SSD solid state drives have gradually become mainstream storage devices with their high-speed data reading and writing capabilities and reliable performance. Among the many optimization technologies of SSD, the TRIM instruction plays a vital role. It is mainly used to optimize the garbage collection mechanism and thus improve storage performance.
SSDs are composed of flash memory chips, and data is written to the flash memory in pages. However, there is a limitation in the write operation of flash memory, that is, the entire block must be erased before writing. When the SSD writes new data, if the corresponding block is already occupied, it needs to be erased first, which may cause some originally valid data to be moved to other locations, resulting in write amplification problems. Write amplification not only reduces write performance, but also accelerates the wear of flash memory chips and affects the life of SSDs.
In order to deal with the write amplification problem, SSD solid state drives use a garbage collection mechanism. The garbage collection mechanism automatically scans invalid data in the flash memory in the background, merges valid data into other free blocks, and then erases the blocks containing invalid data to make room for new data writing. However, without the TRIM instruction, the garbage collection mechanism can only determine whether the data in the block is marked as invalid to determine whether it needs to be recycled, which may cause some data that has been deleted by the operating system but has not been marked as invalid to still occupy space, affecting the efficiency of garbage collection.
The emergence of the TRIM instruction is to solve the above problem. When the operating system deletes a file or frees up disk space, it sends a TRIM instruction to the SSD to inform the SSD which logical blocks have no longer valid data. In this way, the main control chip of the SSD can know in advance which blocks can be erased, so that these blocks can be processed first during the garbage collection process, avoiding unnecessary read-write-erase operations and greatly improving the efficiency of garbage collection.
By promptly notifying the SSD which data is invalid, the TRIM instruction reduces the overhead in the garbage collection process, allowing write operations to find free blocks for data writing faster, thereby improving write performance. At the same time, due to the reduction of unnecessary erase operations, the wear of the flash chip is also effectively controlled, which helps to maintain the long-term stable performance of the SSD. In addition, the TRIM instruction can also reduce the delay during read operations because it allows the SSD to organize the data in advance, so that the read operation can locate the location of valid data more quickly.
When the operating system issues a TRIM instruction, the main control chip of the SSD solid state drive will map and convert the logical block address specified in the instruction with the physical block address in the flash memory, and then mark the corresponding physical block as erasable. During the garbage collection process, the main control chip will give priority to erasing and recycling these marked physical blocks, and migrate the valid data in them to other free blocks. After completing the data migration, the main control chip will initialize the erased blocks so that they can be reused for data writing.
The TRIM instruction is a very important technology in the SSD solid state drive. It effectively solves the write amplification problem by optimizing the garbage collection mechanism, improves storage performance, and extends the service life of the flash memory chip. For users, ensuring that both the operating system and the SSD support the TRIM instruction and keep it running normally can keep the SSD in a good performance state and give full play to its high-speed storage advantages.
