On Dec 11, 2012, at 10:26 PM, Mohamad Chaarawi <[email protected]> wrote:

> Of course, a much simpler way to do this is to create the file using 
> MPI_COMM_SELF, create the data sets independently as you did since collective 
> on comm_self is well, independent, and close the file. 

Ahh wait sorry i was not thinking right since it will be the same file. this 
will not work as bad things will happen with this access pattern so disregard 
this.. 

Mohamad


> Then you can actually open the file again using comm_world, open the dataset 
> for each process (H5Dopen is not collective), then access the dataset for 
> each process independently as you were doing.
> 
> Mohamad
> 
> 
> On Dec 11, 2012, at 10:19 PM, Mohamad Chaarawi <[email protected]> wrote:
> 
>> 
>> 
>> On Dec 11, 2012, at 9:33 PM, Suman Vajjala <[email protected]> wrote:
>> 
>>> Hi,
>>> 
>>>  I thank you for the replies. The problem is that for creating a dataset 
>>> using H5Dcreate every processor has to know that dataset's size. Is there a 
>>> way of of doing it without the processors knowing the data size.
>> 
>> If the dataset size if based on the process rank, then you can just 
>> calculate that at each process then call H5Dcreate collectively on all 
>> processes for each dataset. If you can't calculate that size at each 
>> process, you can use MPI_Allgather to distribute the size for each process 
>> to all other processes then you would be able to call the H5Dcreate n times.
>> 
>> This is a limitation currently in the HDF5 standard that we plan to relax in 
>> the future. But this work is still in the prototyping stage. Ping me early 
>> January and might have a beta version that you might be able to use.
>> 
>> Mohamad
>> 
>>> 
>>> Regards
>>> Suman 
>>> 
>>> On Wed, Dec 12, 2012 at 8:58 AM, Elena Pourmal <[email protected]> 
>>> wrote:
>>>> reate ia
>>> 
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