NVMe (Non-Volatile Memory Express) SSDs (solid-state drives) are becoming increasingly popular for use in PCs and data centers due to their fast read and write speeds. However, like all storage devices, NVMe SSDs can and do fail. Understanding the potential causes of NVMe SSD failure can help users prevent failures and recover from them when they do occur.
Manufacturing Defects
Like any complex electronic device, NVMe SSDs can ship with manufacturing defects right out of the box. These may include:
- Faulty components – Defective NAND flash memory chips, controllers, capacitors, etc. can lead to premature failure.
- Improper firmware – Bugs in the SSD’s firmware can cause crashes, blue screens of death, and data corruption.
- Contamination – Dust, bits of metal, oil, etc. inside the SSD case can lead to short circuits and electrical issues.
Reputable SSD vendors have quality control processes to minimize shipping defective drives. But some fraction of bad drives inevitably make it past testing. Carefully vetting vendors and avoiding no-name brands can help reduce the odds of receiving a drive with manufacturing defects.
Write Amplification
Write amplification refers to the increased amount of data physically written to an SSD compared to the logical data written by the host system. It stems from the SSD controller having to erase full blocks of NAND flash before writing new data. For example, changing 1 MB of a 100 MB file may require erasing and rewriting the entire 100 MB block that the file occupies.
Higher write amplification wears SSDs faster by causing more program/erase cycles on the NAND chips. Consumer-grade QLC SSDs are particularly prone to write amplification with their relatively small SLC caches. Heavy random writes that prevent the SSD from consolidating data into large blocks also increase amplification.
Mitigating write amplification requires choosing SSDs designed for durability, with large SLC caches and advanced firmware. Enabling TRIM, limiting random writes, and leaving spare capacity can also help.
Excessive Drive Writes
The NAND flash memory in SSDs can only sustain a finite number of program/erase cycles before cells wear out and become unreliable. Most modern NAND is rated for anywhere from 500 to 5,000 P/E cycles.
Workloads that generate excessive drive writes will prematurely wear out an SSD. Examples include:
- Database servers
- Frequent transaction processing
- Virtualization hosts
- Media editing workstations
- Logging / temporary file operations
- Swap files
- Frequent rebuilds of RAID arrays
For write-intensive applications, choosing enterprise-grade SSDs designed for durability is a must. They feature more overprovisioning, better flash that tolerates more P/E cycles, and advanced wear leveling algorithms to spread writes across all cells.
Poor Power Supply
Because SSDs are electronic devices, a clean and stable power supply is critical to their healthy operation. Power issues that can impact SSD reliability include:
- Undervoltage – Insufficient voltage reaching the SSD can lead to instability or even component damage over time.
- Overvoltage – Excessive voltage delivered to the SSD risks damaging the controller or flash memory.
- Voltage spikes/drops – Momentary changes in voltage that fall outside device specifications can corrupt data or gradually degrade operation.
- Electrical noise – Ripple or interference on power lines can interfere with proper signaling between SSD components.
Using a high-quality power supply tailored to the system’s power needs helps prevent damaging conditions. Battery backup units, voltage regulators, and power conditioners can also smooth out the power delivered to an SSD.
Thermal Stress
SSD controllers and NAND flash chips optimally function within a fairly narrow temperature band. Excessive heat can accelerate failure mechanisms such as:
- Component oxidation and material breakdown
- Solder joint fatigue
- Electromigration of trace metalization
- Thermal expansion damaging encapsulation
Conversely, very cold temperatures can cause issues like:
- Brittle solder joints and components
- Increased electrical resistance
- Sluggish performance
Keeping drives within their rated temperature range requires adequate airflow and cooling in the system chassis. Hot-running drives may need supplemental cooling or relocation to a cooler part of the case. Severe thermal cycling also stresses drives.
Vibration
While primarily a concern for mechanical hard disk drives, vibration can also degrade the performance and longevity of SSDs over time. Specific problems include:
- Mechanical fracturing of solder joints
- Disturbance of precision electrical timing
- Eventual work-hardening and fatigue failure of components
Server chassis designed to dampen vibration and convert spinning fans to vibration-free liquid cooling can help. Enterprise SSDs also employ more mechanically robust components rated for higher vibration.
