diff --git a/src/engine.c b/src/engine.c
index 87f34ac765cfb09e5f34ac3e9d203285670cff23..9e4cbf59fd592552b670b32723dde7d136b71dd3 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -5628,9 +5628,8 @@ void engine_check_for_dumps(struct engine *e) {
         engine_print_stats(e);
 #ifdef WITH_LOGGER
 	engine_dump_index(e);
-#else
-	engine_dump_snapshot(e);
 #endif
+    engine_dump_snapshot(e);
 
       } else if (e->ti_next_stats < e->ti_next_snapshot) {
 
@@ -5662,9 +5661,8 @@ void engine_check_for_dumps(struct engine *e) {
         /* Dump snapshot */
 #ifdef WITH_LOGGER
 	engine_dump_index(e);
-#else
-	engine_dump_snapshot(e);
 #endif
+	engine_dump_snapshot(e);
 
       } else if (e->ti_next_stats > e->ti_next_snapshot) {
 
@@ -5684,9 +5682,8 @@ void engine_check_for_dumps(struct engine *e) {
         /* Dump snapshot */
 #ifdef WITH_LOGGER
 	engine_dump_index(e);
-#else
-	engine_dump_snapshot(e);
 #endif
+	engine_dump_snapshot(e);
 
         /* Let's fake that we are at the stats dump time */
         e->ti_current = e->ti_next_stats;
@@ -5723,9 +5720,8 @@ void engine_check_for_dumps(struct engine *e) {
       /* Dump... */
 #ifdef WITH_LOGGER
       engine_dump_index(e);
-#else
-      engine_dump_snapshot(e);
 #endif
+      engine_dump_snapshot(e);
 
       /* ... and find the next output time */
       engine_compute_next_snapshot_time(e);
diff --git a/src/engine.h b/src/engine.h
index 7dc3860097f3daaad3a2541fca9097eccf7b276a..dd2fc89b6944d53802164f958ae263f68ae9247a 100644
--- a/src/engine.h
+++ b/src/engine.h
@@ -326,7 +326,7 @@ struct engine {
   size_t logger_time_offset;
 
   /* Size of the dump file */
-  size_t logger_size;
+  size_t logger_buffer_size;
 #endif
 
   /* Need to dump a snapshot ? */
diff --git a/src/logger.c b/src/logger.c
index d1e79ad3d479c2dd00058ecb9becfefd731c3a45..00a11a0012dbdc6c1a0d7b6a4b406116891bd73e 100644
--- a/src/logger.c
+++ b/src/logger.c
@@ -61,7 +61,7 @@ const unsigned int logger_data_size[logger_data_count] = {
  *
  * @return updated buff
  */
-__attribute__((always_inline)) INLINE static char *logger_write_chunk_header(char *buff, const unsigned int *mask, const size_t *offset, const size_t offset_new) {
+char *logger_write_chunk_header(char *buff, const unsigned int *mask, const size_t *offset, const size_t offset_new) {
   memcpy(buff, mask, logger_size_mask);
   buff += logger_size_mask;
   
@@ -129,7 +129,7 @@ void logger_write_general_data(struct dump *d, struct logger_const *log, size_t
  *
  * @return The size of the logger message in bytes.
  */
-int logger_size(unsigned int mask) {
+int logger_compute_chunk_size(unsigned int mask) {
 
   /* Start with 8 bytes for the header. */
   int size = 8;
@@ -208,7 +208,7 @@ void logger_log_part(const struct part *p, const unsigned int mask, size_t *offs
     error("You should not log particles as timestamps.");
 
   /* Start by computing the size of the message. */
-  const int size = logger_buffer_size(mask);
+  const int size = logger_compute_chunk_size(mask);
 
   /* Allocate a chunk of memory in the dump of the right size. */
   size_t offset_new;
@@ -289,7 +289,7 @@ void logger_log_gpart(const struct gpart *p, const unsigned int mask, size_t *of
     error("Can't log SPH quantities for gparts.");
 
   /* Start by computing the size of the message. */
-  const int size = logger_buffer_size(mask);
+  const int size = logger_compute_chunk_size(mask);
 
   /* Allocate a chunk of memory in the dump of the right size. */
   size_t offset_new;
@@ -338,7 +338,7 @@ void logger_log_gpart(const struct gpart *p, const unsigned int mask, size_t *of
 void logger_log_timestamp(integertime_t timestamp, size_t *offset,
                           struct dump *dump) {
   /* Start by computing the size of the message. */
-  const int size = logger_buffer_size(logger_mask_timestamp);
+  const int size = logger_compute_chunk_size(logger_mask_timestamp);
 
