[Paraview] xdmf with field data in multiple files

[Peter Brady]

I've been using an xdmf file like the following:

<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Xdmf SYSTEM "Xdmf.dtd">
<Xdmf Version="2.0">
   <Domain>
     <Topology TopologyType="2DCoRectMesh" Dimensions="256 512"/>
     <Geometry GeometryType="Origin_DxDy">
       <DataItem Format="XML" NumberType="Float" Dimensions="2">
        0.00000E+00 0.00000E+00
       </DataItem>
       <DataItem Format="XML" NumberType="Float" Dimensions="2">
        1.22718E-02 1.22959E-02
       </DataItem>
     </Geometry>
     <Grid Name="TimeSeries" GridType="Collection" 
CollectionType="Temporal">
       <Time TimeType="List">
         <DataItem Format="XML" NumberType="Float" Dimensions="2">
          0.00000E+00 1.00399E-01
         </DataItem>
       </Time>
       <Grid Name="0" GridType="Uniform">
         <Topology Reference="/Xdmf/Domain/Topology[1]"/>
         <Geometry Reference="/Xdmf/Domain/Geometry[1]"/>
         <Attribute Name="density" Type="Scalar" Center="Node">
           <DataItem DataType="Float" Precision="8" Dimensions="256 512" 
Format="Binary" Seek="224">
            rstrt.0000.bin
           </DataItem>
         </Attribute>
         <Attribute Name="temperature" Type="Scalar" Center="Node">
           <DataItem DataType="Float" Precision="8" Dimensions="256 512" 
Format="Binary" Seek="0">
            rstrt.0000.6.bin
           </DataItem>
         </Attribute>
         ...
       </Grid>
...
</Xdmf>

However, as the simulations have gotten larger, the time to write a 
single file like "rstrt.0000.bin" in parallel has become obscene. My 
plan is to have groups of processors write different files where the 
extents written will be a continuous slab of ijk coordinates. I've 
looked at the documentation for hyperslabs in xdmf but can't quite see 
what changes I would need to make to make to my xdmf file.  For example, 
do I only need to change the innermost "DataItem" or do the changes need 
to be made higher up?

Some guidance on how to modify my xdmf file would be greatly appreciated.

Thanks,
Peter.