Post Syndicated from Peter Cohen original https://www.backblaze.com/blog/apfs-apple-file-system/
APFS, or Apple File System, is one of the biggest changes coming to every new Apple device beginning next year. Backing up your files is our job, so we think a new file system is very interesting. Let’s take a look at APFS to understand what it is and why it’s so important.
File systems are a vital component of any computer or electronic device. The file system tells the computer how to interact with data. Whether it’s a picture you’ve taken on your phone, a Microsoft Word document, or an invisible file the computer needs, the file system accounts for all of that stuff.
File systems may not be the sexiest feature, but the underlying technology is so important that it gets developers interested. Apple revealed plans for APFS at its annual Worldwide Developers Conference in June. APFS thoroughly modernizes the way Apple devices track stored information. APFS also adds some really cool features that we haven’t seen before in other file systems.
APFS makes its debut in macOS 10.12 Sierra, currently in development with a release this fall. APFS is optional for developers to use right now, but Apple expects to make it mandatory to use in the future. Since our Mac client is a native app, we like many Apple developers, are boning up now on APFS and what it means.
What is APFS?
Apple hasn’t defined the P in APFS, but that differentiates it from Apple File Service (AFS), a term used to describe older Apple file and network services.
APFS is designed to scale from the smallest Apple device to the biggest. It will work with watchOS, tvOS, iOS and macOS, spanning the entire Apple product line. It’s designed from the get-go to work well on modern Apple device architectures and offers plenty of scalability going forward.
APFS won’t change how you see files. The Finder, the main way you interact with files on your Mac, won’t undergo any major cosmetic changes because of APFS (at least none Apple has told us about yet). Neither will iOS, which largely abstracts file management. This is under-the-hood stuff that tells the computer where to put and how to work with data.
The first implementation of APFS is available to Apple developers in the beta of macOS Sierra 10.12. That’s in the hands of testers now, with a general release planned for this September. Apple isn’t making APFS mandatory today, so don’t worry about this getting in the way if you plan to upgrade to 10.12 once it’s out. Apple plans to deploy APFS across product lines beginning in 2017.
This should be a pretty smooth transition that will make work for developers working on apps, and it’s certainly keeping Apple engineers burning the midnight oil, but we’re not expecting a lot of disruption on your end of things. Though some behaviors are changing in how files are stored on disk which will have an effect on you. So read on for details.
Why did Apple make APFS?
The current file system Apple uses is HFS+. HFS was introduced in 1985, back when the Mac was still new. That’s right, more than thirty years ago now. (HFS+ came later with some improvements for newer Macs.)
To give you an idea of how “state of the art” has changed since then, consider this. My first Mac, which came out late in 1984, had 512 KB of RAM (four times the original Mac’s memory) and a single floppy drive that could store 400K. This computer I’m writing from now has 8 GB of RAM – almost 16 thousand times more RAM than my first Mac – and 512 GB of storage capacity. That’s more than 1.2 million times the capacity of that early machine. Think about that the next time you get a message that your drive is full!
Given the pace of computer technology and development, it’s a bit startling that we still use anything developed so long ago. But that’s how basic and just how important a file system is to a computer’s operation.
HFS+ was cutting-edge for its time, but it’s designed for computers with floppy disk drives and hard drives. Floppies are long gone. The vast majority of Apple devices now use solid state storage like built-in flash and Solid State Drives (SSDs), and those store data differently than hard drives and floppies did.
Why is APFS better?
APFS is designed from the start to better suit the needs of today’s and tomorrow’s devices. It’s thoroughly optimized for devices that use solid state storage – flash and SSDs. These storage technologies work differently than spinning drives do, so it only makes sense to optimize the file system to take advantage.
Apple’s paving the way to store lots more data with APFS. HFS+ supports 32-bit file IDs, for example, while APFS ups that to 64-bit. That means that today, your Mac can keep track of about 4 billion individual pieces of information on its hard drive. APFS ups that to 9 quintillion. That’s a 9 followed by 18 zeroes (actually, much more than that, because of hexadecimal values).
Even though APFS can keep track of orders of magnitude more data than HFS+, you’ll see much faster performance. When you need to save or duplicate files, APFS shares duplicate data between files whenever possible. Instead of duplicating information like HFS+ does, APFS updates metadata links to the actual stored information. Clones, or copies of files or folders can be created instantly. You won’t have to sit and watch as gigabytes of files are duplicated en masse, wasting egregious amounts of space in the process. In fact, clones take up no additional space, since they’re pointing back to the original data! You’ll get much better bang for your storage buck with APFS than HFS+ can manage.
Speaking of space, Space Sharing is another new feature of APFS. This helps the Mac be more effective at managing the free space on its hard drives. You can set up multiple partitions, even multiple file systems, on a single physical device, and all of them can share the same space. You presently have to jump through hoops if you’re resizing partitions and want to re-use de-allocated space. APFS views individual physical devices as “containers,” with multiple “volumes” inside.
Networking is vitally important for almost all computers and computing devices. Over the years there’s been a lot of emphasis on tuning operating system performance for maximum throughput. That’s helpful to developers like us, because we store data in the cloud. But that’s not the whole story. Latency – the amount of time between you telling your computer to do something and when it actually happens – also has a big effect on performance.
Has “the Beachball of Death” ever plagued you? You’ll click a button or try to open something, and the cursor changes to a spinning disk that looks for all the world like a beachball. Apple’s doing a lot more with APFS to make beachballs go away. That’s because they’re prioritizing latency – the amount of time between when you ask your device to do something and when it actually does it.
Apple has found other ways to improve performance wherever possible. Take crash protection, for example. HFS+ uses journaling as a form of crash protection: It keeps track of changes not yet made to the file system in log files. Unfortunately, journaling creates performance overhead. Those log files are constantly being written to and read from. APFS replaces that with a new copy-on-write metadata scheme that’s much more efficient.
Apple is very concerned with user privacy. Their protection of their users’ privacy has occasionally put Apple at loggerheads with governments and individuals who want information off machines. Apple’s taking your privacy seriously with APFS, thanks to much more sophisticated encryption options than before.
Apple’s FileVault technology is its current encryption scheme. FileVault is what’s known as “whole disk” encryption. You turn it on and your Mac encrypts your hard drive. That encrypted data is, for all intents and purposes, unrecognizable unless you enter a password or key to unlock it.
The problem is that FileVault is either on or off, and it’s on or off for the whole volume. So once you’ve unlocked it, your data is potentially vulnerable. APFS still supports whole disk encryption, but it can also encrypt individual files and metadata, with single or multi-key support. That provides additional security for your most sensitive data.
As a backup company, one feature of APFS we’re particularly interested in is its support of snapshots. Snapshots are a pretty standard feature of enterprise backups, but we haven’t seen them yet on the Mac. A snapshot contains pointers to data stored on your disk, providing fast access to data stored on the disk. Because the snapshot contains pointers, not the actual data, it’s compact, and accessing it is very fast.
There’s a lot more under the hood in APFS, but that gives you a broad overview of what it is and why we’re excited. We hope you are too. We’ll be bringing you more details about APFS, and if you have questions, please let us know.
Over the course of the next few months, we‘ll go behind the scenes of our engineering department to show you the impact and opportunity the change to APFS and other new technologies creates for Backblaze. Since our Mac client is a native app, this promises to be pretty cool. Stay tuned.
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