Account for netCDF without HDF5 but with MPI.

* It is possible to build netcdf 4.x without HDF5 but with MPI
  parallelization support.

src/pio_cdf_int.c

@@ -51,16 +51,25 @@ cdiPio_nc__create(const char *path, int cmode, size_t initialsz, size_t *chunksi
   int status = NC_EINVAL, ioMode = commInqIOMode();
   if (ioMode != PIO_NONE)
     {
-#if CDI_PIO_TRY_PNETCDF
 #if !defined TLS && defined HAVE_PTHREAD
       struct cdiPioNcCreateLongJmpRetBuf *cdiPioCdfJmpBuf = pthread_getspecific(cdiPioCdfJmpKey);
-#endif
 #endif
       if (cmode & NC_NETCDF4)
         {
           cmode |= NC_MPIPOSIX;
           status = nc_create_par(path, cmode, commInqCommColl(), MPI_INFO_NULL, ncidp);
-          if (status == NC_NOERR) cdiPioCdfJmpBuf->openRank = CDI_PIO_COLLECTIVE_OPEN;
+          if (status == NC_NOERR) {
+            cdiPioCdfJmpBuf->openRank = CDI_PIO_COLLECTIVE_OPEN;
+          } else {
+            int rank = commInqRankColl();
+            if (rank == 0)
+              fputs("warning: parallel create not implemented"
+                    " for NetCDF4/HDF5 format!\n", stderr);
+            if (rank == cdiPioCdfJmpBuf->openRank)
+              status = nc__create(path, cmode, initialsz, chunksizehintp, ncidp);
+            else
+              longjmp(cdiPioCdfJmpBuf->jmpBuf, 1);
+          }
         }
       else
         {
@@ -123,7 +132,8 @@ cdiPioCdfDefVar(int ncid, const char *name, nc_type xtype, int ndims, const int
   int cf_format;
   int status = nc_inq_format(ncid, &cf_format);
   if (status != NC_NOERR) Error("%s", nc_strerror(status));
-  if (commInqIOMode() != PIO_NONE && cf_format == NC_FORMAT_NETCDF4)
+  if (commInqIOMode() != PIO_NONE && cf_format == NC_FORMAT_NETCDF4
+      && cdiPioNcID2OwnerRank(ncid) == CDI_PIO_COLLECTIVE_OPEN)
     {
       xdebug("%s", "calling nc_var_par_access");
       int status = nc_var_par_access(ncid, *varidp, NC_COLLECTIVE);

src/pio_server.c

@@ -1073,6 +1073,20 @@ cdiPioStream2Owner(int streamID)
   return rxWin[streamIdx].ownerRank;
 }
 
+int
+cdiPioNcID2OwnerRank(int ncid)
+{
+  size_t nstreams = openStreams.size;
+  for (size_t streamIdx = 0; streamIdx < nstreams; ++streamIdx) {
+    int streamID = openStreams.entries[streamIdx];
+    int ftype = cdiBaseFiletype(streamInqFiletype(streamID));
+    if (ftype == CDI_FILETYPE_NETCDF
+        && streamInqFileID(streamID) == ncid)
+      return rxWin[streamIdx].ownerRank;
+  }
+  return CDI_UNDEFID;
+}
+
 /* for load-balancing purposes, count number of files per process */
 /* cdiOpenFileCounts[rank] gives number of open files rank has to himself */
 static int *cdiSerialOpenFileCount;

src/pio_server.h

@@ -11,6 +11,9 @@ void cdiPioCollectorMessageLoop(void);
 
 int cdiPioStream2Owner(int streamID);
 
+int
+cdiPioNcID2OwnerRank(int ncid);
+
 #endif
 /*
  * Local Variables: