Does reading an SD card a thousand times reduce its life?

Question

I know writing affect SDCard but I don't know about intense reading

Answer 1

The short answer is no, it does not. This is because the read operations does not involve moving electrons forcefully across the cell and uses much lower voltage than write operations.

The long answer is that flash memory and other similar Non-volatile memories (like Intel's DC-PMM) have very different mechanism for reading a bit compared to writing it. For flash memories a write involves applying a very high voltage across an insulator to tunnel electrons across it. This process when done repeatedly damages the insulator, rendering the cell unusable. The read however involves passing a small current near the insulator which does not damage the cell.

This is not to say that a read cannot damage a cell but, you'd expect its lifetime to be similar to what DRAM's lifetime is (for all practical and non-server use purpose it's infinite).

A very good explanation of all this is here.

Answer 2

Yes!

Contrary to the popular belief, yes, an SD card deteriorates from just reads. There's a similar question on our sister site: MicroSD card performance deteriorates after long-term read-only usage. Here's an excerpt from the accepted answer:

You're experiencing read disturb, a phenomenon where reading the same cell over and over again charges neighboring memory cells ever so slightly every time. […]

To avoid charging neighboring cells through read disturb, the controller takes oft-read cells and redistributes them after a threshold number of reads.

In other words, reading an area repeatedly makes it necessary to rewrite its neighborhood somewhere else.

I highly recommend reading the linked answer if you're interested in the details.

Answer 3

File systems keep track of several dates and times of each file. One of them is "last accessed". So it seems that reading from an SD card in practice also does some writing (to the file system bookkeeping (directories)).