There is no operation that can reduce the count of erase-write cycles for each erase block. Possibly yes for a heavily-used drive, because deferring TRIM operations can cause increased write amplification and accelerate the (limited number of) erase-write cycles of erase blocks. Note that because a TRIMed LBA no longer has a physical block mapped to it, any scheme to write (a sector of) all ones or all zeroes cannot simulate a TRIM operation. Otherwise an unused (per OS/filesystem) LBA that is not TRIMed will be needlessly maintained by the SSD's FTL as valid data. The FTL can then unmap the physical block that was assigned to the LBA and make that physical block free and erased. The TRIM operation is the synchronization mechanism for the the OS/filesystem to notify the SSD's FTL that a LBA is no longer used (e.g. But to the SSD, each of these accessed LBAs is always treated as valid at the FTL level and has a mapped physical block (until the LBA is TRIMed). This reduces the pool of free physical blocks.Īs the OS/filesystem uses the SSD by creating, writing, reading, and deleting files, the LBAs can change between free and used states at the filesystem level. If the write is for a LBA that has no physical block mapped to it, then a free physical block has to be mapped to the LBA, and then the sector data can be written. This write amplification at this stage can slow down this fundamental drive operation of write a LBA. If a free physical block is not readily available, then a time-consuming sequence of read-erase-write operations is required. If this LBA already has a physical block mapped to it, then wear-leveling requires that the original physical block to be unmapped and made free.Ī (different and erased) free physical block has to be mapped to the LBA, and then the sector data can be written. Whenever the host PC writes to a LBA, the SSD is being informed that the LBA is valid. have useful/valid data).īecause of the FTL and wear-leveling, the SSD has its own concept of which LBAs are valid, and another level of book-keeping for which physical flash blocks are valid. To be clear, the OS/filesystem has its own concept of which storage blocks (LBAs) of the partition/drive are in use (i.e. That can reduce the occurrence of write amplification, which is the root cause of "the SSD gets slow". Activating trim can boost an SSD, but does it has any impact when I do it?įrequent TRIM operations allow the SSD's FTL to maintain a pool of free physical blocks that is as large as possible.
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