If you frequently change your cellphone or are a phone enthusiast, you will notice that the maximum phone storage capacity has drastically increased over the last few years. It started with barely 8GB storage space in the 2000s, and now you can get up to 1TB in the same-sized smartphone.
Like all other gadgets, mobile phone storage technology has come a long way in the past few decades. Like the RAM, the demand for increasing storage space with faster read and write is also at its peak. Alongside this, the image quality from the cameras and the games is also increasing in size, creating a demand for better storage performance.
If you look at the storage specs of any phone today, you will most likely be interested in its capacity. However, one thing that is often overlooked is the type of storage it has. The type determines what technology it uses, and hence, the standards and specifications it has. These things add to the performance of the phone, and hence, the User Experience (UX).
By the end of this guide, you will have understood the different types of storage technologies used in mobile phones, how is one better than the other, and which one you need for your daily tasks.
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What is flash memory?
The flash memory is a non-volatile storage type. This means that it retains the information even when the power is lost, unlike the RAM. The data from a flash memory can be erased electrically. The flash memory is based on the Metal-Oxide-Semiconductor Field-Effect Transistor, or MOSFET – a term only electrical engineers should be familiar with – but the technology which started in 1959 led to the flash memory’s development.
The MOSFET led to the development of the floating gate MOSFET. With the evolution of this technology, EPROM and EEPROM were born – two types of read-only and user-programmable storage technologies, respectively. The EEPROM led to the development of the flash memory in the 1980s.
The flash memory was initially of two types: NAND and NOR. These were both raw flash memory types that performed the same function – retain data with no power.
The NOR flash memory provides access to any location on the memory where a single byte of data can be read or written at any single time. However, a NAND flash memory can be easily erased or reprogrammed in huge blocks that are of thousands of bits. This is the reason the NAND flash memory gained precedence and is why it is the type of flash memory being used in most smartphones.
The NAND flash memory uses electric circuits to store data in blocks. A metal-oxide semiconductor will give the memory cell an additional charge when the power to the NAND flash memory is cut off, preserving the data. A floating-gate transistor (FGT) is the most common type of metal-oxide-semiconductor used.
The NAND flash memory
The NAND flash storage is preferred over NOR storage because of its block erasing and reprogramming support and ability to handle huge amounts of data. Also, you have one or more flash memory chips containing numerous flash cells when it comes to flash memory devices.
Single Level Cell (SLC) technology, included in early NAND flash memory, limited bit storage to one per cell. Over time, two or more bits might be stored in a single cell thanks to the introduction of Multi-Cell Levell (MLC) NAND flash memory. Additionally, Quadruple-Level Cell (QLC) flash memory with four bits per cell and Three Level Cell (TLC) flashes with three bits per cell are available.
Now that you understand what a NAND flash memory is, it is time to discuss the types of phone storage technologies, since they are both types of flash memory.
Embedded MultiMedia Card (eMMC)
The Embedded MultiMedia Card (eMMC) storage, also known as the managed flashed memory, was launched by the MultiMediaCard Association (MMCA) in 2006.
The eMMC storage has a non-removable flash memory controller, unlike a Secure Digital (SD) card. With the interface circuit placed on the circuit board of the smartphone, it is created as a tiny ball grid array. The reliable controller makes sure that the data is written or read without corrupting the rest of it.
MMCA later handed over all rights and technologies to JEDEC in 2008. JEDEC then ensured that the eMMC technology was well-adjusted to the changing requirements of the world, and made eMMC the most used storage technology in smartphones., up until a certain point at least.
JEDEC then further developed the eMMC technology until version 5.1, released in 2015. After that, the other type of flash memory, which was Universal Flash Storage (UFS), had already shown more promising results, and the eMMC technology was abandoned.
Universal Flash Storage (UFS)
The UFS technology has been around since 2011, but initially, it was of lower performance than the eMMC technology and therefore did not make the headlines at the time. However, it has been upgraded quite significantly since then, so much that it has superseded eMMC in every way, and the eMMC has been abandoned by JEDEC in terms of further development.
Similar to eMMC, UFS utilizes a controller and NAND flash memory, but its architecture is completely different. Flash technology has advanced thanks to the introduction of NAND technology. This gets us to V-NAND or 3D NAND – the most recent iteration of NAND memory.