   /* Allocate a chunk of memory in the dump of the right size. */
   size_t offset_new;
diff --git a/src/logger.h b/src/logger.h
index f81a833d505fd3970b0210ab955b94beb4e7034f..ecdc617643e2e7c271e135bf6cbf901a430c9a69 100644
--- a/src/logger.h
+++ b/src/logger.h
@@ -119,7 +119,7 @@ enum logger_datatype {
 extern const unsigned int logger_data_size[];
 
 /* Function prototypes. */
-int logger_size(unsigned int mask);
+int logger_compute_chunk_size(unsigned int mask);
 void logger_log_all(struct part *p,
 		    const long long Np, struct dump *dump);
 void logger_log_part(const struct part *p, const unsigned int mask, size_t *offset,
@@ -135,7 +135,7 @@ int logger_read_timestamp(unsigned long long int *t, size_t *offset,
 void logger_write_file_header(struct dump *dump, struct engine* e);
 void logger_const_init(struct logger_const* log_const);
 void logger_const_free(struct logger_const* log_const);
-void logger_ensure_size(size_t total_nr_parts, size_t logger_size);
+void logger_ensure_size(size_t total_nr_parts, size_t logger_buffer_size);
 
 #endif /* WITH_LOGGER */
 
diff --git a/src/logger_io.c b/src/logger_io.c
index 7b9b0500eb0f738ab43a9782cfb9a5e188e4d71c..e877e7533091f41668b2fc02dd2f05d74ae127fe 100644
--- a/src/logger_io.c
+++ b/src/logger_io.c
@@ -21,7 +21,7 @@
 /* Config parameters. */
 #include "../config.h"
 
-#if defined(HAVE_HDF5) && !defined(WITH_MPI) && defined(WITH_LOGGER)
+#ifdef WITH_LOGGER
 
 /* Some standard headers. */
 #include <hdf5.h>
@@ -47,771 +47,14 @@
 #include "hydro_properties.h"
 #include "io_properties.h"
 #include "kernel_hydro.h"
+#include "parallel_io.h"
 #include "part.h"
+#include "serial_io.h"
+#include "single_io.h"
 #include "stars_io.h"
 #include "units.h"
 #include "xmf.h"
 
