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Thanks for the responses. I think I was off by an exponent. I knew
there was the subarray limit, but had it at 2^32 rather than 2^31.<br>
<br>
I have a few other things to report too.<br>
<br>
First, I believe I found a bug in the ncmpidump tool. For a
multidimensional variable of size (x,y,z), ncmpidump reports the
variable dimensions as (x,x,y) and which leads the data output to be
incorrect as well.<br>
<br>
Secondly, I have successfully created a variable size of > 4GB using
a 3d-multidimensional variable, without using the UNLIMITED dimension,
so this is good news. I tested creating a variable up to 32 GB without
problems. Next I tried to put additional variables into the file, but
it appears that any variables after the first one are still cut off at
4GB. Is this a known issue? <br>
<br>
I am working with a group who needs to write out about ~50 16GB
variables for a production run. There are a number of different work
arounds but right now we have to focus on performance. The current
implementation puts each variable in a separate file, but we are
finding the overhead of opening and closing files to be high which is
why I am trying to test putting all or at least some of the variables
in the same file.<br>
<br>
Katie<br>
<br>
Wei-keng Liao wrote:
<blockquote
cite="mid:Pine.LNX.4.64.0808112253520.12369@delta.ece.northwestern.edu"
type="cite">
<pre wrap="">Hi, Katie,
The development of the new pnetcdf 64bit integer format is still in its
very early stage. Dr. Kui Gao here at Northwestern is working on it.
The reason of why 1D array with more than 2^31 elements is not work is
because the current pnetcdf's implementation calls
MPI_Type_create_subarray() and its arguments are defined as int (32bit
integers). Rob R., Rob L. and we are all aware of this problem. Kui is
implementing an alternative approach now. Once this is done, we will
update the source asap.
As for the integer type, my suggestion is to use MPI_Offset, rather than
int64_t. int64_t is for internal implementation. Using MPI_Offset in
application programs is more portable and consistent.
Wei-keng
On Mon, 11 Aug 2008, Katie Antypas wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi Rob,
I am testing out the new pnetcdf file format which is supposed to allow
variable sizes greater than 4GB (as long as they have fewer than 2^31
elements). I am running on the Franklin Cray XT4 system at NERSC with
the PGI compilers and have not successfully created a 1d variable size
larger than 4GB. (I'll try multi-dimensions soon.)
I pass "NC_CLOBBER | NC_64BIT_DATA" to ncmpi_create now. Also, I was
getting type warnings and noticed a new type int64_t in places where
type int and MPI_Offset were used before in a number of calls. What is
your recommendation to users regarding the int64_t type? Should they
replace MPI_Offset with int64_t?
In either case though, if I do or don't make any changes to the ncmpi
calls (namely ncmpi_create, ncmpi_def_var, ncmpi_put_vara_double_all)
then I can only create a variable up to 2GB variable size which is under
2^31 NC_DOUBLE elements in a 1 dimensional array. (If we were counting
bytes, rather than doubles my test would be at the 2^31 elements limit.)
I didn't think this was the way elements were counted though?
Katie
</pre>
</blockquote>
<pre wrap=""><!---->
</pre>
</blockquote>
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