190 times higher endurance than SSD disks

[Armin@netPI]

Since a month netPI is available in a 32GB byte FLASH memory version.

Time again to specifically highlight the extraordinary durability of the new 32GB SD card compared to SSD disk drives.

The 32GB SD card has an endurance of 1920TBW(Terrabytes written) or 1.92PBW (Petabytes written). This makes makes a ratio of 1920/32 = 60

Here is a collection of typical SSDs from the market and their ratio

• SSD Western Digital - model number WDS250G2B0A with 250GB: 100 TBW and a ratio of 100/250 = 0.4
  
• SSD Verbatim - model number Vi550SSD 49350 with 256GB: 150 TBW and a ratio of 150/256 = 0.58
  
• SSD Samsung - model number 750 EVO with 250GB: 70TBW and a ratio of 70/250 = 0.28
  

This make a 190 times higher endurance in the middle than commercial SSDs. Dont believe? Have a look yourself to the appended SSD datasheets

Thx
Armin

[COswald]

Hello Armin,

tha sounds very good.

This means, with this new card, the NetPI is also suitable for small database application?

What I'm searching for is a long time data queue. In case we lost connection to host computer, we can pump the data into the database to roll them out from where after connection is established again. and also be able to aquire new data while rolling up the old ones.


Kind regards,

Carsten Oswald

[Armin@netPI]

Absolutely correct Carsten.

A time series database like InfluxDB which is available for free can be used from now on and store data locally on netPI.

Till this 32GB SD card is getting physically destoyed or damaged in its FLASH memory blocks you and I will be already retired.

Thx
Armin

[tad]

Dear Armin,

Does the host OS (Linux) run on a microSD card or RAM (OS part is transffered to RAM after power-on)?

Thank you for your information.
Best regards,

[Armin@netPI]

A standard Linux OS works with both of course. After the boot sequence most of the Linux part is held in RAM after booting but whenever a file is written then it is cached in RAM first ... but after a while it is making the RAM cache empty by writing the file to the SD card finally.

During boot sequence Linux is just loading all drivers and executeable in RAM that are needed for execution. If there is something missing it is postloading it from SD card into RAM at later times. Sometimes if RAM is not enough, then Linux is starting to outsource data from RAM to SD card and vice versa.

[tad]

Dear Armin,

Thank you very much for your quick and kind explanations.

Best regards,

---

Sorry, I have one more question, please.

I'd like to know how often the host OS (Linux) accesses the microSD card.
That is the amount of data and access frequency that can be used as my own guideline when booting up netPI and during steady operation.
(I think at least Linux writes some log files to the microSD card.)

Then, I want to calculate the lifecycle of the microSD card by adding these situations and number of times that my own application accesses the microSD card.

Thank you very much for your cooperation.
Best regards,

[Armin@netPI]

Well the question "how often the host OS (Linux) accesses the microSD card" cannot be answered by anyone. I am no Linux expert. And of course this depends mainly on the type of containerized application that is in use.

My personal opinion is that if this is just an idle running Linux OS with no container the only reason to write to the SD card is the system log file written on any special event from time to time.

If you have a container running then Docker starts to write own log files to the SD card additionally. Especially if a container application usually outputs console information you see normally on your screen when running the container manually then this will be written to the log file instead of the screen. So in any case you have to take care of the application that is running additionally on netPI.

The worst case scenario of course is if your application is a database application. In this case any write to the database will lead to a write of the SD card.

Thx
Armin