-/*-----------------------------------------------------------------------------
- * Routines reading an IC file
- *-----------------------------------------------------------------------------*/
-
-/**
- * @brief Reads a data array from a given HDF5 group.
- *
- * @param h_grp The group from which to read.
- * @param prop The #io_props of the field to read
- * @param N The number of particles.
- * @param internal_units The #unit_system used internally
- * @param ic_units The #unit_system used in the ICs
- *
- * @todo A better version using HDF5 hyper-slabs to read the file directly into
- * the part array will be written once the structures have been stabilized.
- */
-void readArray(hid_t h_grp, const struct io_props prop, size_t N,
-               const struct unit_system* internal_units,
-               const struct unit_system* ic_units) {
-
-  const size_t typeSize = io_sizeof_type(prop.type);
-  const size_t copySize = typeSize * prop.dimension;
-  const size_t num_elements = N * prop.dimension;
-
-  /* Check whether the dataspace exists or not */
-  const htri_t exist = H5Lexists(h_grp, prop.name, 0);
-  if (exist < 0) {
-    error("Error while checking the existence of data set '%s'.", prop.name);
-  } else if (exist == 0) {
-    if (prop.importance == COMPULSORY) {
-      error("Compulsory data set '%s' not present in the file.", prop.name);
-    } else {
-      /* message("Optional data set '%s' not present. Zeroing this particle
-       * prop...", name);	   */
-
-      for (size_t i = 0; i < N; ++i)
-        memset(prop.field + i * prop.partSize, 0, copySize);
-
-      return;
-    }
-  }
-
-  /* message("Reading %s '%s' array...", */
-  /*         prop.importance == COMPULSORY ? "compulsory" : "optional  ", */
-  /*         prop.name); */
-
-  /* Open data space */
-  const hid_t h_data = H5Dopen(h_grp, prop.name, H5P_DEFAULT);
-  if (h_data < 0) {
-    error("Error while opening data space '%s'.", prop.name);
-  }
-
-  /* Check data type */
-  const hid_t h_type = H5Dget_type(h_data);
-  if (h_type < 0) error("Unable to retrieve data type from the file");
-  // if (!H5Tequal(h_type, hdf5_type(type)))
-  //  error("Non-matching types between the code and the file");
-
-  /* Allocate temporary buffer */
-  void* temp = malloc(num_elements * typeSize);
-  if (temp == NULL) error("Unable to allocate memory for temporary buffer");
-
-  /* Read HDF5 dataspace in temporary buffer */
-  /* Dirty version that happens to work for vectors but should be improved */
-  /* Using HDF5 dataspaces would be better */
-  const hid_t h_err = H5Dread(h_data, io_hdf5_type(prop.type), H5S_ALL, H5S_ALL,
-                              H5P_DEFAULT, temp);
-  if (h_err < 0) {
-    error("Error while reading data array '%s'.", prop.name);
-  }
-
-  /* Unit conversion if necessary */
-  const double factor =
-      units_conversion_factor(ic_units, internal_units, prop.units);
-  if (factor != 1. && exist != 0) {
-
-    /* message("Converting ! factor=%e", factor); */
-
-    if (io_is_double_precision(prop.type)) {
-      double* temp_d = temp;
-      for (size_t i = 0; i < num_elements; ++i) temp_d[i] *= factor;
-    } else {
-      float* temp_f = temp;
-      for (size_t i = 0; i < num_elements; ++i) temp_f[i] *= factor;
-    }
-  }
-
-  /* Copy temporary buffer to particle data */
-  char* temp_c = temp;
-  for (size_t i = 0; i < N; ++i)
-    memcpy(prop.field + i * prop.partSize, &temp_c[i * copySize], copySize);
-
-  /* Free and close everything */
-  free(temp);
-  H5Tclose(h_type);
-  H5Dclose(h_data);
-}
-
-/*-----------------------------------------------------------------------------
- * Routines writing an output file
- *-----------------------------------------------------------------------------*/
-
-/**
- * @brief Writes a data array in given HDF5 group.
- *
- * @param e The #engine we are writing from.
- * @param grp The group in which to write.
- * @param fileName The name of the file in which the data is written
- * @param xmfFile The FILE used to write the XMF description
- * @param partTypeGroupName The name of the group containing the particles in
- * the HDF5 file.
- * @param props The #io_props of the field to read
- * @param N The number of particles to write.
- * @param internal_units The #unit_system used internally
