New Pi

A half-way decent one using lead-acid 'float' type batteries should do a *lot* better than that. At work we have one that is over 10 years old, with it's original batteries. We're in converted farm buildings so have frequent outages. Some short, some stuttery some hours. It's an on-line type so there is never a dip until it eventually shuts down (if everything is left on that long).

Though I now have 2 cards that run Rasbian as they should neither of them, nor the card that wont boot, show up on my Iyo or Win7 machines. Just get the message insert a card. That is starting to look like 2 duff card readers at best. Certainly does not allow me to try your chkdsk command. We seem to have problems with SD cards

Just tried a 'good' card again and after some jiggling the contents were displayed. Tried again, complete failure. When the card reader is plugged in the power light comes on; when the sd card is plugged into the reader the light goes off. They cannot be formatted ,checked or anything if they are not seen.

Malcolm Smith

IMO this shows that the SD card has been so badly corrupted that even its partition table can't be read. Its been several years since I've used DOS or Windows for anything significant, but IIRC fdisk is the DOS/Windows partition editor. So:

- can fdisk see the card

- if it can, can it create a FAT-32 partition occupying the whole card

- if the partition can be created, can it be formatted?

If all these work, try using Noob to set up a fresh install on the disk and let us know what, if anything, in that list works.

It is not unusual. I have a broken SD card here. When I put it in a cardreader, it is not seen at all. Commands that access the card issue "no media in drive" errors. Completely impossible to do anything at the level of fdisk/partition/format etc, it is just not seen anymore.

And that happened while it was in the cardreader! It was OK one moment, I dd'd an image onto it, it issued an error while writing, and then it was broken. No power glitches or whatever.

The only thing particular about this card was that it was a cheap Chinese fake card with a brand name on it.

Don't think that a brand name like "kingston" or "transcend" on a card or USB stick means it is genuinely from that manufacturer: there is a big industry of counterfeiting in China that fabricates cheap cards for sale on webshops. They often do not really have the capacity that is printed on them, but only are formatted to indicate that capacity. When you start using them beyond a certain point, they turn out to be very forgetful. Sometimes reformatting fixes that, but it also happens that the capacity that fdisk sees has been faked as well! You can only use those when you make a smaller partition that covers only the really usable area (and probably a second one to cover the remainder to avoid "clever" software extending the partition automatically)

That's a hard disk tool, if the SD card wont format, its not going to help. Bin it any buy another.

---druck

Understood.

It doesn't mean much anyway: Kingston buys in job lots of cards, applies its brand labels and sells 'em on. Dunno about Transcent - I've never used them. AFAIK Sandisk is about the only SD card maker that still makes their own cards.

Indeed. Some of you may find this an interesting take on SD cards in general and cheapie cards in particular:

====snip====

That just looks like a bad SD slot contact in the reader. I've got the same problem with the upgraded[1] card reader I fitted into a floppy disk sized drive bay. I tend to use a cheap Poundland SD to USB2 adapter now.

It's more than likely the bad contact was the original cause of those cards demise due to formatting or write operations.

When I get a "Round Tuit"(tm), I'm going to take a closer look at the card reader contacts. I might be able to retension the contact springs or resolder a dodgy joint.

Samsung have their own flash fabs so have end-to-end supply chains. SanDisk partner with Toshiba for fabs. SK Hynix does't sell to the retail market. Intel and Micron (Crucial) do, but aren't big in SD cards.

The rest just buy whatever's going on the open market.

But that still leaves your challenge in buying cards: Samsung or SanDisk may have assured supply chains, but is the thing you bought a genuine Samsung or SanDisk?

Theo

that's why I bought direct from Kingston. same price, guaranteed quality

Not sure I agree since the SD card cannot be plugged directly into my desktop computers and using the card reader the card cannot be seen I can do little using W7 or RiscOS. When the card is put in the Raspbery pi it boots up normally so does not appear to be corrupted. Currently card reader returned to shop since only purchased 2 days ago. Shop assnt agrees card reader looks suspect but seeks higher authority.

Malcolm

The three cards I have :- 1 with a raspberry on it and nothing else bought from the ,swag shop, 1 labelled Element 14 made in Korea and 1 labelled 'C Team' and made in Taiwan. The first 2 pre-programmed with

Malcolm

Just opened up one card reader for a look Loads of electronics. A spring loaded contact which closes when card inserted and that seemed OK so I guess the problem is with the electronics. Re-assembled and still would not read a good card

Malcolm

You're likely to find that most/all SD card readers are connected via an internal USB hub - built-in readers as well as the external and obviously USB connected ones.

However, be that as it may, it may be a good idea to pick up at least one for use with your RPi, so you can copy the card. I have a Kingston SD only reader and a StarTech multi-format reader. Both have been around for a while and both have 'just worked' on every computer I've used them with. I generally stick to SanDisk cards. FWIW my preferred supplier ATM is Ebuyer.

With an extra card and reader you can use the dd utility to clone your complete boot card on the RPi. Plug in the USB reader and put a new card in it. This should be the same size as the boot card and, preferably, carry the same (reputable) brand name. First use 'df' to check the names of the card drives: most likely the boot card will be /dev/sda and the one on the USB card reader will be /dev/sdb, so that the command

sudo dd if=/dev/sda of=/dev/sdb bs=32M

will clone both partitions on your current card onto the new card, which should then be bootable.

Thankyou Martin. That is going to be very useful and bring some peace of mind.

Malcolm

One way to test an SD card or USB flash key (aka thumb drive) for capacity is to write a short script to create a file with known, non-repeating contents and write the file to the card or key. Something like "This is line $n.\n" for n = 1 to ... should do. A good pseudo-random number generator would also work. After writing the file, read it back and verify the contents.

Fwiw, A few years ago, when I ordered several units with manual write-protect switches, with a brand name that is not known as a major semiconductor maker, about half of the units failed. The vendor sent replacements, and about half of the replacements also failed. A Kingston USB flash key I tested with that method was perfect.

HTH

Most, definately not all. The one in my laptop shows up on the PCI bus. but the 3.5" bay-sized readers which connect to an desktop machine's internal USB header. a very common, as are external usb sd readers.

Ready-made programs for this purpose already exist. For example, for Linux the program F3 (f3write/f3read) exists that is designed to find unreliable or fake SD cards or USB drives.

For Windows there is H2testw

This should work most of the time (vast majority?) but it's not 100% fail safe. SD cards, even of the same brand and labeled capacity, may have slightly varying space, especially after lots of use. New cards SHOULD be good. You did say new :)

Not sure if it makes any difference but I always unplug the SD reader from the computer after a sync/eject rather than pulling the card out of the "live" reader.