fast mapcalc

[Tom Moore]

The original question had to do with improving access speeds for transient
datasets.  The suggestion of using a ram-disk type of setup seems like a 
good one, because it would be very easy to implement requiring no changes to
any of the grass programs.  Although 'ram-disk' is not the correct term to 
describe all unix implementations, it is convenient because most people 
understand the concept.  

There are a few implementation problems for grass that
have to be ironed out first.  Maybe the experts can help here.

How can you have permanent map layers reside on a 'real' disk and
transient files reside on the ram disk?  It seems that with grass the
only control that you have on placing files is by mapset, and all mapsets
reside in the file system under the same location.  Would you suggest
making a symbolic link from a location on a 'real-disk' to a mapset on 
a 'ram-disk'.

I guess it is possible to make a script that migrates a mapset 
onto a 'ram-disk' at the start of analysis, and then migrates it back 
to the real-disk at the end.  Maybe this is a very easy solution after all.

Tom
--
Tom Moore R.P.F.                                tmoore at pnfi.forestry.ca
Petawawa National Forestry Institute            
Canadian Forest Service, Box 2000, Chalk River  +1 (613) 589-3048
ONT K0J 1J0  CANADA                             +1 (613) 589-2275 telefax