[Rtai] SCSI/IDE or other solutions?
mantegazza at aero.polimi.it
Thu May 15 09:17:36 CEST 2008
Hossein Aminaiee wrote:
> I need to log some data to a file from RTAI/LXRT task with a data baud
> rate of about 10MB/s. And I have two solutions in mind:
> 1. Opening a file and simply logging the data to the IDE hard disk.
> 2. Installing a SCSI hard disk and using possibly available API for the
> SCSI interface.
> I wonder if anyone knows whether RTAI has API for the SCSI interface so
> the task won't switch to the Linux/NONrealtime mode?
> Is there any other solutions?
> Appreciate any helps in advance.
The solution is to use a buddy Linux task/thread, enabled for RTAI but
not made hard real time, that receives data from the hard real time LXRT
task using RTAI IPCs, speediest is shared memory, maybe with with non
blocking SCB support, and then write to disk using standard Linux. See
You might want to give a try to the available native RTAI support for
sync/async Linux servers, see an example in CVS
My experience, an old one though, back to RTAI birth in 1999, showed
that with such a scheme logging 5 MB/s to disc was possible but not
easy. A large buffering was required to avoid loosing data and as a raw
as possible use of disk access functions required. There has been some
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