- * @param snapshot_units The #unit_system used in the snapshots
- *
- * @todo A better version using HDF5 hyper-slabs to write the file directly from
- * the part array will be written once the structures have been stabilized.
- */
-void writeArray(const struct engine* e, hid_t grp, char* fileName,
-                FILE* xmfFile, char* partTypeGroupName,
-                const struct io_props props, size_t N,
-                const struct unit_system* internal_units,
-                const struct unit_system* snapshot_units) {
-
-  const size_t typeSize = io_sizeof_type(props.type);
-  const size_t num_elements = N * props.dimension;
-
-  /* message("Writing '%s' array...", props.name); */
-
-  /* Allocate temporary buffer */
-  void* temp = NULL;
-  if (posix_memalign((void**)&temp, IO_BUFFER_ALIGNMENT,
-                     num_elements * typeSize) != 0)
-    error("Unable to allocate temporary i/o buffer");
-
-  /* Copy the particle data to the temporary buffer */
-  io_copy_temp_buffer(temp, e, props, N, internal_units, snapshot_units);
-
-  /* Create data space */
-  const hid_t h_space = H5Screate(H5S_SIMPLE);
-  int rank;
-  hsize_t shape[2];
-  hsize_t chunk_shape[2];
-  if (h_space < 0) {
-    error("Error while creating data space for field '%s'.", props.name);
-  }
-
-  if (props.dimension > 1) {
-    rank = 2;
-    shape[0] = N;
-    shape[1] = props.dimension;
-    chunk_shape[0] = 1 << 16; /* Just a guess...*/
-    chunk_shape[1] = props.dimension;
-  } else {
-    rank = 1;
-    shape[0] = N;
-    shape[1] = 0;
-    chunk_shape[0] = 1 << 16; /* Just a guess...*/
-    chunk_shape[1] = 0;
-  }
-
-  /* Make sure the chunks are not larger than the dataset */
-  if (chunk_shape[0] > N) chunk_shape[0] = N;
-
-  /* Change shape of data space */
-  hid_t h_err = H5Sset_extent_simple(h_space, rank, shape, NULL);
-  if (h_err < 0) {
-    error("Error while changing data space shape for field '%s'.", props.name);
-  }
-
-  /* Dataset properties */
-  const hid_t h_prop = H5Pcreate(H5P_DATASET_CREATE);
-
-  /* Set chunk size */
-  h_err = H5Pset_chunk(h_prop, rank, chunk_shape);
-  if (h_err < 0) {
-    error("Error while setting chunk size (%llu, %llu) for field '%s'.",
-          chunk_shape[0], chunk_shape[1], props.name);
-  }
-
-  /* Impose data compression */
-  if (e->snapshotCompression > 0) {
-    h_err = H5Pset_deflate(h_prop, e->snapshotCompression);
-    if (h_err < 0) {
-      error("Error while setting compression options for field '%s'.",
-            props.name);
-    }
-  }
-
-  /* Create dataset */
-  const hid_t h_data = H5Dcreate(grp, props.name, io_hdf5_type(props.type),
-                                 h_space, H5P_DEFAULT, h_prop, H5P_DEFAULT);
-  if (h_data < 0) {
-    error("Error while creating dataspace '%s'.", props.name);
-  }
-
-  /* Write temporary buffer to HDF5 dataspace */
-  h_err = H5Dwrite(h_data, io_hdf5_type(props.type), h_space, H5S_ALL,
-                   H5P_DEFAULT, temp);
-  if (h_err < 0) {
-    error("Error while writing data array '%s'.", props.name);
-  }
-
-  /* Write XMF description for this data set */
-  if (xmfFile != NULL)
-    xmf_write_line(xmfFile, fileName, partTypeGroupName, props.name, N,
-		   props.dimension, props.type);
-
-  /* Write unit conversion factors for this data set */
-  char buffer[FIELD_BUFFER_SIZE];
-  units_cgs_conversion_string(buffer, snapshot_units, props.units);
-  io_write_attribute_d(
-      h_data, "CGS conversion factor",
-      units_cgs_conversion_factor(snapshot_units, props.units));
-  io_write_attribute_f(h_data, "h-scale exponent",
-                       units_h_factor(snapshot_units, props.units));
-  io_write_attribute_f(h_data, "a-scale exponent",
-                       units_a_factor(snapshot_units, props.units));
-  io_write_attribute_s(h_data, "Conversion factor", buffer);
-
-  /* Free and close everything */
-  free(temp);
-  H5Pclose(h_prop);
-  H5Dclose(h_data);
-  H5Sclose(h_space);
-}
-
-/**
- * @brief Reads an HDF5 initial condition file (GADGET-3 type)
- *
- * @param fileName The file to read.
- * @param internal_units The system units used internally
- * @param dim (output) The dimension of the volume.
- * @param parts (output) Array of #part particles.
- * @param gparts (output) Array of #gpart particles.
- * @param sparts (output) Array of #spart particles.
