[daip] non-atomic file creation

[Eric Greisen]

Andrew Biggs wrote:
> Thanks Eric - I'll set QCREAT to True.
> 
> By the way, I came across an email from Craig Walker on the internet about
> problems with UVSRT and external disks on a MacBook Pro:
> 
> http://listmgr.cv.nrao.edu/pipermail/daip/2009-August/014621.html
> 
> Last night, I seemed to be experiencing the same problem and after UVSRT
> had run for several hours, I gave up, started MSORT instead and went to
> bed. This morning, I used UVSRT to return from BT to TB (I've UBAVG'd in
> the meantime) this time putting the external disk in BADDISK. This ran
> pretty quickly, although the file is smaller.
> 
> I'm on science leave in Manchester and have brought my data over on
> external disk. Is it in general a good idea to avoid external disks for
> scratch files?

UVSRT and some other tasks make a lot of scratch files and use them 
heavily.  BADDISK should be used to avoid scratch on slow disks, 
especially ones that may not be as well buffered by the OS.  Other 
tasks, IMAGR for example, have IN2DISK pointing at a heavily used work 
file - it would be good to set that value to avoid external drives.

I suspect that QCREAT will solve the atomic creation issue (the 
complaint - but you will be doing non-atomic creations effectively all 
the time).

Enjoy your science time...

Eric Greisen