This new disk image format is claimed to be “efficient and general-purpose”. But is it? Is it as fast as sparse bundles or read-write (UDRW) disk images are?
disk image
ASIF disk images are new in Tahoe, and promise to be space efficient, as they’re sparse files, and almost as fast as the disk they’re stored on. Ideal for VMs and general use.
Read-write and VM disk images are created and maintained differently, but they can both be APFS sparse files. Explanation of their creation and maintenance.
How read-write disk images and those used in Apple silicon virtual machines use sparse file format to save space on disk.
From their use to replicate floppy disks in manufacture, to their key roles in macOS, for distribution of software, and on network servers to contain backups. Unglamorous but essential.
Why does compressing a 15 GB file within a sparse bundle run more slowly than would be expected from its write performance?
Why pay an extra $600 for a 2 TB internal SSD, after all fast external SSDs are cheaper. Maybe you need to check whether disk performance becomes a rate-limiting factor.
How do sparse bundles and read-write disk images compare with regard to their efficient use of disk space, and in maintenance requirements? Here are test results from Sequoia.
Sparse bundles (UDSB), read-write disk images (UDRW) and sparse images (UDSP) compared on two SSD, with and without container encryption.
The only disk images of varying size used to be sparse bundles and sparse disk images. Now plain read-write disk images can also vary in the disk space they take, as explained here.
The Eclectic Light Company 