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[sheddyian]

I've a Raspberry Pi that I use to run DSLstats, but also runs energy monitor software called Measure-It.  This communicates with one of those free energy monitors that gas and electric companies were giving away free a few years ago, and plots real time graphs - like DSLstats, but for electricity!

Anyhow, that Raspberry Pi, named Faraday, stopped responding, and rebooting it didn't get it going.  It was running headless, so I couldn't see what was failing at startup.

I took it up the shed, made a backup of the SD card, then ran the Windows program HDTune on the card.  This plots a graph of transfer rate across the whole of a hard disk or other storage device.  A hard disk should have a gentle downward curve, SD cards and USB memory devices should have a flat line.

Looking at the attachments to this post :

faraday-1.png is the first scan of the card, showing large variations in read performance.
faraday-2.png is a repeat run, showing that the performance is similar, if not identical.

I then ran the SD format program on the card, using the overwrite erase option & format.

faraday-3.png is the run of HD Tune following the reformat.  Much better!

Note that the card wasn't failing as such, the whole card was readable, and I later re-wrote the backup image without problem.

But it's interesting how repeated re-writes by the Raspberry Pi do seem to have a (temporary?) detrimental effect on the SD card.

Ian

Software :

Measure-It http://lalelunet.github.io/measureit/  (many, including Raspberry Pi)
HD Tune (2.55 free version) http://www.hdtune.com/  (Windows)
SD Format https://www.sdcard.org/downloads/formatter_4/ (Windows/Mac)

[edit - I'd mixed up DSLstats with Routerstats.  The Pi is running DSLstats]

[roseway]

That's very interesting. I've always wondered how long an SD card would last when running a program like DSLstats, which makes frequent writes. There's a suggestion here of some partial rejuvenation.

[sheddyian]

That's very interesting. I've always wondered how long an SD card would last when running a program like DSLstats, which makes frequent writes. There's a suggestion here of some partial rejuvenation.

I've found this with SD cards in Raspberry Pis that have been used for some time, and reformatting with the SD card association SD Format tool will rejuvenate.  (I always do an overwrite format, not simple quick format using the tool).

I would imagine, but have no data to prove either way, that frequent writing from DSLstats (and indeed the electricity monitor, which uses SQL) is likely to tire the card out fairly quickly, but so far the only card I've had fail was one in my webserver. In that instance, the card was so bad that most of it's data was lost, and yet a reformat got it back to excellent condition and I couldn't get it to fail again.  Whether it's weakened is another matter...

Ian