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How Does Flash Media Fail?
bhodge writes "Aside from the obvious 'it stops working' answer, how does flash media — such as USB, SD, and CF — fail? Unlike with traditional hard drive, where anyone who's worked with computers for a while knows what a drive failure looks like, I don't know anyone who has experienced such a failure with flash. I've haven't been able to find more than scant evidence of what such failures look like at the OS level. The one account I have found detailed using a small USB drive for /var/log storage; it failed very quickly, and then utterly (0 byte unformatted device), after five years of service in the role. This runs contrary to other anecdotal claims that you should still be able to read the media after you can no longer write to it. So my question is: what have you seen of the nature of flash media failure, if anything?"
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He'd taken it out of his camera, tried to put it back in, and nothin'. Slapped it into my Linux box. It "saw" that there was a device there, but wasn't real happy about it:
[ 5555.618324] sd 4:0:0:0: [sdb] Add. Sense: No additional sense information
[ 5558.777567] sd 4:0:0:0: [sdb] Sense Key : No Sense [current]
"It's dead, Jim."
I'm tempted to try the old hard-drive swaparoo: get the exact same SD card, unsolder the flash chips, and put the bad one's flash on the new one's circuitry. See if it's the circuitry that's bad, or the flash, itself. If anyone has any bright ideas on how to determine definitively which it is without me going through that exercise, I'm all ears.
Why would a solid state device fail from multiple submergings? Especially if there is no current running through it during said submergings?
Slashdot's rate-of-post filter: Preventing you from posting too many great ideas at once.
Mine is a beast. I washed it at least twice, still worked, and then most recently ran over it twice. Once backing up, and again coming back up the driveway when i 'forgot' it inside. Not realizing i had dropped it. I found it when i got home and it was crushed. Removed the metal around the USB connector since it was a pancake, plugged it in while holding it and the dang thing still worked. However since i'm lazy i don't want to hold it in forever so it's been retired.
A few weeks ago /. linked to a really wonderfully written article by Anand Lal Shimpi about SSD drives. In the article he includes some simple and clear explanations of how flash memory works, its lifespan, and how it handles writes and deletes to maximize the life of every block of storage.
http://www.anandtech.com/printarticle.aspx?i=3531
The only think missing from the article is a description of the behaviour of a failing drive.
About 5-6 years ago, I decided that it would be a good idea to build a small application on a flash drive, that is, code and compile it directly to the drive. :)
After what must have been hitting compile a few hundred to a thousand times, the 128MB thumb drive starting giving me drive write errors and then stopped responding altogether within about a minute after errors starting appearing.
I think the moral of this story is backup your data, even when it's on a flash based drive, and don't code directly on a cheap thumb drive
I had a 2 GB Micro-SD card in my phone fail on me; it also failed to write, but there was also data corruption of some of the contents that were already on the card.
The first symptom I encountered was that my backup program would report that it had failed to successfully back up the phone to the card. I popped the card out of the phone and into a PC, and noticed the data corruption in several places when trying to back up the contents - not just CRC read errors, but filenames actually turned to garbage, etc. in a couple of directories. After reformatting the card, the symptoms persisted - sometimes writes would fail, etc. Don't know what caused the failure, but that's what it looked like in my experience.
10MB CF cards predated the common deployment of wear leveling. Those old cards could fail at the drop of a hat. Especially if anyone was foolish enough to use them in a high-volume write situation.
Javascript + Nintendo DSi = DSiCade
I have a Philips DVD drive with a usb port, and was using a 1GB flash drive to play back video files copied from my PC. The drive failed relatively quickly - I'd had it for about a year, but hadn't used it all that often. I started to notice the video files were corrupt on playback, but initially suspected the file itself, or possibly a problem with the DVD player's decoder. I diagnosed the problem by copying a file onto the drive, then repeatedly checksumming it. The first couple of times, the checksum value would be often be correct, then on subsequent checks it would change on me. I'd end up seeing several different checksum values, never seeing it return to a previous value. Whether this was due to a problem in the interface harware when reading, or memory cells failing to retain their state, I don't know.
Even though it was a year old and I had no receipt, the manufacturer (Kingmax, I think?) was happy to send a free replacement. The new drive has seen much more use, but is still working fine.
I left one in my car on a hot sunny day without thinking about the consequences. When I went out and saw the device sitting on the front seat I was concerned. I took it in to my office and tested it. Windows didn't know what to do...
Linux said it was there, but could only read half of the files.
is packaging. There is stuff in the potting epoxy that holds enough electric charge to make the FET's gate start to conduct a little, playing havoc with everything. We've been having to redo parts with an extra layer of metal over the top of the IC to protect it from an intermittent contamination in our packaging material.
I believe I remember reading that Intel had problems with their water being mildly radioactive downstream of an old uranium mine, and running into the same problems (only much worse, since they're doing much finer geometry.)
So this is a case where the FET hasn't failed, precisely: it's just getting messed up by external interference.
Nostalgia's not what it used to be.
Seen this failure mode a lot too. Static build up on your body, then when you go to insert the device the charge jumps between you, through the device to the grounded casing around the USB connector.