- * @param Ngas (output) number of Gas particles read.
- * @param Ngparts (output) The number of #gpart read.
- * @param Nstars (output) The number of #spart read.
- * @param periodic (output) 1 if the volume is periodic, 0 if not.
- * @param flag_entropy (output) 1 if the ICs contained Entropy in the
- * InternalEnergy field
- * @param with_hydro Are we reading gas particles ?
- * @param with_gravity Are we reading/creating #gpart arrays ?
- * @param with_stars Are we reading star particles ?
- * @param dry_run If 1, don't read the particle. Only allocates the arrays.
- *
- * Opens the HDF5 file fileName and reads the particles contained
- * in the parts array. N is the returned number of particles found
- * in the file.
- *
- * @warning Can not read snapshot distributed over more than 1 file !!!
- * @todo Read snapshots distributed in more than one file.
- *
- */
-void read_ic_single(char* fileName, const struct unit_system* internal_units,
-                    double dim[3], struct part** parts, struct gpart** gparts,
-                    struct spart** sparts, size_t* Ngas, size_t* Ngparts,
-                    size_t* Nstars, int* periodic, int* flag_entropy,
-                    int with_hydro, int with_gravity, int with_stars,
-                    int n_threads, int dry_run) {
-
-  hid_t h_file = 0, h_grp = 0;
-  /* GADGET has only cubic boxes (in cosmological mode) */
-  double boxSize[3] = {0.0, -1.0, -1.0};
-  /* GADGET has 6 particle types. We only keep the type 0 & 1 for now...*/
-  int numParticles[swift_type_count] = {0};
-  int numParticles_highWord[swift_type_count] = {0};
-  size_t N[swift_type_count] = {0};
-  int dimension = 3; /* Assume 3D if nothing is specified */
-  size_t Ndm = 0;
-
-  /* Open file */
-  /* message("Opening file '%s' as IC.", fileName); */
-  h_file = H5Fopen(fileName, H5F_ACC_RDONLY, H5P_DEFAULT);
-  if (h_file < 0) {
-    error("Error while opening file '%s'.", fileName);
-  }
-
-  /* Open header to read simulation properties */
-  /* message("Reading runtime parameters..."); */
-  h_grp = H5Gopen(h_file, "/RuntimePars", H5P_DEFAULT);
-  if (h_grp < 0) error("Error while opening runtime parameters\n");
-
-  /* Read the relevant information */
-  io_read_attribute(h_grp, "PeriodicBoundariesOn", INT, periodic);
-
-  /* Close runtime parameters */
-  H5Gclose(h_grp);
-
-  /* Open header to read simulation properties */
-  /* message("Reading file header..."); */
-  h_grp = H5Gopen(h_file, "/Header", H5P_DEFAULT);
-  if (h_grp < 0) error("Error while opening file header\n");
-
-  /* Check the dimensionality of the ICs (if the info exists) */
-  const hid_t hid_dim = H5Aexists(h_grp, "Dimension");
-  if (hid_dim < 0)
-    error("Error while testing existance of 'Dimension' attribute");
-  if (hid_dim > 0) io_read_attribute(h_grp, "Dimension", INT, &dimension);
-  if (dimension != hydro_dimension)
-    error("ICs dimensionality (%dD) does not match code dimensionality (%dD)",
-          dimension, (int)hydro_dimension);
-
-  /* Read the relevant information and print status */
-  int flag_entropy_temp[6];
-  io_read_attribute(h_grp, "Flag_Entropy_ICs", INT, flag_entropy_temp);
-  *flag_entropy = flag_entropy_temp[0];
-  io_read_attribute(h_grp, "BoxSize", DOUBLE, boxSize);
-  io_read_attribute(h_grp, "NumPart_Total", UINT, numParticles);
-  io_read_attribute(h_grp, "NumPart_Total_HighWord", UINT,
-                    numParticles_highWord);
-
-  for (int ptype = 0; ptype < swift_type_count; ++ptype)
-    N[ptype] = ((long long)numParticles[ptype]) +
-               ((long long)numParticles_highWord[ptype] << 32);
-
-  /* Get the box size if not cubic */
-  dim[0] = boxSize[0];
-  dim[1] = (boxSize[1] < 0) ? boxSize[0] : boxSize[1];
-  dim[2] = (boxSize[2] < 0) ? boxSize[0] : boxSize[2];
-
-  /* Change box size in the 1D and 2D case */
-  if (hydro_dimension == 2)
-    dim[2] = min(dim[0], dim[1]);
-  else if (hydro_dimension == 1)
-    dim[2] = dim[1] = dim[0];
-
-  /* message("Found %d particles in a %speriodic box of size [%f %f %f].",  */
-  /* 	  *N, (periodic ? "": "non-"), dim[0], dim[1], dim[2]);  */
-
-  /* Close header */
-  H5Gclose(h_grp);
-
-  /* Read the unit system used in the ICs */
-  struct unit_system* ic_units = malloc(sizeof(struct unit_system));
-  if (ic_units == NULL) error("Unable to allocate memory for IC unit system");
