Solid state drives (SSDs) are becoming increasingly common in computers due to their speed, durability, and reliability compared to traditional hard disk drives (HDDs). However, SSDs can and do fail occasionally. In this article, we’ll examine the most common causes of SSD failure and how to avoid them.
Wear and tear
Like all storage devices, SSDs have a limited lifespan. Data is stored on NAND flash memory chips inside the SSD, and these chips can only withstand a certain number of read/write cycles before they start to wear out and eventually fail. This is known as “write endurance”. Most modern SSDs are rated for anywhere from a few hundred to a few thousand terabytes written (TBW) before failure.
Heavy and prolonged usage, such as that in a server environment, will cause an SSD to wear out faster. When the drive approaches its write endurance limit, it is more likely to start having issues like bad blocks and performance degradation. The key to maximizing SSD lifespan is to not hammer it with an excessively heavy write load.
Read disturbs
NAND flash memory in SSDs is organized into pages and blocks. When data is read from a page, nearby pages in the same block can be disturbed, causing potential bit errors. These are known as “read disturbs”. Over time, read disturbs can accumulate and eventually lead to data loss and drive failure.
The probability of read disturbs is highest in TLC (triple-level cell) SSDs compared to MLC/SLC ones. The denser storage in TLC NAND makes it more vulnerable. Newer SSDs include read disturb management and “refresh” mechanisms to minimize this issue. But extensive reading over the drive’s lifespan does take a toll.
Write amplification
Write amplification refers to the amount of data actually written to an SSD compared to what the host system requested. For example, a write amplification of 2x means 2 units of data are written for every 1 unit requested. This amplification happens because of activities like garbage collection and wear leveling.
Higher write amplification causes more write operations and added stress on the NAND flash. It wears out the drive faster. An SLC SSD generally has write amplification around 1.1x, while a TLC drive can see amplification of over 3x. Properly optimized firmware is key to reducing unnecessary writes.
Power outages
Suddenly cutting power to an SSD while it is writing data can lead to corruption of in-flight data or metadata. The drive may become unresponsive or entirely unbootable after that. Many modern SSDs have capacitors to provide power for a brief period to allow pending writes to complete in the event of power loss.
Unexpected power interruptions are especially risky in server environments with constant write loads. Using an uninterruptable power supply (UPS) provides a consistent power feed and avoids this problem.
Controller or firmware bugs
The controller and firmware are the brains of an SSD, managing all the sophisticated functions like caching, wear leveling, error correction, etc. Unfortunately, bugs in firmware code can occur, especially in drives from less reputable manufacturers. Such bugs can lead to crashes, blue screens, or even bricked drives.
Always keep the SSD firmware updated to the latest stable version. Research the SSD brand and model online to check if others are reporting firmware issues. And have proper backups, so buggy firmware does not result in irrevocable data loss.
Excessive heat
Heat is the enemy of electronics. SSDs are designed to operate within certain temperature limits. But consistently running too hot can degrade NAND flash chips and other components over time.
Causes of excessive heat include inadequate airflow in the computer case, heavy read/write loads, too many drives crammed together, and high ambient temperatures. Monitoring SSD temperatures and improving cooling helps avoid heat-related failures.
Physical damage
While SSDs lack the moving parts of a hard drive, they are still vulnerable to physical damage from drops, shocks, vibrations, etc. The solder joints or components on the circuit board can crack or break under excessive mechanical stress.
Avoid putting SSDs in environments prone to vibration or movement, like in vehicles. Shipping or transporting SSDs calls for proper antistatic packing. Never handle bare drives roughly. Physical damage often appears immediately but can also later cause deteriorating performance and eventual failure.
Background maintenance issues
SSDs perform background tasks like garbage collection, wear leveling, and flash block refreshing. These tasks help maintain performance and extend drive lifespan. If background maintenance gets interrupted frequently, it can lead to degraded performance and premature failure.
Activities like editing large files, gaming, and running virtual machines can halt background maintenance. Allowing sufficient idle time enables the SSD to catch up on needed maintenance. Trim support and firmware optimization also facilitate efficient maintenance.
Insufficient over-provisioning
Over-provisioning refers to spare NAND flash capacity set aside by the manufacturer solely for the SSD’s internal needs. It improves performance and endurance. A minimum of 7% is recommended for consumer SSDs, while enterprise models call for 20-40% over-provisioning.
Some budget SSD models have very little or no over-provisioning. The lack of spare capacity for background tasks accelerates wear and shortens the drive’s lifespan. Checking reviews and specs to confirm adequate over-provisioning helps avoid early failure.
Low-quality components
Not all SSDs are created equal. Cheaper models may use lower-grade NAND chips with fewer program/erase cycles. Critical components like the controller or DRAM cache may be cut back to control costs. Such compromises lead to more errors and faster deterioration of performance.
Stick to reputable SSD brands that do not skimp on build quality. The savings on a bargain SSD often come back to bite you down the road in headaches and loss of the drive. Paying a little more for quality is wise in the long run.
Insufficient TRIM support
The TRIM command lets the operating system notify the SSD which data blocks are no longer in use and can be erased. This avoids unnecessary writes when cleaning up stale data.
Lack of TRIM support results in sub-optimal performance and premature wear-out. Make sure TRIM is enabled in your OS and SSD firmware. File systems like ext4 and XFS support TRIM, while FAT32 does not.
Fragmentation
When files are repeatedly modified and deleted, leftover data chunks get scattered randomly across the SSD’s flash blocks. This fragmentation forces the drive to work harder during reads/writes since data cannot be accessed sequentially.
Periodic defragmentation realigns data to minimize fragmentation. Optimum file system choice also plays a role. The ReFS file system is inherently resilient to fragmentation, while NTFS is more prone.
Bad blocks
Bad blocks or bad sectors refer to NAND flash memory that has failed permanently at the hardware level. They are unable to reliably store data anymore. Bad blocks tend to increase as an SSD ages.
The SSD controller manages these bad blocks by swapping in spare good blocks to take their place. However, if the number of bad blocks exceeds the spare capacity, the drive will start to malfunction and eventually fail completely.
Conclusion
SSD failure can result from a range of causes. However, smart usage and maintenance habits can significantly extend an SSD’s lifespan and avoid premature failure. This includes monitoring health metrics, managing heat, avoiding excessive writes, proper OS optimization, dealing with bad blocks, and not skimping on key components. Paying attention to the signs like performance changes or reallocated sectors can help address issues before complete drive failure.