Can do anything from reboot your PC (if you're lucky) to destroying the stick or the USB controller on the PC (or HUB if you're luck).
As you said power is a major problem with USB. Cheap USB sticks need FULL power to work right. Often times we'll have a customer with a stick that works fine in one PC (at home or work for instance) and will either not be recognized or will give read/write errors in another. Most of the time this is solved by using an external powered USB hub as the mother board simply isn't supplying enough voltage or current to power the stick. I'm not really sure if in general the problem is the motherboard or the stick as I haven't bothered to pull out the multimeter and do any serious testing, but I'm inclined to think its the stick as it seems to happen mostly with cheap/noname sticks that were probably rejected by the likes of Sandisk and co.
As far as pulling them out while the card is powered, that is part of the specification for SD and USB, not sure about compact flash, but I would assume its there as well. USB and SD have the connector configured in such a way to ensure power is applied and removed in the proper order, which is why their connectors have some contacts that are longer than the others.
What you said is still true however, a cheap chip on either side may not handle that process well. I can say however that we have successfully ran 3.3v SD cards at 7 to 9 volts for short periods of time due to mis configured testing setups where we didn't check the voltage after switching modes. Of course, we've also lost more than a few SD cards for that very reason, even at 5 volts they won't last more than a few minutes. mini and micro cards in an adapter to full SD fair better generally as the mini and micro's work at around 1.8v (I think, memory is fuzzy about that atm, might be 2.7) and have internal voltage dividers to cut down the 3.3 v input from the system, the still fail eventually due to over voltage, they just seem to do better although I have only anecdotal evidence to support that.
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
There may be other manners of failure. I have a recent 2Gb USB thumb drive that started going ever more slowly after a few days of use. I last measured a "dd if=/dev/random of=/media/device/test" of no more than 0.5kB/s. If somebody wants to have some fun analyzing it, I can put it in an envelope free of charge.
Non-Linux Penguins ?
I wonder how well that hammer thing worked.
It's beautifully effective for drives because they are high speed high precision mechanical devices, but even if you broke up the circuit board the chips were soldered to a guy with a soldering iron and some know how might still be able to get it back together again. Looking at that cell to gate progression posted earlier it sounds like unless you are able to actually destroy a given gate you don't destroy access to a give chip. If you were able to access the internals of the chip that might not be a barrier.
Too many electrons are easy to find though. Maybe get some rubber gloves, one of those hand held stun guns and zap the board parts a few times after (or before) you're finished hammering. It could be fun and sparkley. This also provides opportunity for some memorable conversations with management. " ...It's these SSDs boss. They're just really hard to erase when they fail. I'm afraid the department is going to need it's own Vandegraff generator..."
The blue smoke wants to be free.
Same here. I've washed SD and CF cards more often than I'd like to admit. Despite that I've never had one fail out of the wash.
I've had one card fail though. My Palm Treo uses SD cards and once when removing the card my fingernail was in the perfect position to split the card open at the seam. When I removed the card from the phone I had 2 pieces. One plastic cover(the part w/o the label) and the remainder of the card stayed together. I re-attached to cover and attempted to read the card in several USB readers and the phone as well. It was dead. The devices never recognized that a card was inserted.
There are lies, damned lies, and statistics.
I didn't make it clear that I was referring to the manufacturing side of things. I meant multiple chips reduced the chance of failures during manufacturing making the whole product unsellable. The more transistors to the package, the greater chance that some of them will be bad off the line. If the package can't tolerate any transistor failures and the cost per failed unit is high enough, you're better off building component chips indvidually then joining them on a PCB after validation.
Plus, many flashdrive manufacturers are assemblers and not chip fabs. They buy flash and controllers from various fabs and install them on PCBs in the apropriate combination to get their sizes. An external controller makes it easier to switch between producing 8GB, 16GB, or 64GB flashdrives since they only have to change the size and/or quantity of the flash chips.
Given the volatility in the flash market both to size and cost, I'm not sure it is financially viable to produce many memory+integrated controllers for anything but the largest bulk orders.
I haven't bought a retractable flash drive. Does the whole PCB slide within the housing or is there a flexible ribbon connecting the PCB to the USB connector? The former seems like it would be cheaper and more durable but the latter seems lazier and lazy seems to rule the day.
I've been on slashdot so long I'm starting to get out of touch with the cool stuff if it ain't on slashdot.
You might be the victim of one of the crooks who reprogram controllers in smaller flash to report as larger. It works fine until you wrap around and overwrite your file system. Beware of great deals on eBay.
Intron: the portion of DNA which expresses nothing useful.
Brand new 'Digitor Microdrive 4GB USB device'. Absolutely no response when plugged into main PC, and also no response when inserted into notebook (both USB2),with no other USB devices installed. Tried an external USB hub - no response. Vaguely remembered a report of someone accidentally dropping a USB thumbdrive into a cryogenic freezer, retrieving it and 'warming' it up slowly in a conventional freezer. He gained complete data recovery. As I of course do not have access to cryogenic facilities, I simply popped this problematic USB device into the freezer overnight, 'warmed' it up in the fridge during the day. Plugged it into the PC USB slot - Hey presto! Instant device recognition.