NAND flash cells are organised in terms of pages and blocks. A page is a cell within a grid, and each row of cells is a block. SSDs become slower as they fill up. a new ssd will be fast as there are loads of empty pages that can be written to streight away. when the drive is full it has to copy files to its memory to right to an open page.
If a file is to be updated, this cannot be done in situ. The relevant block containing the pages must be copied to main memory and updated. It will then be written to a new area of the disk and the original block(s) will be erased.
Hard Disk drive often a slower form of media storage
Network Attached Storage
connection using the local network. uses the standard: windows: SMB/CIFS linux: NFS MacOS: AFP