This is a discussion on Re: Slow tape drive timeout - Kernel ; Kai Makisara wrote: > On Wed, 2 Apr 2008, Robert Han**** wrote: >> Why is accessing the tape drive with no tape in it causing a timeout in the >> first place? I should think that would fail immediately with ...
> On Wed, 2 Apr 2008, Robert Han**** wrote:
>> Why is accessing the tape drive with no tape in it causing a timeout in the
>> first place? I should think that would fail immediately with some "medium not
>> present" error from the drive. Unless the drive has no mechanism to detect
>> it, but that seems really retarded..
> It does not seem retarded to me. If a program wants to just wait until the
> tape drive becomes ready (e.g., loads the tape), it can use the blocking
> open. This is simple.
This would be simple, if there were no timeout. Having the timeout, the program
must loop anyway.
> If a program wants to test the status, it uses
> non-blocking open. The behavior mandated by the standards provides
> alternatives. If O_NONBLOCK is not supported, the user program must
> implement the waiting logic if the program just wants to wait until the
> drive is ready before starting i/o.
Therfore a portable program SHOULD implement a waiting logic that won't burn
the CPU if there is no tape in the drive.
It's still sane to allow waiting for media change, but this applies to any
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