The release of the updated iMac was marked by the appearance of such an interesting thing as Fusion Drive. This technology is designed to solve the actual problem, which can be described as “I want SSD speed and capacity of HDD and without bread, please”. So what is this technology?
At the level of iron Fusion Drive are two separate disks, one of which is a solid state drive (SSD), and the second disk is a familiar drive on hard magnetic disks (HDD). Apple decided to include in its products a variation of Fusion Drive with an SSD of 128 GB, and variations of HDD capacity of 1 TB and 3 TB. Simply put, all magic Fusion Drive is carried out at the level of the operating system and consists in monitoring the frequency of access to certain applications and data and transfer them in accordance with this frequency on the SSD, or on the HDD drive.
Even easier: the OS and everything-everything-that you often launch, listen and look (browser, for example), will be stored on a fast SSD, and the rest – on the HDD. If you suddenly start to master Photoshop and start to run it daily, then this application, as well as related data (your art), will also be transferred to the SSD.
Fusion Drive is not caching
More precisely, the concept of Fusion Drive does not require that data from the HDD be duplicated on the SSD. SSD here does not act as a place solely for fast processing, inaccessible for data storage. Here the user gets all the useful space from both disks, that is, if you have 128 GB SSD and 1 TB HDD, then you have 1.12 TB of available disk space for data storage.
Fusion Drive is not RAID
As mentioned above, Fusion Drive works at the operating system level. Disk Utility recognizes 2 separate disks, and the OS converts them into a single space.
How to be with backups
Backups should be done as before. Time Machine will back up as if you have one disk. In the event of the death of one of the disks, be it SSD or HDD, the user will have to do a full recovery. However, if there is no backup, then the user will probably be able to extract data from the live disk, at least this is almost 100% likely to be done with additional utilities.
How to be with the replacement
Apple noted that the design of HDD and SSD in their product does not differ from the discs of other manufacturers, so if you burn one of the disks, then you can replace it with a third-party drive.
Recording Features
The big plus from the point of view of speed is that all the written data is initially written on SSD, and we know that on SSD everything is written faster. Naturally, in the future, the OS will determine how often you access the recorded data and decide whether you need to leave them on the SSD SSD, or transfer it to the HDD.
Your questions
There are still a lot of questions about this shuffling of data from SSD and HDD. How correctly can the OS determine which data should be transferred to the HDD, and which ones should be left on the SSD? What will this system give to users who shovel tons of data in transit and at the same time do not store the downloaded information for a long time (downloaded five FullHD movies, watched, took down movies, downloaded, watched, demolished, and so on)? Will the unnecessary hardware and data cycles of writing and reading when shuffling data between disks for the lifetime of the disks themselves (is especially critical for SSD)? How will the background shuffling of data between disks affect system performance at the time of data movement? We hope that Apple took everything into account.