Like the eMMC, the UFS technology has also been upgraded over the years. At the time of writing this post, UFS 4.0 was the latest version incorporated in the latest high-end phones. Since 2015, the majority of the phones include the UFS technology, and the eMMC tech has been dropped.
UFS 1.0
The first version of the UFS technology was released in 2011 by JEDEC. It had a single lane and a 300MB/s bandwidth. However, a year later, JEDEC upgraded this technology and launched UFS 1.1. However, it did not offer great improvements.
UFS 2.0
UFS 2.0 was released in 2013. It offered 2 lanes in total, with 600 MB/s speed per lane, making a total bandwidth of 1200 MB/s.
Samsung’s Galaxy S6 and other variants were the first to receive this storage technology.
UFS 3.0
UFS 3.0 changed the game by more than doubling the total bandwidth that UFS 2.0 offered in 2018. With 2 lanes in total and 1450 MB/s speeds, it summed up to a whopping 2900 MB/s bandwidth.
UFS 3.0 also supports multiple Replay Protected Memory Blocks (RPMBs) with multiple keys. Hardware partitions called RPMBs are used to safely store important data, such as DRM content protection keys and user payment information.
UFS 4.0
Introduced in 2022, and currently the latest UFS version, UFS 4.0 offers 2 lanes and 2900 MB/s speed per lane. This makes the total bandwidth availability at 5800 MB/s for reading and writing data. This is possible with the integration of the V-NAND technology, which was built on top of the NAND flash memory, integrated with other technology.
The MIPI M-PHY 5.0 High-Speed Gear 5 and UniPro2.0 have also been used, where the former enables engineers to double the potential data rate per lane, and the latter is a high-speed interface technology for interconnecting integrated circuits in mobile and mobile-influenced electronics with high-speed data flow.
On top of this, UFS 4.0 is said to be 46% more efficient in terms of power consumption than its predecessor – UFS 3.1. Moreover, it has Advanced RPMB, which is more secure and offers 1.8 times the performance of the technology in UFS 3.1.
The UFS 4.0 technology has a serial interface with a low pin count. It offers up to 1TB storage space in a single, 153-ball BGA package. Additionally, compared to the previous UFS versions, it can also be compacted in a smaller size.
UFS 4.0 is branded the number one flash memory type today since it offers up to 23.2 Gbps theoretical throughput.
Phone storage technology comparison: UFS 4.0 vs eMMC 5.1 vs predecessors
The table below summarizes the speeds and performance comparison of the different storage technologies found in cell phones:
Technology | Version | Released | Bandwidth per lane (MBps) | Number of lanes | Aggregated max. bandwidth | M-PHY version | UniPro version | Sequential Read Speed (MBps) | Sequential Write Speed (MBps) | Random Read (IOPS) | Random Write (IOPS) |
UFS | 4.0 | 2022 | 2900 | 2 | 5800 | 5.0 | 2.0 | 4200 | 2800 | – | – |
UFS | 3.1 | 2020 | 1450 | 2 | 2900 | 4.1 | 1.8 | 2100 | 1200 | 100,000 | 70,000 |
UFS | 3.0 | 2018 | 1450 | 2 | 2900 | 4.1 | 1.8 | 2100 | 410 | 63,000 | 68,000 |
UFS | 2.2 | 2020 | 600 | 2 | 1200 | – | – | 1000 | 260 | 58,000 | 50,000 |
UFS | 2.1 | 2016 | 600 | 2 | 1200 | 3.0 | 1.6 | – | – | – | – |
UFS | 2.0 | 2013 | 600 | 2 | 1200 | 3.0 | 1.6 | – | – | – | – |
UFS | 1.1 | 2012 | 300 | 1 | 300 | – | – | – | – | – | – |
UFS | 1.0 | 2011 | 300 | 1 | 300 | – | – | – | – | – | – |
eMMC | 5.1 | 2015 | 250 | 2 | 500 | – | – | – | – | – | – |
Future of phone storage technologies
While UFS 4.0 still has a promising future, the world seems to be moving toward the forms of storage options, such as external storage and cloud storage. However, the phone itself will still need further innovation.
As of 2024, 1TB of physical storage offered by UFS 4.0 should be enough for the average consumer, but we will soon be seeing an upgrade from this figure, seeing the trends of our ever-increasing storage requirements.
At the moment, there are no rumors of further developing a new storage technology. However, UFS 4.1 is soon bound to hit the market with the upcoming processor Snapdragon 8 Gen 4 and so forth.