Solid state drives are awesome . Once you’ve had one, you’ll never want to go back to relying on sluggish hard drive platters and delicate moving parts again. The only snag is that solid state storage is still prohibitively expensive for storing lots of data. While a 256GB or 512GB SSD might be fine for your oft-used apps, OS and local documents; when it comes to terabytes of movies, music and photos an SSD is not a cost effective option.
The days of cheap SSD storage are probably not that far away, but for the moment Apple has come up with an interim solution. By using an SSD and a traditional slow-moving hard drive, the company hopes to strike a balance between space and speed, and the best part is that your Mac will handle all the hard work for you.
Intrigued? Read on to find out how Fusion Drive works.
Fusion What Now?
Fusion Drive is simply the name given technology that uses a solid state drive and a hard disk drive in tandem. The term Fusion Drive doesn’t really mean anything, except when you look at it from a software point of view. Apple’s technology, built into OS X Mountain Lion and later, manages your data using Fusion Drive to best maximise the performance you get out of your Mac.
This means your Fusion Drive appears as a single volume on the disk rather than showing the SSD and HDD as separate volumes. They are combined into a single logical volume, so you don’t need to think about where you put what. In fact, that’s the best part of it – you simply copy to the hard drive, and OS X handles everything for you.
Whenever data is added to your machine – be it a piece of software, a browser download or your iPhone photos – it is copied to the SSD first. Until this SSD starts to fill up considerably (believed to be around 4GB remaining space), your machine will solely rely on the faster solid state storage. Once you’ve filled up this space, then OS X starts its process of managing your data, but it will always keep a small amount of space free as buffer for incoming data. This ensures file transfers, copies and other incoming disk operations remain as fast as the SSD permits. Because of this, write speeds will always remain fast.
The operating system monitors your data habits from the word go, even before you need to start using the space on the slower HDD. When the time comes to move data, the OS will do so based on what it has seen you use most often, and that which you use least of all. The movement of this data between drives is not a one-way operation, and the OS will continue to learn based on your habits, and move things around to match your usage.
Partitions, Boot Camp & Price
If you’re considering installing Windows via Boot Camp or otherwise need to partition your Mac’s drive, Apple claims that Disk Utility will allow you to do this to create one additional volume. You cannot partition the SSD, as this is used by OS X solely. Partitioning will create a separate volume which appears as another drive in your Mac, which is not part of your Fusion Drive and thus won’t be used to migrate data. For this reason, this volume will match the speed of a traditional hard drive and forgoes the benefits the hybrid system provides.
In Mountain Lion 10.8.2, Disk Utility would not work with 3TB partitions which meant that Boot Camp Assistant refused to partition a Windows volume. If you’re using a 3TB Fusion Drive, you’ll need to ensure you’re running Mountain Lion 10.8.3 or later in order to do this by updating your Mac using the Updates tab via the Mac App Store.
At the time of writing, Fusion Drive must be specified as an extra when ordering your iMac or Mac mini on the Apple website. Unfortunately, Fusion Drive technology is not available in Apple’s line of MacBook computers though if you’re using an older MacBook you can still ditch your optical drive in favour of an SSD for speed benefits alone.
For a base-level 21″ iMac or 1TB Mac mini (which already comes with a 1TB SATA hard drive), Fusion Drive adds an additional $250 to the cost. For the base model 27″ iMac, this cost is reduced to an additional $150.
Whether it’s worth it or not depends on whether the additional speed is worth a couple of hundred dollars to you. I’ve been spoiled by my MacBook’s SSD for a whole year now, and I don’t think I could go back to relying on a slow hard disk alone. I also find myself frustrated by a lack of local storage space, and so the idea that a trade-off between space and speed is available for a fee I can stomach seems like an attractive option to me.
I’d say it’s worth it – but would you? Let us know what you think in the comments, below!
Image credits: Samsung SSD (Hong Chang Bum)