|
|
|
Question : Problem: Sandisk SD card dying?
|
|
Recently my Sandisk SD card seems to have been much slower than before, and its capacity had decreased. I reformatted the card (FAT), but lost another 217,088 bytes, or 200 KB. Is my card dying or just being used improperly? I use it solely for taking pictures from a digital camera (Argus DC3520) and transferring files between 2 PCs (by using Sandisk ImageMate 8-in-1 card reader). I purchased it last December and used it very infrequently (the total rewrite cycles is less than 20). Could it be dying? Someone know how to fix this?
Thanks in advance.
|
Answer : Problem: Sandisk SD card dying?
|
|
Freshair,
See comment on this SanDisk...
http://sdprob.aximsite.com/theproblemlist.htm
http://freespace.virgin.net/jon.crawford/theproblemlist.htm
AFAIK, your card is ok. See the info...below.
Endurance
SanDisk SD Cards have an endurance specification for each sector of 100,000 writes typical (reading a logical
sector is unlimited). This far exceeds what is typically required in nearly all applications of SD Cards. For example,
even very heavy use of the SD Card in cellular phones, personal communicators, pagers and voice recorders will
use only a fraction of the total endurance over the typical devices lifetime. For instance, it would take over 10 years
to wear out an area on the SD Card on which a file of any size (from 512 bytes to maximum capacity) was rewritten
3 times per hour, 8 hours a day, 365 days per year.
With typical applications, the endurance limit is not of any practical concern to the vast majority of users.
Wear Leveling
Wear-leveling is an intrinsic part of the Erase Pooling functionality of SD using NAND memory. The SD Cards
Wear Level command is supported as a NOP operation to maintain backward compatibility with existing software
utilities.
Using the Erase Command
The Erase (sector or group) command provides the capability to substantially increase the write performance of the
SD Card. Once a sector has been erased using the Erase command, a write to that sector will be much faster. This is
because a normal write operation includes a separate sector erase prior to write.
Memory Array Structures Summary
Part Number / Block Size (Byte) / Data Area + Protected size (Blocks) / Protected Area size (Blocks) / User Area (Blocks)
SDSDJ-1024 / 512 / 2,004,224 / 20,480 / 1,983,744
SDSDJ-512 / 512 / 1,001,104 / 10,240 / 940,864
SDSDJ-256 / 512 / 499,456 / 5,376 / 494,080
SDSDJ-128 / 512 / 248,640 / 2,624 / 246,016
SDSDJ-64 / 512 / 123,232 / 1,376 / 121,856
SDSDB-32 / 512 / 60,512 / 736 / 59,776
SDSDB-16 / 512 / 29,152 / 352 / 28,800
Hopes this helps...;-)
|
|
|
|
|
