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8.8.1.16: MTSETDENSITY

C code
struct mtop op = { MTSETDENSITY, COUNT };
result = ioctl(tapefd, MTIOCTOP, &op);

Description

Set tape density (normally for SCSI tapes).


Notes

For ftape-3.04d (and later versions) this ioctl is used to tune the amount of debugging output produced by the driver. ftape-2.x and sftape used to utilise MTFSR (see MTFSR) for doing this. Trace levels control the amount of debugging output as follows:

  1. bugs
  2. + errors
  3. + warnings
  4. + information
  5. + more information
  6. + program flow
  7. + fdc/dma info
  8. + data flow
  9. + everything else

This works only if the driver has been compiled without the `-DNO_TRACE_AT_ALL' flag (see TRACE_FLAGS). Setting the trace level to a value >= 5 heavily affects ftape's behaviour: it is more or less unusable. The reason for this is simply the fact that printing to the system console is rather time consuming and therefore has a bad impact on the timing of the driver.


Example

disable all debugging output

mt -f /dev/nqft0 setdensity 0

Example

trace the program flow of the driver

mt -f /dev/nqft0 setdensity 5

References
Testing ftape
TRACE_FLAGS

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