-  io_read_unit_system(h_file, ic_units, 0);
-
-  /* Tell the user if a conversion will be needed */
-  if (units_are_equal(ic_units, internal_units)) {
-
-    message("IC and internal units match. No conversion needed.");
-
-  } else {
-
-    message("Conversion needed from:");
-    message("(ICs) Unit system: U_M =      %e g.", ic_units->UnitMass_in_cgs);
-    message("(ICs) Unit system: U_L =      %e cm.",
-            ic_units->UnitLength_in_cgs);
-    message("(ICs) Unit system: U_t =      %e s.", ic_units->UnitTime_in_cgs);
-    message("(ICs) Unit system: U_I =      %e A.",
-            ic_units->UnitCurrent_in_cgs);
-    message("(ICs) Unit system: U_T =      %e K.",
-            ic_units->UnitTemperature_in_cgs);
-    message("to:");
-    message("(internal) Unit system: U_M = %e g.",
-            internal_units->UnitMass_in_cgs);
-    message("(internal) Unit system: U_L = %e cm.",
-            internal_units->UnitLength_in_cgs);
-    message("(internal) Unit system: U_t = %e s.",
-            internal_units->UnitTime_in_cgs);
-    message("(internal) Unit system: U_I = %e A.",
-            internal_units->UnitCurrent_in_cgs);
-    message("(internal) Unit system: U_T = %e K.",
-            internal_units->UnitTemperature_in_cgs);
-  }
-
-  /* Convert the dimensions of the box */
-  for (int j = 0; j < 3; j++)
-    dim[j] *=
-        units_conversion_factor(ic_units, internal_units, UNIT_CONV_LENGTH);
-
-  /* Allocate memory to store SPH particles */
-  if (with_hydro) {
-    *Ngas = N[swift_type_gas];
-    if (posix_memalign((void*)parts, part_align, *Ngas * sizeof(struct part)) !=
-        0)
-      error("Error while allocating memory for SPH particles");
-    bzero(*parts, *Ngas * sizeof(struct part));
-  }
-
-  /* Allocate memory to store star particles */
-  if (with_stars) {
-    *Nstars = N[swift_type_star];
-    if (posix_memalign((void*)sparts, spart_align,
-                       *Nstars * sizeof(struct spart)) != 0)
-      error("Error while allocating memory for star particles");
-    bzero(*sparts, *Nstars * sizeof(struct spart));
-  }
-
-  /* Allocate memory to store all gravity particles */
-  if (with_gravity) {
-    Ndm = N[swift_type_dark_matter];
-    *Ngparts = (with_hydro ? N[swift_type_gas] : 0) +
-               N[swift_type_dark_matter] +
-               (with_stars ? N[swift_type_star] : 0);
-    if (posix_memalign((void*)gparts, gpart_align,
-                       *Ngparts * sizeof(struct gpart)) != 0)
-      error("Error while allocating memory for gravity particles");
-    bzero(*gparts, *Ngparts * sizeof(struct gpart));
-  }
-
-  /* message("Allocated %8.2f MB for particles.", *N * sizeof(struct part) /
-   * (1024.*1024.)); */
-
-  /* message("BoxSize = %lf", dim[0]); */
-  /* message("NumPart = [%zd, %zd] Total = %zd", *Ngas, Ndm, *Ngparts); */
-
-  /* Loop over all particle types */
-  for (int ptype = 0; ptype < swift_type_count; ptype++) {
-
-    /* Don't do anything if no particle of this kind */
-    if (N[ptype] == 0) continue;
-
-    /* Open the particle group in the file */
-    char partTypeGroupName[PARTICLE_GROUP_BUFFER_SIZE];
-    snprintf(partTypeGroupName, PARTICLE_GROUP_BUFFER_SIZE, "/PartType%d",
-             ptype);
-    h_grp = H5Gopen(h_file, partTypeGroupName, H5P_DEFAULT);
-    if (h_grp < 0) {
-      error("Error while opening particle group %s.", partTypeGroupName);
-    }
-
-    int num_fields = 0;
-    struct io_props list[100];
-    size_t Nparticles = 0;
-
-    /* Read particle fields into the structure */
-    switch (ptype) {
-
-      case swift_type_gas:
-        if (with_hydro) {
-          Nparticles = *Ngas;
-          hydro_read_particles(*parts, list, &num_fields);
-          num_fields += chemistry_read_particles(*parts, list + num_fields);
-        }
-        break;
-
-      case swift_type_dark_matter:
-        if (with_gravity) {
-          Nparticles = Ndm;
-          darkmatter_read_particles(*gparts, list, &num_fields);
-        }
-        break;
-
-      case swift_type_star:
-        if (with_stars) {
-          Nparticles = *Nstars;
-          star_read_particles(*sparts, list, &num_fields);
-        }
-        break;
-
-      default:
-        message("Particle Type %d not yet supported. Particles ignored", ptype);
-    }
-
