How many times can a flash drive be rewritten?

How Long Do Flash Drives Last? USB Drive Lifespans

Although flash drives fulfill numerous purposes even in the age of the cloud, like all technologies, they are not without limitations. One of the primary drawbacks of flash drives is their limited lifespan.

Understand how the life expectancy of a typical USB flash drive is measured, how long flash drives last before experiencing issues and how to mitigate these problems and extend your drives’ lifespan.

How a Flash Drive’s Life Expectancy Is Defined

Unlike many other devices and appliances, the life expectancy of a flash drive is not typically measured using units of time such as years and months. Instead, the technical term for the life expectancy of a flash drive or any device using flash memory is measured in write/erase cycles. Consequently, a flash drive’s maximum estimated number of write/erase cycles is called «write endurance.»

A write/erase cycle, or simply a write cycle, is the process of writing data into the flash memory controller. A flash drive’s controller can withstand a finite number of write/erase cycles before it begins failing. Past this point, data corruption starts to settle in.

Therefore, the life expectancy of a flash drive is defined not strictly by its age but rather by its usage rate. The more frequently you use your flash drive — or, more specifically, change data on it — the more write/erase cycles you complete and the more quickly its flash memory cells wear out.

How Long Can a Flash Drive Last?

The maximum write endurance of wholesale flash drives varies significantly depending on the manufacturing processes and the quality of the materials utilized during manufacturing. A USB drive’ longevity also depends on the type of connector used, such as a USB-A vs. USB-C, and the overall build quality of its circuits and protective shell.

Average values vary widely. Most devices can withstand between 10,000 and 100,000 cycles. Low-quality products may last fewer than 10,000 cycles, while cutting-edge drives made using the latest technologies can reach one million or more.

Although many manufacturers provide an estimated lifespan for their devices (typically 10 years), this value is an estimate based on an average user’s yearly write/erase cycles.

Using a drive less frequently than these assumed values may result in the drives lasting longer than 10 years. Frequent usage wears the drive out more quickly and shortens its lifespan well under the 10-year estimate.

In theory, if you write data to a USB-C memory stick once, then store it appropriately for 10 years before inserting it into your computer again, your data should be safe and your drive should function almost like new.

Symptoms of a Failing Flash Drive

Generally, if a given flash drive is approaching the end of its life, the read and write speeds will decrease well below its factory performance. In practical terms, low read/write speeds translate to files taking a long time to be inserted into your drive. Eventually, the memory cells will break down and fail, and the user will begin experiencing more severe issues.

Symptoms of a failing flash drive include the following:

• Your computer refuses to recognize your drive, even though it is formatted/you know it has data on it
• The available space on your drive is reduced compared to its advertised capacity — for example, less than 1 GB remaining on a nominally 32 GB drive
• You are experiencing signs of data corruption, such as unreadable or inaccessible files

How Can I Extend My Drive’s Lifespan?

Although you cannot add lost write cycles back to a worn-out drive, you can take a few preventative measures to extend the drive’s remaining life and ensure it lasts as long as possible. Try the following tips:

• Handle your USB drives with care: Physical damage and rough handling are more likely to reduce your drive’s lifespan than frequent usage. Careful handling helps prevent premature damage, wear and tear. Always use the protective cap to protect your USB connectors during transportation, and do not forcefully insert or rip your drives out of your devices.
• Do not use your USB drive like a hard drive: Directly editing files loaded on a drive or running programs from a USB drive can result in excessive read/write cycles, leading to premature wear. Move or copy the files from the drive to your computer first, make your edits and then move the edited files back to the drive instead of doing it directly from the device.
• Do not leave your USB drives plugged in: Even if you don’t move files to and from your drive, leaving a drive plugged in causes the OS to periodically check on the drive to ensure it is still there, which wastes write cycles. If you are done using your USB and won’t need it for a while, unplug it.

