How much damage does a forced shutdown do to SSDs? Nowadays, most computers are equipped with solid-state drives. However, our habits remain casual. For example, in situations like computer blackouts or crashes, people tend to directly force a shutdown. This direct power loss can turn the solid-state drive into a brick. Therefore, in today’s article, the YUNZE team will share with you the extent of the damage that forced shutdowns can cause to SSDs. If you’re planning to install or have already installed an SSD, let’s take a look together.
What is the extent of the damage to SSD caused by the forced shutdown? #
1. Forcibly cutting off power or performing a forced shutdown on the hard drive’s hardware has no impact. However, the hard drive can utilize the rotation of the disk after power loss to realign the magnetic head. But it affects the integrity of data. Generally, hard drives enable write caching settings by default to enhance write performance. After an abnormal power loss, ongoing write operations on the hard drive will cease, causing cached data to be lost, potentially affecting data integrity. This is also why some users experience their hard drives not being recognized after a forced power cut before restarting. However, there’s a method called ‘electrically idle for thirty minutes’ that can help. Another point to note is that power loss during writing significantly increases the probability of bad block counts rising. Fortunately, most solid-state drives are designed with spare blocks for replacement purposes.
2. Power interruption during the programming process of flash memory cells can lead to potential page damage, rendering them unusable. These damages can be mitigated by algorithms within the internal controller to prevent the SSD from becoming completely unusable. However, the inevitable result is that the lifespan of the SSD will be affected to some extent. If you have any questions or uncertainties, please don’t hesitate to contact us.
Principle of preventing data loss due to power interruptions in mechanical hard drives #
So, next, we need to understand the principle of preventing data loss due to power interruptions in mechanical hard drives. Here, let me give you an example: YUNZE has added a flash memory chip to its latest 10TB enterprise-grade mechanical hard drive, a component typically found in solid-state drives. During power outages, the rotational inertia of the disks generates electricity, which the main controller uses to transfer data from the DRAM cache to the flash memory for secure storage. This clever design ensures that data is not lost during power interruptions, achieving perfect data preservation even in the event of power loss.
For enterprise-grade solid-state drives, a common practice is to add power-hold capacitors to enable emergency writes to the cache data during power interruptions. However, this approach places limitations on the lifespan of the capacitors and might lead to unforeseen failures due to potential prior flash memory damage. As a result, this feature is not typically implemented in consumer-grade solid-state drives. In solid-state drives, the primary function of the DRAM cache is to store the FTL (Flash Translation Layer) mapping table. It supports a maximum capacity of up to 16MB to temporarily cache user read and write data. As Flush commands are issued, this cached data is then written to the NAND flash memory for permanent storage.
Test on YUNZE H-series 240GB SSD #
The Flush command is automatically scheduled by the Windows operating system and is used to compel the actual writing of data from the solid-state drive’s cache area to the flash memory for permanent storage. Below is a test conducted using the Toshiba H-series 240G solid-state drive. The H-series is an 8-channel MLC flash SSD manufactured by YUNZE and is currently one of the most cost-effective original manufacturer solid-state drives available.
- Use a manually operated software called ‘sync’ to verify the effect of the Flush command.
- If the power is cut immediately after completing file copying and the system is rebooted, the MD5 checksum of the files may be incorrect. This discrepancy occurs because some data remains in the cache and has not been physically written to the flash memory.
- If the Flush command is executed after copying the files, and then the power is immediately cut followed by another MD5 checksum verification, and the result is correct, it indicates that the files have been fully written into the solid-state drive.
The frequency at which the Windows operating system automatically sends Flush commands to the solid-state drive is rapid, so occasional forced shutdowns might not necessarily lead to issues. Additionally, the presence or absence of a DRAM cache is not strongly related to power loss protection for home computers. Even if you can safeguard the cache data of the hard drive, if the host computer lacks an uninterruptible power supply (UPS), the data in the main memory will still be lost. Furthermore, the instructions sent to the SATA interface during the moment of power loss might also be erroneous.
The primary objective of power loss protection for consumer-grade solid-state drives is to prevent flash write disturbance, which could damage the existing data bits in the same memory cell. Toshiba’s Q200 employs the Copy on Write approach to achieve this protection. When the solid-state drive needs to modify Page 3, it first copies the original content of Page 3 to a reserved area and then proceeds to write the new data to Page 3. If the write process is interrupted due to a power failure and an error occurs, the solid-state drive can recover using the data that was copied beforehand.
Words in the end #
All the aforementioned experiences and theories clearly illustrate the potential harm caused by forced shutdowns to SSDs. Therefore, it’s advisable for users to refrain from frequently subjecting SSDs to abrupt power cuts. Such actions could lead to unforeseen consequences. Occasional forced shutdowns need not be overly concerning, as SSDs can still function normally. If you have any questions or uncertainties, please feel free to contact us.
