When setting up a new Mac, one of the first decisions you need to make is where to install the macOS operating system. You have two main options: install macOS on the Macintosh HD drive, or install it on a separate data drive. The choice comes down to factors like storage capacity, performance, security, backups, and ease of reinstallation. This article will examine the pros and cons of installing macOS on Macintosh HD versus a data drive, to help you make the right decision for your needs.
Macintosh HD Overview
Macintosh HD is the name given to the default disk partition on a Mac computer where the macOS operating system is installed. It serves as the startup disk and system disk that contains all the files necessary to boot up the Mac and run the operating system. The “HD” stands for “hard drive”, which refers to any internal disk storage device whether it is a traditional hard disk drive (HDD) or solid state drive (SSD). Though nowadays Macintosh HD is typically an SSD, the name derives from older Macs that used HDDs.
According to Apple discussions, Macintosh HD holds the macOS system files, applications, user accounts, folders, and documents. It is the main partition and startup disk where the Mac looks first to load the operating system. Without Macintosh HD, the Mac would not be able to start up and function properly. It is essentially the primary system disk required for macOS to operate.
Data Overview
The Macintosh HD – Data drive is a separate volume from the Macintosh HD system drive where macOS is installed. It is specifically used to store user files and data such as documents, photos, videos, music, downloads, and other personal content (Source).
Macintosh HD – Data provides a dedicated location for users to store their files without taking up space on the system drive. It enables users to access and manage their personal data directly. The Macintosh HD system drive contains the operating system, applications, and supporting system files, while Macintosh HD – Data houses all user files (Source).
Keeping user files separate from system files improves performance and organization. It also makes it easier to reinstall macOS or upgrade to a new Mac, since user data remains untouched on the Data drive.
Storage Capacity Factors
How much storage space you need for the macOS system files versus user files and applications depends on the macOS version and your usage. According to Apple, macOS Big Sur requires at least 35.5GB of available storage for installation [1]. However, the actual disk space used by Big Sur after installation is around 15GB [2]. Older versions of macOS like Mojave and Catalina require less space.
The system files for macOS itself don’t take up that much capacity compared to the apps and user files on the computer. For example, if you install many large applications like Microsoft Office, Adobe Creative Cloud, video games, etc., they will quickly consume more storage. It’s also easy to fill up space with photos, videos, music, and other personal files. So make sure to budget extra capacity for your user storage needs.
In general, use the internal drive mainly for the OS, apps, and some core user files. Use external drives for bulk storage of user media, archives, backups, etc. For most users, investing in an external drive allows you to get away with less internal drive capacity for your Mac.
Performance Factors
There are some key performance differences to consider when deciding whether to install macOS on your Macintosh HD or a separate data drive. The OS drive will generally have faster read/write speeds which can impact overall system performance.
According to tests using the Blackmagic Disk Speed Test app [1], the average read/write speeds for Macintosh HD (an internal SSD) are around 2,800 MB/s read and 2,600 MB/s write. In comparison, external Thunderbolt 3 NVMe SSDs connected via 40gbps typically get read/write speeds of around 2,700/1,400 MB/s [2].
Having macOS installed on the faster internal drive can result in better performance for system tasks, app launches, and overall responsiveness. High disk throughput is important for core OS functions. Though modern external SSDs are fast, the internal drive still has advantages.
Security and Reliability
Installing macOS and user data on separate drives can improve security and reliability in a few ways:
First, it allows you to encrypt only the drive containing personal data, while leaving the operating system unencrypted. This protects your files without impacting system performance or boot time [1]. The Mac’s Startup Security Utility can also be used to require a password for certain actions if desired [2].
Second, separating the OS and data physically isolates them. If one drive fails, the other may remain bootable allowing data recovery. And if the OS becomes corrupted, a clean reinstall won’t touch the user data drive.
Finally, installing macOS on the internal drive ensures maximum performance for system files and applications. Data files can reside on an external drive without slowing down the OS [3].
Overall, partitioning into distinct OS and data volumes provides more flexibility for protecting sensitive user files without compromising system security or performance.
Ease of Backup
When deciding where to install macOS, it’s important to consider how easy it will be to back up the drive. The macOS system files and applications take up significant storage space, so backing up the entire OS drive requires having enough capacity to duplicate all of that data.
Time Machine, Apple’s built-in backup solution, makes it easy to back up your entire Mac, including the OS, with an external hard drive or network storage location. However, this may require a high capacity drive if installing macOS on the internal drive, rather than a separate data drive.
Backing up just your user data and settings on a separate drive from the OS can allow for more flexibility. You can use Time Machine or other backup software to selectively backup your important personal files, documents, photos, etc. This prevents duplication of the large OS files and requires less backup drive space.
Overall, installing macOS on a separate drive from your data makes targeted backups of your user files quicker and more storage efficient. But backing up the entire OS drive is also seamless with Time Machine if you have sufficient backup disk space.
Ease of Reinstallation
Reinstalling the macOS on separate drives versus a combined drive like a Fusion drive does come with some key differences. According to Apple Support, reinstalling the macOS on a Fusion Drive requires booting into Recovery mode and choosing the Reinstall macOS option [1]. This will reinstall the OS on the Fusion Drive as a whole.
For separate drives, the process involves erasing and reformatting the drive you want to install the OS on, then reinstalling macOS from Recovery [2]. The key advantage of separate drives is that you can erase and reinstall the OS drive without affecting the data drive. With a Fusion Drive, erasing and reinstalling will wipe both drives.
Overall, reinstalling the OS is simpler on a single combined Fusion Drive, but separate drives allow more flexibility to preserve data when reinstalling macOS.
Recommendations
For most Mac users, installing macOS on the main Macintosh HD drive is recommended for optimal performance and simplicity. Here’s a summary of the recommendations:
Install macOS on the Macintosh HD drive, not a separate data partition, for better performance. Having the operating system and applications on the faster internal drive improves speed and responsiveness (Source).
Don’t partition unnecessarily, as it reduces the total storage space available to macOS and doesn’t provide significant benefits for most users. The exceptions are power users with specific needs for partitions (Source).
Stick with the simpler single Macintosh HD volume approach, which is easier to manage and troubleshoot. Separate data and backup partitions introduce complexity without much upside for casual users.
Leverage macOS’s Time Machine for backup instead of a separate partition. Time Machine makes automated backups seamless and doesn’t reduce available storage space.
For advanced users who want to install Windows or manage multiple operating systems, partitioning can be beneficial. But for most Mac owners, a single macOS install on Macintosh HD is recommended.
Conclusion
When deciding where to install macOS on your Mac, the choice between Macintosh HD and a separate data drive comes down to your specific needs and priorities. Macintosh HD keeps everything neatly together in one place, while a data drive allows you to separate your system files from your personal data. The ideal option provides enough storage, maintains good performance, enables easy backups and reinstalls, and heightens security.
For most users, installing macOS on the built-in Macintosh HD drive is the simpler and more convenient choice. It avoids splitting programs and files across multiple volumes. Performance is snappier when apps and system files reside on the same fast internal drive. Backups and reinstallation also stay straightforward with a single startup drive. Just be sure to leave adequate free space for your needs.
For power users with demanding storage needs or strict security requirements, a separate data drive can make sense. You can devote Macintosh HD solely to system files while storing your personal data elsewhere. This compartmentalizes any malware or corruption. It also enables installing macOS fresh without touching your data. Maintaining this split system does require more monitoring and manual file management, however.
In the end, evaluate your personal workflow, storage requirements, and security priorities. For most Mac users, sticking with the standard single startup drive approach tends to be the simplest and most prudent option.