Purchase High-Quality Custom USB Drives Today

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Recharge Your USB Flash Drive Today or Say Goodbye to the Files Tomorrow

I know, I know. The title will inevitably raise some eyebrows. Rest assured, though, by the end of this brief post it will make perfect sense.

A couple months ago I sat down to sort out my USB thumb drive collection. I have 10 of those used either to move large files between distant machines, as OS installation and recovery media, and to actually store some non-critical data. While going through the inventory I eventually plugged in the USB stick I brought back from my Summer 2018 trip to Japan. The last time I used it was around September 2018, when I transfered some video clips from the PlayStation 4 to study while building my Dynamic Sloshing Liquid Rig.

Which means the drive was left unused for 3 years.

Imagine my surprise when I found out that two out of three short in-game video clips were corrupted. The first clip wouldn’t even copy over to the PC, while the other one took its sweet time and eventually, after about 30 minutes (for a 100 MB file), succeeded in getting copied to the HDD.

Overwhelmed by avid curiosity I immediately fired up the video player.

What you see here is the result of physical data corruption (a.k.a. «bit rot» or «data degradation» or «data decay»). While such graphic and «movie-like» damage is, funny enough, quite fitting to the overall presentation of Horizon: Zero Dawn — a game about hunting mechanical dinosaurs in a post-apocalyptic world, — this incident begs the question.

What Happened?

To answer it, let’s briefly recall how a Flash Drive actually works.

For any Operating System a USB Flash Drive is just a block storage device with address space divided into 512 byte sectors. So when the OS needs to address a specific data block it sends an appropriate command to the controller and either reads or writes data.

Looks and sounds simple, right?

Well, in actuality, the NAND memory such drives are based on comes with lots of quirks and complications. Long story short: LBA (OS-level) access needs to be translated into NAND-specific order of commands: sometimes it needs to erase the blocks, or only write data in a specific order, or log the number of reads and writes to each memory block e.t.c.

All of those steps are absolutely necessary for the drive to be both practical and robust, due to the fact that the number of times each NAND memory block can be overwritten is strictly limited. Such command translation is performed by the drive’s controller which functions as a Flash Translation Layer (FTL). It accepts LBA commands, does the required NAND operations and returns LBA-compliant response.

What a lot of users don’t know, is that the controller also performs another very important set of operations: garbage collection, wear leveling and bad block management.

NAND Flash Memory Wear Leveling

Now recall once more that NAND blocks can only be overwritten so many times before they become unusable. Therefore, before writing anything to NAND the controller must decide which blocks to distribute the data over, to ensure that all blocks get worn out evenly. While it’s easy to make use of «fresh» blocks, the chip also needs to closely monitor ones which undertook lots of writes, since those are highly likely to fail either on their own, or upon another read/write operation. Therefore sometimes the controller needs to take existing data and physically move it to another block to for safe storage.

This is complicated even further by the fact that before allowing to be written into, any block must be erased. This set of operations is called Garbage Collection (GC) and it’s essential for the drive’s endurance and secure data storage, and can only be performed while the drive has power.

No Time to Explain, Get In the Car!

When you use the drive to write data, to ensure high write performance, the controller looks for previously «erased» blocks to put data into. While this doesn’t sound like a problem, consider how USB Thumb Drives are usually used: you put the drive in, quickly write the data onto it, then almost immediately take it out of the device and put the drive into your pocket.

Garbage Collection, sort of like automatic defragmentation, is performed while the drive is idle. And since your common USB Stick gets little to no time «for itself», it cannot effectively perform such «house-keeping» operations as data relocation (from «older» NAND blocks to «fresh» ones) and erasure of unused blocks for future write operations.

As a result of such use scenarios, over time the USB Stick becomes much slower, for at some point it runs out of ready-to-use blocks and needs to erase old ones during immediate writes. Because, of course, erasing files via the OS only marks them as deleted on the file system level, the parts of the drive where those files are physically stored aren’t really changed. At least, by the OS itself.

