Write Amplification

• Each write requires programming a fresh page (a page that wasn't programmed since its block was last erased).
• Writing into the same LBA again - makes the specific page that contains the old data - invalidated.
• This can cause fragmentation, which will leave no fresh cells for writing, over time.
• Before this happens - the SSD will choose the least-valid blocks, copy their valid pages to an empty block - and mark all those blocks as free.
• These techniques may cause a single page write, to perform several page writes - write amplification.
• If each write causes two page writes on average, the SSD is said to have a write amplification factor of 2.
• Enterprise-Grade SSD designers employ complicated algorithms to reduce the write-amplification factor of their devices.

Originally written by guy keren