1TB and 2TB iPhone 18 Pro and Pro Max use slow QLC memory

Homolab tests show the 256GB and 512GB iPhone 18 Pro models use fast TLC flash, while the 1TB and 2TB versions use QLC. Once caches fill up, sustained write speeds drop to 79.4MB/s, and at 60% storage used to just 1.1MB/s.

• 256GB and 512GB use TLC, 1TB and 2TB use QLC flash
• SLC cache hits 3,000MB/s, QLC manages 79.4MB/s with dips to 25.6MB/s
• At 60% storage used the SLC cache shrinks to 58GB and QLC falls to 1.1MB/s
• QLC model is 38% slower in 4K random reads at low queue depths