SanDisk 2Gb Micro SD Memory Card Problems
I did not mean to put myself up as an authority on SD memory cards but, through a number of forum sites the problems described are all of a similar nature and I am receiving a lot of email regarding problems with these cards. I am posting this on all forum sites in the hope this will make things a little clearer.
Firstly one must understand exactly how a memory card works. The SD 1.0 documentation produces a string code which all computers will recognise. The card stores blocks of binary information in 'clusters'.
In the original SD format it stores 4096 clusters with up to 512 blocks, each block containing 512 bytes of information. This gave a card capacity of 4096 x 512 x 512 = 1 Gigabyte. These cards typically came pre-formatted to the FAT-16 file system with the MBR partition scheme. This meant that any computer or host type device would recognise them through a card reader .
Now for the rub.....With the advent of high capacity cards the string code went to SD 2.0 documentation, the block capacity was increased from 512 bytes to 1024 and 2048 giving a capacity of 4096 x 512 x 2048 = 32 Gigabytes, and these cards can only be formatted to the FAT32 file system.
For this reason an SD card reader will not recognise the data stream from a SDHC card. The situation is being further complicated because there is now an XC (extended capacity) card on the market which has a capacity of 2 terabytes (2048 Gigabytes) but this is at present being limited to 64 gigabytes by the SD 2.0 documentation.
What all this means is.....you don't use a 5 ton crane to move a 10 ton rock.....doesn't happen. If you wish to use an SDHC card (the card will be branded SDHC) you must have an SDHC card reader. The reader will access the information so the computer can handle it. This is why a lot of people complain the card will work in their phone but not their computer.....the phone has an inbuilt HC reader which the computer can access through USB .
The first thing you must do when you purchase your SDHC card and SDHC card reader is to format the card to the FAT32 file system otherwise you will not get the rated capacity out of the card......this is also a common complaint. Also, under no circumstance do a defragmentation on the card. All the clusters are equally accessable so there is no need and you will only wear the card out quicker.....remember these cards do have a finite life and the more you re-write them the sooner they will wear out.
Sorry....I don't want to sound like a 'know-all' but I have been using these cards since they were released onto the market and, like you, I have had to learn through trial and error.
I have a JVC card camcorder and I use 32Gb and 16Gb cards in this camera. My computer is something of a dynosaur by todays standards being a pentium 4, 3gb processor, 512 mb RAM and a 7,200rpm 120Gb hard drive but, I have no problems accessing and using these cards, no matter what the make, but as I have said, I have made it my business to find out what makes these cards tick.
Hope this is of use.....and potentially cuts back on my email traffic.......Rob... and greetings from Aussie land.
Dec 05, 2007 |
Network Storage Systems