We had heard news about iPhone 6 and iPhone 6 plus issues ever since it has been released earlier this year. For unknown reasons, the handsets would just freeze up on their owners, or even worse, enter a boot loop. After checking on the issue thoroughly, it was found out that the culprit is might be TLC NAND flash memory.
TLC NAND flash is a solid state type of NAND flash memory that stores three bits of data per cell. It can store three times as much data as single-level cell (SLC) that stores one bit of data and 1.5 times as much as multi-level cell (MLC). MLC is a solid state flash memory that stores two bits of data. This makes TLC flash more affordable. However, TLC is also slower than SLC or MLC in reading and writing data.
Apparently, Apple has decided to stop using the TLC NAND and replacing it with MLC NAND. MLC NAND is used in 16GB version of iPhone 6 and iPhone 6 Plus and some 64GB models but the LC NAND was used in all of the 128GB models. TLC NAND was used apparently to reduce costs. To our surprise, some iPads previously is also using TLC NAND.
As the complaints from iPhone 6 and iPhone 6 plus is increasing, some users posts in online communities on possible requests to replace the product due to slow speeds. Therefore, it is getting popular among user to find out whether their device is using MLC and TLC NAND through speed measurement. There is also speculation to a potential recall of iPhone 6 plus since there is technical defects which mainly occur in 128GB version of iPhone 6 Plus as there might be issue in triple-level cell (TLC) NAND flash.