-    /* Read everything */
-    if (!dry_run)
-      for (int i = 0; i < num_fields; ++i)
-        readArray(h_grp, list[i], Nparticles, internal_units, ic_units);
-
-    /* Close particle group */
-    H5Gclose(h_grp);
-  }
-
-  /* Duplicate the parts for gravity */
-  if (!dry_run && with_gravity) {
-
-    /* Let's initialise a bit of thread parallelism here */
-    struct threadpool tp;
-    threadpool_init(&tp, n_threads);
-
-    /* Prepare the DM particles */
-    io_prepare_dm_gparts(&tp, *gparts, Ndm);
-
-    /* Duplicate the hydro particles into gparts */
-    if (with_hydro) io_duplicate_hydro_gparts(&tp, *parts, *gparts, *Ngas, Ndm);
-
-    /* Duplicate the star particles into gparts */
-    if (with_stars)
-      io_duplicate_star_gparts(&tp, *sparts, *gparts, *Nstars, Ndm + *Ngas);
-
-    threadpool_clean(&tp);
-  }
-
-  /* message("Done Reading particles..."); */
-
-  /* Clean up */
-  free(ic_units);
-
-  /* Close file */
-  H5Fclose(h_file);
-}
-
-/**
- * @brief Writes an HDF5 output file (GADGET-3 type) with its XMF descriptor
- *
- * @param e The engine containing all the system.
- * @param baseName The common part of the snapshot file name.
- * @param internal_units The #unit_system used internally
- * @param snapshot_units The #unit_system used in the snapshots
- *
- * Creates an HDF5 output file and writes the particles contained
- * in the engine. If such a file already exists, it is erased and replaced
- * by the new one.
- * The companion XMF file is also updated accordingly.
- *
- * Calls #error() if an error occurs.
- *
- */
-void write_output_single(struct engine* e, const char* baseName,
-                         const struct unit_system* internal_units,
-                         const struct unit_system* snapshot_units) {
-
-  hid_t h_file = 0, h_grp = 0;
-  const size_t Ngas = e->s->nr_parts;
-  const size_t Nstars = e->s->nr_sparts;
-  const size_t Ntot = e->s->nr_gparts;
-  int periodic = e->s->periodic;
-  int numFiles = 1;
-  struct part* parts = e->s->parts;
-  struct gpart* gparts = e->s->gparts;
-  struct gpart* dmparts = NULL;
-  struct spart* sparts = e->s->sparts;
-  static int outputCount = 0;
-
-  /* Number of unassociated gparts */
-  const size_t Ndm = Ntot > 0 ? Ntot - (Ngas + Nstars) : 0;
-
-  long long N_total[swift_type_count] = {Ngas, Ndm, 0, 0, Nstars, 0};
-
-  /* File name */
-  char fileName[FILENAME_BUFFER_SIZE];
-  snprintf(fileName, FILENAME_BUFFER_SIZE, "%s_%04i.hdf5", baseName,
-           outputCount);
-
-  /* First time, we need to create the XMF file */
-  if (outputCount == 0) xmf_create_file(baseName);
-
-  /* Prepare the XMF file for the new entry */
-  FILE* xmfFile = 0;
-  xmfFile = xmf_prepare_file(baseName);
-
-  /* Write the part corresponding to this specific output */
-  xmf_write_outputheader(xmfFile, fileName, e->time);
-
-  /* Open file */
-  /* message("Opening file '%s'.", fileName); */
-  h_file = H5Fcreate(fileName, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
-  if (h_file < 0) {
-    error("Error while opening file '%s'.", fileName);
-  }
-
-  /* Open header to write simulation properties */
-  /* message("Writing runtime parameters..."); */
-  h_grp =
-      H5Gcreate(h_file, "/RuntimePars", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
-  if (h_grp < 0) error("Error while creating runtime parameters group\n");
-
-  /* Write the relevant information */
-  io_write_attribute(h_grp, "PeriodicBoundariesOn", INT, &periodic, 1);
-  int index = 0;
-  io_write_attribute(h_grp, "IsIndexFile", INT, &index, 1);
-
-  /* Close runtime parameters */
-  H5Gclose(h_grp);
-
-  /* Open header to write simulation properties */
-  /* message("Writing file header..."); */
-  h_grp = H5Gcreate(h_file, "/Header", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
-  if (h_grp < 0) error("Error while creating file header\n");
-
-  /* Print the relevant information and print status */
-  io_write_attribute(h_grp, "BoxSize", DOUBLE, e->s->dim, 3);
-  double dblTime = e->time;
-  io_write_attribute(h_grp, "Time", DOUBLE, &dblTime, 1);
-  int dimension = (int)hydro_dimension;
-  io_write_attribute(h_grp, "Dimension", INT, &dimension, 1);
-
-  /* GADGET-2 legacy values */
-  /* Number of particles of each type */
-  unsigned int numParticles[swift_type_count] = {0};