The lack of «NAND-level» erased blocks causes write speeds to drop down significantly, which can be perceived as the drive «dying».

But it gets even worse. To relocate data from one block to another, the controller needs some already erased blocks to be freely available. And if it had no time to physically erase unused blocks prior, it wouldn’t be able to perform this data-critical operation due to alleged lack of available fresh blocks.

And as a result of that — blocks die or lose charge over time and the data loss occurs.

Oh No! What Do?

With power provided, and given enough idle time, the Flash Drive controller can work as intended and perform Garbage Collection in the background, ensuring it’s nice and ready for future uses and safe mid-term data storage when unplugged from the device.

All you need to do is from time to time plug your USB Flash Drives into your PC or other host device and let them sit idle for some time.

I can’t assert exactly for how long, but believe an hour or more should suffice, depending on the drive’s capacity and space used. This will give the NAND controller precious time to perform «house-keeping» and will prolong the life of both your drive and the data on it, as well as help maintain its maximum read/write speeds for much longer.

SSDs Too by the Way

This advice is valid for almost any type of a flash storage device, including Solid State Drives.

If for some reason you prefer SSDs over HDDs for long-term data storage (which is a terrible idea, by the way) make sure to plug those drives in at least once a year and let them sit idle for a day or two. Especially if your drive uses cheaper TLC or QLC memory cells which are highly prone to charge loss over time.

Multi- (MLC) or Single level (SLC) cell drives are also susceptible, so don’t think you’re safe simply because you shelled out for a more expensive drive. It will eventually lose charge or flip bits if left unpowered long enough.

Story Time

As long as we’re talking NAND data loss, I’d like to share a peculiar incident that happened about a year ago.

I use an MLC-based SATA SSD as a system drive. It’s fast, has good endurance and never showed any signs of excessive wear. Then one day I powered up the PC to discover that my Windows user profile was damaged and the OS loaded up into a default one. My user folder and the files were still there, but the OS refused to load it up, saying the registry was corrupted.

Luckily, thanks to the 3-2-1 Backup Strategy, a recent backup is always available, so I easily recovered the system partition and decided to inspect the files. Just as I thought: it wasn’t a virus or anything — upon closer inspection and after comparing the corrupted file to the original, I discovered mismatched bits in the damaged registry file in two places. How exactly this happened — I’ll never know, but all signs point to either some random cell charge leak or maybe even a bit switch caused by cosmic radiation.

No. I’m not kidding:

After all, we do live in a real, physical world. It’s highly volatile to anything that wants or needs to hold charge for extended periods of time. Therefore, even if you have a good Solid State Drive, you’re never 100% safe from data loss. Make sure to back your precious data up from time to time.

How many times can a flash drive be rewritten?

Flash memory is widely used to store data and code used in embedded systems. It is a non-volatile storage medium, meaning that it can retain data without a power supply. Flash memory can be electrically erased and reprogrammed and it erases data in units called blocks and rewrites data at the byte level. Flash memory is often used in systems that frequently rewrite data, such as USB flash devices or SD cards.

Flash memory is a variation of EEPROM, or electrically erasable programmable read-only memory. EEPROM and Flash memory have many differences, with one being their reading, writing, and erasure procedures of stored data. For instance, EEPROM can read, write, and erase data at the byte level while Flash memory can also read and write at the byte level, but can only erase data at the block level.

Because erasing is a relatively slow operation and must be done before writing, performing the erase in a large block makes large write operations faster.

Flash memory devices are often I2C- or SPI-protocol based to facilitate communication between two devices or chips in an embedded system. Depending on the application of the memory device, there are certain advantages and disadvantages of using one over the other.

Types of Flash Memory

There are two types of Flash memory most commonly acknowledged: NAND and NOR Flash. NOR Flash was the first of the two to be introduced in 1988 by Intel, while NAND Flash was later introduced by Toshiba in 1989. Their main differences can be identified in their architecture.

