Rights Reserved. Terms of Use | Privacy Policy | Updated: 2013-08-08
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