From Bits to Banks/Planes

Let's look at the architecture of a typical flash chip.

As they say in ancient Greece, storing a single bit (or a few) does not a storage system make. Hence, flash chips are organized into banks or planes which consist of a large number of cells.

A bank is accessed in two different sized units:

  1. blocks (sometimes called erase blocks), which are typically of size 128 KB or 256 KB

  2. pages, which are a few KB in size (e.g., 4KB)

Within each bank there are a large number of blocks; within each block, there are a large number of pages. When thinking about flash, you must remember this new terminology, which is different than the blocks we refer to in disks and RAIDs and the pages we refer to in virtual memory.

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