(I know this is a slightly old thread, but I felt that it was useful to share my experiences, and it didn't seem helpful to start a whole new thread on the same topic. Sorry if that irks some people.)
A couple of weeks ago, I was also experiencing the same symptoms as many others on my Raspberry Pi B+, running Raspbian (Linux raspberrypi 3.12.26+ #704 PREEMPT) from a Sandisk 64 GB microSDHC card.
It has been working just fine for a week or two, but then started becoming unresponsive, requiring a power cycle. I wasn't seeing anything interesting in the system logs, so configured rsyslog to forward log messages to a remote syslog server (in case the Pi wasn't able to write pertinent errors to the SD card).
Long story short, the next time this happened I was able to spot the problem in the log messages that were forwarded to my syslog server. The smoking gun appeared to be a sequence of I/O errors, followed by a "aborting journal on device" message, then a "remounting filesystem read-only". Obviously, based on the symptoms (and a load of similar experiences shared on these forums), I assumed this indicated some sort of SD card error. The problems always seemed to coincide with periods of increased I/O activity (e.g. downloading large number of new packages via apt-get).
So, I decided to re-format the SD card and re-install everything from scratch. I reformatted it using the official SD formatter (https://www.sdcard.org/downloads/formatter_4/
), then re-wrote the Rasbian image to it, and started again. However it failed again quite quickly (same types of I/O and filesystem errors) during an apt-get upgrade operation.
So I concluded that my SD card was knackered and bought a new one (this time a Samsung 16 GB card, listed here as 'working': http://elinux.org/RPi_SD_cards
) and started again with this one. To my intense irritation, the problem recurred again really soon with this card.
I decided that my least bad option would be to try to reduce write operations on my SD card as much as possible, so I bought a 64GB SSD drive (http://www.sandisk.co.uk/products/ssd/sata/standard/
), reverted to my original SD card (after all, it had previously worked OK for at least a week, unlike the other one), re-installed Raspbian, then followed paulv's excellent instructions (http://www.raspberrypi.org/forums/viewt ... 29&t=44177
) to move the root filesystem to the SSD drive -- effectively just using the SD card at boot-time, but then running the OS from the SSD drive via USB. My hope was that this would minimise use of the SD card, whilst using a better-suited drive to so the vast majority of the I/O.
Imagine my annoyance, then, when after 30 minutes of running just fine from the SSD drive, the same problems occurred again (except this time the errors pointed at the filesystem on my SSD drive, not the boot partition on my SD card). At this point, I was finding it hard to believe that I could have somehow chosen two different SD cards and one SSD drive all with the same defects and/or incompatibilities. I now had to assume that this was a hardware problem with the Pi itself.
So, I replaced the Pi with another B+ that I had lying around. I changed nothing else -- same SD card, same SSD drive, same power supply, etc. Everything worked fine, and it's been working flawlessly ever since.
I have to conclude then, that although my case initially showed all the symptoms of a problematic/corrupted SD card, in fact the problem was with the Pi itself
. If I hadn't taken the unusual step of switching to an SSD drive, I would have probably kept on assuming that these were just SD card problems.
It's hard to imagine what the true cause of the problem with the Pi were -- evidently something that affected I/O via the SD card interface and
USB, but I don't know enough about the Pi's hardware design to speculate about what that could be.
Anyway, apologies for the long rambling story, however I thought it would be useful to share this, in case it sheds any light on other people's problems. While I'm sure that many suspected SD card problems are just that: problems with the SD card, it's worth bearing in mind that in at least one case, the problem was nothing to do with the SD card, and lay with the Pi itself.