Specifications

Appendix F - Flash Formatting Software

F-11

Performance Issues

TrueFFS performance in large part reflects the performance of the underlying Flash

technology: reading from Flash chips is extremely fast. In comparison, Flash write

(programming) and Flash erase are slow by one or two orders of magnitude.

TrueFFS usually displays blazing fast read speeds, which are much faster than the

customary speed of ordinary magnetic hard disks. Write speeds are similar to the

write speeds of magnetic disks: the TrueFFS write speed is a combination of the

Flash program speed and the Flash erase speed.

The TrueFFS write speed is not a constant. It depends on the amount of free space

(unused by user data) on the Flash medium. The more free space there is, the less

often TrueFFS needs to erase Flash components. In the extreme situation when there

is no free space, TrueFFS must erase frequently, resulting in a decline in overall

write performance on the TrueFFS drive. For this reason, the default formatting

capacity used by TFORMAT is 99%, which always leaves at least 1% free. You may

want to change this value to 90%, for example, by specifying /USE=90 in the

TFORMAT command, thereby sacrificing another 9% of disk capacity, but ensuring

good write performance at all times.

The amount of free space TrueFFS sees, and that affects performance, is the space

not used by files. Some applications, such as database managers, work by allocating

a large file (possibly encompassing the entire volume), managing space within this

file using their own methods. Such applications will work unnecessarily slow in

TrueFFS, as a result of the fact that TrueFFS is not aware of the free space within the

database.

Trouble-Shooting

The following DOS error messages may occur when working with TrueFFS drives.

They are usually followed by an ABORT, RETRY, IGNORE ? question.

MEDIUM IS WRITE PROTECTED

This indicates a failure by the hardware to turn on a 12-Volt current

which is needed when writing to Flash. This may be the result of an

inadequate power supply.