ESP32 Forum

Hello,
I have started the process of working with NVS and have a question related to BLOBS.
I have a Array of 140bytes that I write into NVS as a blob.
When I use nvs_get_stats() I expected to see 6 entries equalling around 192 bytes but instead I see 7 entries taking 224 bytes.
My Understanding after reading the NVS Structure Entry information https://docs.espressif.com/projects/esp ... flash.html is that I should have 1 entry that contains 32 bytes that has that info about the Variable Blob. Then I should have my 140 byte array wrote to 5 entries at 32byte each (160bytes of NVS).

Can someone help me understand why I am instead seeing 7 entries taking up 224bytes of NVS? Looking at the NVS documentation I concluded that Either the Page Header is being reported as a entry when i do the nvs_get_stats() or to write a blob it requires TWO key-value pairs.
Because in those two scenarios I get 64 bytes of data used for over head and that leaves me with the 160bytes I expected that my array would be put into.. IE 5 entries at 32bytes of NVS.

Appreciate any help thanks.

"Blobs are allowed to span over multiple pages by dividing them into smaller chunks. For tracking these chunks, an additional fixed length metadata entry is stored called “blob index”. "

corz.org wrote: ↑

Mon May 08, 2023 9:58 pm

"Blobs are allowed to span over multiple pages by dividing them into smaller chunks. For tracking these chunks, an additional fixed length metadata entry is stored called “blob index”. "

I had read that in the Docs but thought it only added that header when it spans pages. Does it add that to every blob?
Because Every blob I write has 64bytes of data extra. Which would mean that all blobs get the second header even if they do not span pages?

That is my understanding, yes.