macOS⁣ TahoeS ASIF Disk Image Format Speeds Up Mac Performance

Updated June 16, 2025

Apple’s macOS 26 Tahoe brings a⁤ new disk ‍image‍ format, ASIF, poised to revolutionize virtual storage handling on Apple silicon Macs. The ‍new ASIF⁣ disk image promises to change that.

Disk images have long been essential for Mac users,facilitating⁤ encrypted file storage and ⁣virtual machine management. ⁤However, performance has ⁤been⁤ a persistent⁢ issue, especially with encryption. Customary encrypted sparse images frequently‍ enough exhibited speeds comparable to ⁢older hard⁢ drives, even on⁤ fast SSDs.

Early ⁢testing indicates ⁢that ASIF images can achieve ⁢read and write speeds nearing a Mac’s internal SSD capabilities. A 100 GB⁢ ASIF image⁣ on a MacBook Pro M3 Pro achieved unencrypted APFS transfer rates of 5.8 GB/s for reading and 6.6 GB/s for writing. ‍With encryption, speeds only decreased to 4.8 GB/s and 4.6 GB/s, respectively. Similar results were seen on a Mac mini ⁤M4 Pro running macOS 15.5,with write ⁣speeds reaching 8.3 GB/s.The ASIF ⁣disk image format represents a notable leap.

Apple⁣ has revealed limited details about ASIF’s mechanics, but the format is designed⁤ to be self-reliant of the host ⁣file system. ASIF images are marked as ‍sparse files in APFS, growing in physical size ⁤only⁣ as data is added. A new 100 GB ASIF image ⁢might initially use less than 1 GB of disk space. Even after substantial use, ‍the image’s footprint typically remains under 3.2 GB when ⁣emptied.

Currently, ASIF disk ⁣images are created using the⁢ Disk Utility app or the diskutil⁤ command-line tool in macOS 26. While straightforward for command-line users,⁤ support is‍ absent in earlier macOS versions and the hdiutil⁢ tool. apple has not specified which older macOS versions will support mounting and ⁤using ASIF images, ⁣raising compatibility concerns.

The performance gains from ASIF are particularly beneficial for virtualization. Apple recommends virtual machines transition from older RAW‍ disk images to ASIF, citing improved speed and efficiency in transferring ⁢VM files. Unlike sparse bundles, ASIF images consolidate all data into a ⁢single⁢ file, simplifying management and⁤ boosting speed.

Despite these advantages, ASIF creation is currently limited ⁤to‍ macOS Tahoe and‍ relies on ‍command-line⁢ tools, lacking a dedicated⁤ API. Third-party apps and virtualizers will need ‍updates to fully⁢ leverage ASIF’s potential. Developers ⁣are already exploring the ‍possibilities, with tools like C-Command’s DropDMG expected to add ASIF compatibility soon.

What’s next

The Mac community awaits broader support and ⁤more technical details from Apple regarding the new‍ ASIF disk image format. The improved disk image performance promises benefits ⁢for users and developers alike.