Have you verified which devb driver is running? With SP2 or SP3, QNX introduced a new powerful devb driver, devb-ahci. 
Before that, SATA controllers would be accessed in compatibility mode using devb-eide. Check if devb-ahci is running and
 if it does, try devb-eide instead. It will result in less good performance but may solve your cdrecord issue.

Good luck,

- Malte

> Posted on Momentics support forum before, but no response, so trying here - 
> sorry for crossposting.
> 
> This is about runtime kits QNX 6.3.0 SP1 and SP3.
> I know it's a bit old, but that's what we have.
> 
> On a computer with SATA CD-RW, cdrecord under SP1 works fine. However it fails
>  on that same computer under 6.3.0 SP3 with several "cdrecord: no such file or
>  directory. xxx: scsi sendcmd: fatal error" (with xxx = "write_g1", "test unit
>  ready", "flush cache", "close track/session", "prevent/allow medium removal".
> 
> 
> Both is after an installation of a fresh Runtime Kit CD and the installation 
> of cdrtools-201beta-bin-qnx.tgz downloaded from QNX.com.
> 
> I've just tried with an IDE drive in the same computer with SP3 instead, in 
> this case it works fine. However we need to go SATA (this is for a production 
> machine, and IDE drives are soon reaching end of life).
> 
> Any ideas about what I could do to make cdrecord work with SATA drives under 6
> .3.0 SP3?
> 
> 
> Thanks for reading
> Bernhard
>