Jennifer Adams <jma@xxxxxxxxxxxxx> writes:
>
> Thanks for asking a question for which there is an easy answer. Some of
> the recent support issues have been real stumpers!
>
> I'm glad it wasn't too tough, and also that the answer was 'YES'.
>
> There are functions to both set and learn about the chunk
> cache. Changing the cache settings only applies to future opens/creates,
> it does not affect already-open files.
>
> These don't tell you what the file was opened/created with, just the
> current settings. So if you change them, and want to know what they are
> for each file you open/create, then you must remember what they were
> when the file was opened/created.
>
> Let me see if I have understood properly ... The cache parameters are set
> on a per-file basis, but copied from global settings at the moment I open
> the file? And the original global settings are those used at compile
> time?Â
Yes and yes.
> What if I open a file, query the chunk and the cache sizes, and discover
> that the cache isn't big enough to hold a single chunk and my I/O is
> doomed. Do I have to close the file, reset the cache size, then open the
> file again?Â
Yes.
But does that really ever happen? The default chunk cache is 32 MB - do
you have files with chunks larger then that?
If so, you could either change the chunk size to a better default
setting before doing any opens, or you could use the --with-chunk-cache=
parameter of configure to change the default chunk cache size for that
installation of netCDF.
Is this not enough to meet all of your chunk caching needs?
Thanks,
Ed
--
Ed Hartnett -- ed@xxxxxxxxxxxxxxxx
