Question:
How can I calculate how much space a historic file will occupy in the hard disk?
Solution:
To do so, consider this:
- File header: 24 bytes.
- For each field, add 40 bytes.
- For each record, add 2 bytes of the register’s CRC plus each field’s size, as seen below:
char/byte = 1 byte
short/word = 2 bytes
long/dword/float = 4 bytes
double/datetime = 8 bytes
string = number of characters
Therefore, in a historic with two fields (one datetime, and the other one double) and 1000 records, the calculation is:
Header = 24 bytes
Two fields = 40 * 2 = 80 bytes
Each record = 2 + (8 + 8) = 18 bytes
Total size = 24 + 80 + (18 * 1000) = 18104 bytes
