6. Appendix
IPC-BX955 User’s manual
103
Life of CF
About write endurance
CF contained in IPC-BX955D-DCx5x or IPC-BX955D-DCx6x has a write endurance which limits the
number of times each memory may be written, due to the characteristic of the memory that is used. Write
endurance can be calculated by the following formula as a reference value:
Write endurance (cycles) =
Total capacity (MB) x 100,000 (cycles) / Size of file (MB)
Example1: When the file of 1MB is made for the standard CF (2GB) for IPC-BX955D-DC556, and it
rewrites it once a second.
Write endurance = 1920MB x 100,000 cycles / 1MB = 192,000,000 (cycles)
Longevity = 192,000,000 / (3600 x 24 x 365)
6 (year)
After all these are reference values, confirm its life span by the following S.M.A.R.T.
About S.M.A.R.T.
A self-diagnosis program "SMART" that can obtain the S.M.A.R.T information in a CF is available for
download at TDK website. Following information can be obtained using this program:
1. Number of flash memory chips mounted inside CF, and the total number of blocks
2. Total number of write cycles on CF
3. Number of write cycles of the block where rewriting occurs most frequently
4. Number of write cycles of the block where rewriting occurs least frequently
5. Number of write cycles of all the blocks (10 step histogram)
The NAND type flash memory’s life span is 100,000 cycles. The number of write cycles for each block
can be determined, making it possible to predict life span.
TDK website:
http://www.tdk.co.jp
At the SMART program download destination:
http://www.tdk.co.jp/memorycontroller/mem01000.htm
Requirement for SMART program:
Windows 2000/XP with VB6.0 runtime and MSFLXGRD.OCX component
(such as vb6rt330.exe)
Figure 6.2 S.M.A.R.T.