New disc image format for MacOS 15 and 26 creates the turbo

Practical detail in the upcoming new MAC operating system MacOS 26 alias Tahoe: Apple has screwed on its encrypted disc images. Like IT blogger and Mac & i author Howard Oakley has noticedthe MAC operating system receives a new format that should be significantly more performing than the previous Sparse image format. According to the documentation that is now available, almost native speeds are possible. This makes encrypted disk images significantly more suitable for everyday use.

Create only with Taoe

With a disk image, it is possible to create an entire drive on an external or internal medium, which can be mounted and then used as if it were, for example, a “right” SSD. Apple’s standard format for a encrypted Sparse image, however, only packs around 100 MByte per second, even if the SSD on which it is located is significantly faster. The new format is called Asif. It seems to have been developed in connection with improvements in virtualization and a new container function for MacOS.

At the moment it is only possible under MacOS 26 to write Asif-Disk images. This is done either in the terminal via the command diskutil Or via the hard disk. MacOS 15 alias Sequoia cannot generate any ASIF-DISK images in the latest version 15.5, also hdiutil is not running yet. Mounting and reading/writing on Asifs seems to be possible in Sequoia. It remains to be seen whether Apple is creating a creation with MacOS 15.6, it may be an exclusive feature of MacOS 26.

Bye-bye Sparse-Bundles?

Before that, there had always been the recommendation to use so-called Sparse-Bundles instead of Sparsse-Images, since they were always more performing. This could change with ASIF now, Oakley speculates. This also has various advantages, for example that images is an overall file. Disk images should gradually switch to Asif with Tahoe. The tool Dropdmgwhich makes it easier to deal with, will soon be equipped.

The new operating system will probably appear in September. If you want to try ASIF, you still have to use the Developer Beta of MacOS 26. A public beta appears in July.