Internal Electrical Faults
Internal electrical faults within the SSD can develop over time and lead to failure. These include:
- Dielectric breakdown of insulators
- Flash cell electron trap wearout
- Electromigration within the silicon chips
- Oxidation or corrosion of electrical contacts
Such faults gradually accumulate through normal SSD operation as components age. But manufacturing flaws, excessive voltage/current, and temperature extremes can greatly accelerate their formation.
While unpreventable, using enterprise-class SSDs designed for longevity and avoiding environmental extremes helps maximize useful SSD life before such faults cause failure.
Controller / Firmware Failures
The SSD controller executes the firmware that manages all aspects of SSD operation. Failures related to the controller and firmware include:
- Bad firmware – Bugs, hangs, crashes, mismanagement of flash wear leveling and caching.
- Controller overheating – Insufficient cooling causes the controller SoC to overheat.
- Failed controller – Outright failure of the controller chip makes the SSD inaccessible.
Controller and firmware problems occur most often due to immature designs being rushed to market prior to adequate validation. Stress testing during the QA process helps minimize these issues. Overall SSD reliability depends heavily on the quality and robustness of the controller and firmware.
External Damage
External physical damage is another cause of SSD failure:
- Connector damage – Repeated plugging/unplugging wears out sockets and pins.
- Cracked PCB – Dropping or flexing the SSD can fracture solder joints or traces.
- Broken case – Impacts can split or crack the protective metal case.
- Liquid ingress – Spilling liquids into the SSD shorts circuits and corrodes metals.
Avoiding physical abuse and accidents helps prevent associated damage. Enterprise SSDs designed for servers feature robust casings, components, and connectors rated for frequent insertion cycles.
Encryption Key Erasure
Self-encrypting SSDs contain dedicated cryptoprocessors that encrypt/decrypt data on the fly using an encryption key stored in the drive. Erasing or corrupting this key renders all data on the drive inaccessible since it cannot be decrypted.
The key can be erased in several ways:
- Accidental overwrite by buggy software
- User error such as entering the wrong admin password too many times
- Intentional sanitization of the drive
- Component failure or power loss during key storage
Tamper-resistant cryptoprocessors minimize the risk of accidental key erasure. But intentional sanitization or failures during encryption operations still represent a risk.
Corrupted Firmware
An SSD’s firmware controls all of its functionality. If this crucial code gets corrupted or overwritten, the drive can experience anything from glitches to a complete inability to operate properly.
Firmware corruption typically occurs when:
- An incomplete or interrupted firmware update leaves firmware in an unstable state.
- Malware infects the SSD and overwrites portions of the firmware code.
- Errors occur during firmware erasure on used enterprise SSDs before reuse.
Robust firmware update mechanisms including fail-safes for power loss help avoid corruption. Physically isolating drives from potential malware infection also reduces risks. Careful secure erase procedures are needed when repurposing SSDs.
Endurance Exceeded
All SSDs have finite endurance determined by NAND characteristics. When an SSD exceeds its rated program/erase cycles or data writes, performance and reliability drop off until the drive fails completely.
Endurance limits vary tremendously across SSDs:
| SSD Grade | Endurance |
|---|---|
| Client/Entry-level | 100-300 P/E cycles |
| Enterprise Read-intensive | 1,000-3,000 P/E cycles |
| Enterprise Mixed-use | 3,000-10,000 P/E cycles |
| Enterprise Write-intensive | 30,000+ P/E cycles |
Choosing an SSD rated for the expected workload and utilizing features like overprovisioning helps maximize endurance. But eventually all SSDs wear out with sufficient usage.
Conclusion
NVMe SSDs remain quite reliable compared to mechanical hard drives when implemented thoughtfully. Choosing quality enterprise-grade drives designed for the expected workload and operating environment goes a long way toward minimizing failure risk. But like any electronic device, NVMe SSDs remain susceptible to wear and tear over time.
Understanding the potential failure modes allows mitigating risks through smart SSD selection, system design choices, monitoring, and maintenance. When failures do occur, this knowledge also facilitates identifying the most likely root cause for optimal recovery and replacement.
