Memory management with NVS

RE: Memory management with NVS

SwRa — Tue, 01 Aug 2023 08:15:56 GMT

Hi Garrett,

[quote user="garrettb"]re-using the same records all the time [/quote]

In this case, you don't need to manually implement sector erasing since you are not saving it as a new record.

Regards,

Swathy

RE: Memory management with NVS

garrettb — Fri, 28 Jul 2023 18:50:19 GMT

Hi SwRa,

I think I understand what you are saying.

What I am saying is this:

I will be saving about 10 variables in Flash.
I will be reading them all, on power up.
At run time, one or more of these variables will be updated, from time to time - depending on user interaction.

That's it.

So in that case, I suppose I have 10 stored records - re-using the same records all the time (whenever user interactions determine that I need to update one or more variables).

So do I have to manually look after sector erasing etc., or will that be done automatically by the NVS system?

Thanks

Garrett

RE: Memory management with NVS

SwRa — Thu, 27 Jul 2023 12:55:18 GMT

Hi Garret,

[quote user="garrettb"]My code will be writing to Flash to update a single variable, whenever that variable is changed.[/quote]

It will only be updating a single value in an already stored record in this case right.? Or is it that you are planning to store the new value as a new record.?

f you are just updating a value in the record, then it would be erased when a sector becomes full. You can read about flash wear here: https://docs.zephyrproject.org/latest/services/storage/nvs/nvs.html#calculating-expected-device-lifetime

However, if you keep storing new data as a new record, then there is no mechanism to erase the old data to get space for new data.

Regards,

Swathy

RE: Memory management with NVS

garrettb — Mon, 17 Jul 2023 17:01:42 GMT

Hi Swathy

Thanks for the response.

I read the post you refer to.

The information is not too clear though.

From reading that post, it seems to state:

If you are using only one variable, and you keep over-writing that variable, then the NVS system will look after tidy up / erasing, when a sector becomes full
If you are continuously writing new data, the NVS system will NOT look after the tidy up / erasing. Instead, when it eventually runs out of space, the write function will return an error.
If you have, say, 10 variables, and some of these are being updated from time to time, then...???

In the end, I have about 10 variables I want to store in Flash. My code will be writing to Flash to update a single variable, whenever that variable is changed.

Question: Will the tidy up / erasing be managed automatically by the NVS system, or will I eventually run out of space?

Regards

Garrett

RE: Memory management with NVS

SwRa — Fri, 14 Jul 2023 09:34:44 GMT

HI Garrett,

Take a look at this ticket: NVS sector erase

Regards,

Swathy