diff --git a/include/hdf5/hdf5_edge_attributes.hh b/include/hdf5/hdf5_edge_attributes.hh
index 1665140..d52e167 100644
--- a/include/hdf5/hdf5_edge_attributes.hh
+++ b/include/hdf5/hdf5_edge_attributes.hh
@@ -22,6 +22,8 @@ namespace neuroh5
   namespace hdf5
   {
 
+    // Constants for chunking
+    constexpr size_t EDGE_ATTR_CHUNK_SIZE = 1ULL << 30; // 1GB chunks for safety margin
     
     void size_edge_attributes
     (
@@ -92,13 +94,15 @@ namespace neuroh5
                             attr_name,
                             current_value_size);
 
+      MPI_Request request;
       size_t my_count = value.size();
       std::vector<size_t> all_counts(size, 0);
-      throw_assert(MPI_Allgather(&my_count, 1, MPI_SIZE_T, &all_counts[0], 1,
-                                 MPI_SIZE_T, comm) == MPI_SUCCESS,
-                   "append_edge_attribute: error in MPI_Allgather");
-      throw_assert(MPI_Barrier(comm) == MPI_SUCCESS,
-                   "append_edge_attribute: error in MPI_Barrier");
+      throw_assert(MPI_Iallgather(&my_count, 1, MPI_SIZE_T, &all_counts[0], 1,
+                                  MPI_SIZE_T, comm, &request) == MPI_SUCCESS,
+                   "append_edge_attribute: error in MPI_Iallgather");
+
+      throw_assert(MPI_Wait(&request, MPI_STATUS_IGNORE) == MPI_SUCCESS,
+                   "append_edge_attribute: error in MPI_Wait");
 
       // calculate the total dataset size and the offset of my piece
       hsize_t local_value_start = current_value_size,
@@ -126,10 +130,35 @@ namespace neuroh5
           string path = edge_attribute_path(src_pop_name, dst_pop_name,
                                             attr_namespace, attr_name);
           
-          status = write<T> (file, path,
-                             global_value_size, local_value_start, local_value_size,
-                             mtype, value, wapl);
-          
+          while (global_value_size - current_value_size > 0)
+            {
+              hsize_t local_write_size = std::min((hsize_t)EDGE_ATTR_CHUNK_SIZE, local_value_size);
+              std::vector<size_t> all_write_counts(size, 0);
+
+              throw_assert(MPI_Iallgather(&local_write_size, 1, MPI_SIZE_T, &all_write_counts[0], 1,
+                                          MPI_SIZE_T, comm, &request) == MPI_SUCCESS,
+                           "append_edge_attribute: error in MPI_Iallgather");
+              
+              throw_assert(MPI_Wait(&request, MPI_STATUS_IGNORE) == MPI_SUCCESS,
+                           "append_edge_attribute: error in MPI_Wait");
+              
+              status = write<T> (file, path,
+                                 global_value_size, local_value_start, local_write_size,
+                                 mtype, value, wapl);
+
+              if (local_value_size > 0)
+                {
+                  local_value_size -= local_write_size;
+                  local_value_start += local_write_size;
+                }
+              
+      
+              for (size_t p = 0; p < size; ++p)
+                {
+                  current_value_size += (hsize_t) all_write_counts[p];
+                }
+              
+            }
           throw_assert(H5Pclose(wapl) >= 0, "error in H5Pclose");
         }