Apple introduces ASIF disk image format in macOS 26 Tahoe for faster virtual storage

What just happened? Apple's latest update for Macs, macOS 26 Tahoe, introduces a significant leap forward in disk image technology with the debut of the ASIF format – a development that could reshape how users and developers handle virtual storage on Apple silicon Macs.

For years, disk images have been a staple for Mac users, enabling everything from encrypted file storage to virtual machine management. However, these images have long suffered from sluggish performance, especially when encryption is involved. Even on Apple's fastest internal SSDs, traditional encrypted sparse images (UDSP) sometimes crawl along at speeds reminiscent of outdated hard drives, rarely exceeding 100 MB/s.

The new ASIF disk image format, now available in macOS 26 Tahoe, promises to change that. Early testing reveals that ASIF images can deliver read and write speeds that approach the raw performance of a Mac's internal SSD – an unprecedented jump for virtual ...