NOR and NAND are named for the way the floating gates of the memory cells that hold data are interconnected in configurations that resemble a NOR or a NAND logic gate.

NOR Flash

NOR Flash is optimized for random access capabilities where it is able to access data in any order and doesn’t require following a sequence of storage locations. In terms of its architecture, each of NOR Flash’s memory cells are connected in parallel where one end of the memory cell is connected to the source line and the other end is connected to the bit line. This allows the system to access individual memory cells.

NAND Flash

Conversely, NAND Flash is optimized for high-density data storage and gives up the ability for random access capabilities. NAND Flash cells are connected, usually eight memory transistors at time, in a series to the bit line called a string. Here, the source of one cell is connected to the drain of the next one. This series connection reduces the number of ground wires and bit lines.

In summary, NAND-based Flash memory is ideal for high capacity data storage, while NOR-based Flash memory is best suited for code storage and execution, generally in small capacities.

Examples and Applications of Flash Memory

Flash Memory Examples

Common examples of Flash memory include:

Flash Memory Applications

Flash memory is widely used for storage and data transfer in consumer devices, industrial applications, and enterprise systems.

In terms of consumer devices, Flash memory is often used in portable devices such as cell phones, digital cameras, tablets, and printers for fast and easy information storage. Flash memory is ideal for such electronics because it allows for mobility and miniaturization of the devices. With Flash memory, these devices can store data such as text, pictures, audio, and video files, and perform certain functions without the need for a traditional hard drive. Additionally, since Flash memory is non-volatile, these devices can store data without power, making it more efficient for consumers.

Flash memory is also often used in industrial computing applications, including scientific instrumentation, industrial robotics, space exploration, and medical electronics. Industrial systems often use Single-Level Cell (SLC) NAND Flash due to its reliability and endurance and its lessened susceptibility to power fluctuations. Incorporating such industrial-grade Flash storage is vital in these critical use cases as it minimizes risk of failures.

In enterprise applications, Flash storage refers to the use of solid-stage drives (SSDs) comprised of Flash memory for the mass storage of data or files. Enterprise computing platforms such as data centers benefit from SSDs as they offer high data throughput and low transaction latency. With the growth of hybrid and all-flash arrays, SSD storage serves intensive workloads with very high I/O performance.

How Total Phase Supports Flash Memory and EEPROM Devices

Total Phase offers multiple host adapter tools that support reading, writing, erasing, and verifying I2C- and SPI-based Flash memory and EEPROM devices. Depending on the speed and application, embedded system engineers can select from the Aardvark I2C/SPI Host Adapter, Cheetah SPI Host Adapter, or the Promira Serial Platform to program and interface with such memory devices.

The Aardvark I2C/SPI Host Adapter is a general-purpose host adapter capable of signaling up to 8 MHz as an SPI master and up to 4 MHz as an SPI slave. It also can emulate an I2C master or slave device up to 800 kHz.

The Cheetah SPI Host Adapter is designed to support high-speed programming applications, allowing users to signal up to 40 MHz as a master SPI device. It is able to support up to 3 slave selects and features a pipelined architecture that enables command queuing for maximum throughput.

The Promira Serial Platform is an advanced host adapter tool that is capable of signaling up to 80 MHz as an SPI master and 20 MHz as an SPI slave, and up to 3.4 MHz as an I2C host or slave device. It offers multiple other features for advanced programming which include supporting up to 8 slave selects along with support for Dual and Quad I/O.

The Flash Center Software is a software package that allows engineers to quickly erase, program, and verify I2C- and SPI-based EEPROM and Flash memory chips that are interfaced through Total Phase’s Aardvark I2C/SPI Host Adapter, Cheetah SPI Host Adapter, and Promira Serial Platform.

Unlike other programmers which can take minutes to program a memory device, the Flash Center Software can program the same device in seconds. The Flash Center Software natively supports a wide range of commonly used I2C- and SPI-based Flash memory and EEPROM devices, but it also allows users to easily add new parts if not already supported.