storageatomicdisksolid-state-drive

What is a atomic write unit for mordern SSDs?

My understanding is that a most modern spindle based drives have a "sector" as an atomic write unit. What is the unit for modern ssds?

Solution

  • I am not entirely sure what you mean by atomic write unit. I am assuming you mean the smallest unit of write.

    In a NAND-flash SSD, the smallest unit of read and write is called a page. Typically, page size would be 2kB or 4kB, plus metadata.

    Also, the smallest unit of erase is a few pages (32-128 pages).

    Sources:

    http://codecapsule.com/2014/02/12/coding-for-ssds-part-3-pages-blocks-and-the-flash-translation-layer/

    https://en.wikipedia.org/wiki/Flash_memory#NAND_memories