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SD card flash life on Wx programs using Raspberry Pi

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miraculon:
I just replaced my SD card after experiencing problems with GUI log-in, graphs, HTML displays and general malaise with the meteohub based system. With the new SD card, everything is working as it should.

This was about a year and a half of operation. Meteohub is handling the data from several ISSs. I don't know if this puts more wear and tear on the flash than a simple single weather station system or not.

Has anyone else had to replace their SD card on their RaspPi yet? I also had another unit out in the garage that ran a camera and some PiFace utilities previously. This unit has been repurposed for another meteohub station monitoring a VUE console.

I found some "industrial grade" SD cards, especially the Panasonic one with SLC-lite technology.

They claim:

--- Quote ---The QE Series adopts MLC NAND flash memory with "SLC (Single Level Cell) Lite" access mode that provides higher endurance, data retention and power fail robustness than standard MLC products. An extended operating temperature
range of -25C to +85C is suitable for various applications. The integrated enhanced controller ensures long lifetime use and high system performance. Quality is maintained with 100% product screening before shipment to achieve low
failure rate. Storage capacity options include 4GB, 8GB and 16GB models
--- End quote ---

The true SLC SD card is $253, so that is too much. The SLC-Lite 16GB is $63, which is almost twice what the Pi board costs! If I have to go through this SD card replacement excercise again, I just might try it anyways.

Greg H.

Bushman:
I am moving all my Pis to USB stick OS.  http://myblog.furnissathome.co.uk/?p=384

miraculon:
Thanks for the tip and link. It seems that SD card corruption is common on the Pi. Fundamentally, though, the USB stick could suffer from the same issue couldn't it? The USB sticks have flash memory that is accessed via USB instead of the SD card's interface.

I found this on Wikipedia (although I was aware of the read/write life issue before):

--- Quote ---Longevity

The memory in flash drives is commonly engineered with multi-level cell (MLC) based memory that is good for around 3,000-5,000 program-erase cycles,[45] but some flash drives have single-level cell (SLC) based memory that is good for around 100,000 writes. There is virtually no limit to the number of reads from such flash memory, so a well-worn USB drive may be write-protected to help ensure the life of individual cells.

Estimation of flash memory endurance is a challenging subject that depends on the SLC/MLC/TLC memory type, size of the flash memory chips, and actual usage pattern. As a result, a USB flash drive can last from a few days to several hundred years.[46]

Regardless of the endurance of the memory itself, the USB connector hardware is specified to withstand only around 1,500 insert-removal cycles.[47]
--- End quote ---

This Multi-Level Cell memory may be the Achilles heel of running weather programs on the Pi.

With "3,000-5,000 program-erase cycles" as the life for MLC, using a RPi for a weather program sounds doomed from the start...

Maybe a USB HDD might work? Or maybe I will just treat it like my Davis DFARS fan, just part of an annual ritual..

Greg H.

Bushman:
I've read that about USB but I can tell you I have NEVER experienced a USB stick failure.  SD cards OTOH....  (never buy Kingston BTW).  An HD or an SSD would definitely work.  But they cost much more than the Pi itself (for a large one)  I was looking  at making a Pi into a NAS; could run the OS and the storage of the same drive.  BTW, you should clone whatever you use so that downtime is minimized.

Bushman:
https://learn.adafruit.com/external-drive-as-raspberry-pi-root/overview

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