-  unsigned int numParticlesHighWord[swift_type_count] = {0};
-  for (int ptype = 0; ptype < swift_type_count; ++ptype) {
-    numParticles[ptype] = (unsigned int)N_total[ptype];
-    numParticlesHighWord[ptype] = (unsigned int)(N_total[ptype] >> 32);
-  }
-  io_write_attribute(h_grp, "NumPart_ThisFile", LONGLONG, N_total,
-                     swift_type_count);
-  io_write_attribute(h_grp, "NumPart_Total", UINT, numParticles,
-                     swift_type_count);
-  io_write_attribute(h_grp, "NumPart_Total_HighWord", UINT,
-                     numParticlesHighWord, swift_type_count);
-  double MassTable[swift_type_count] = {0};
-  io_write_attribute(h_grp, "MassTable", DOUBLE, MassTable, swift_type_count);
-  unsigned int flagEntropy[swift_type_count] = {0};
-  flagEntropy[0] = writeEntropyFlag();
-  io_write_attribute(h_grp, "Flag_Entropy_ICs", UINT, flagEntropy,
-                     swift_type_count);
-  io_write_attribute(h_grp, "NumFilesPerSnapshot", INT, &numFiles, 1);
-
-  /* Close header */
-  H5Gclose(h_grp);
-
-  /* Print the code version */
-  io_write_code_description(h_file);
-
-  /* Print the SPH parameters */
-  if (e->policy & engine_policy_hydro) {
-    h_grp = H5Gcreate(h_file, "/HydroScheme", H5P_DEFAULT, H5P_DEFAULT,
-                      H5P_DEFAULT);
-    if (h_grp < 0) error("Error while creating SPH group");
-    hydro_props_print_snapshot(h_grp, e->hydro_properties);
-    hydro_write_flavour(h_grp);
-    H5Gclose(h_grp);
-  }
-
-  /* Print the gravity parameters */
-  if (e->policy & engine_policy_self_gravity) {
-    h_grp = H5Gcreate(h_file, "/GravityScheme", H5P_DEFAULT, H5P_DEFAULT,
-                      H5P_DEFAULT);
-    if (h_grp < 0) error("Error while creating gravity group");
-    gravity_props_print_snapshot(h_grp, e->gravity_properties);
-    H5Gclose(h_grp);
-  }
-
-  /* Print the runtime parameters */
-  h_grp =
-      H5Gcreate(h_file, "/Parameters", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
-  if (h_grp < 0) error("Error while creating parameters group");
-  parser_write_params_to_hdf5(e->parameter_file, h_grp);
-  H5Gclose(h_grp);
-
-  /* Print the system of Units used in the spashot */
-  io_write_unit_system(h_file, snapshot_units, "Units");
-
-  /* Print the system of Units used internally */
-  io_write_unit_system(h_file, internal_units, "InternalCodeUnits");
-
-  /* Tell the user if a conversion will be needed */
-  if (e->verbose) {
-    if (units_are_equal(snapshot_units, internal_units)) {
-
-      message("Snapshot and internal units match. No conversion needed.");
-
-    } else {
-
-      message("Conversion needed from:");
-      message("(Snapshot) Unit system: U_M =      %e g.",
-              snapshot_units->UnitMass_in_cgs);
-      message("(Snapshot) Unit system: U_L =      %e cm.",
-              snapshot_units->UnitLength_in_cgs);
-      message("(Snapshot) Unit system: U_t =      %e s.",
-              snapshot_units->UnitTime_in_cgs);
-      message("(Snapshot) Unit system: U_I =      %e A.",
-              snapshot_units->UnitCurrent_in_cgs);
-      message("(Snapshot) Unit system: U_T =      %e K.",
-              snapshot_units->UnitTemperature_in_cgs);
-      message("to:");
-      message("(internal) Unit system: U_M = %e g.",
-              internal_units->UnitMass_in_cgs);
-      message("(internal) Unit system: U_L = %e cm.",
-              internal_units->UnitLength_in_cgs);
-      message("(internal) Unit system: U_t = %e s.",
-              internal_units->UnitTime_in_cgs);
-      message("(internal) Unit system: U_I = %e A.",
-              internal_units->UnitCurrent_in_cgs);
-      message("(internal) Unit system: U_T = %e K.",
-              internal_units->UnitTemperature_in_cgs);
-    }
-  }
-
-  /* Loop over all particle types */
-  for (int ptype = 0; ptype < swift_type_count; ptype++) {
-
-    /* Don't do anything if no particle of this kind */
-    if (numParticles[ptype] == 0) continue;
-
-    /* Add the global information for that particle type to the XMF meta-file */
-    xmf_write_groupheader(xmfFile, fileName, numParticles[ptype],
-                          (enum part_type)ptype);
-
-    /* Open the particle group in the file */
-    char partTypeGroupName[PARTICLE_GROUP_BUFFER_SIZE];
-    snprintf(partTypeGroupName, PARTICLE_GROUP_BUFFER_SIZE, "/PartType%d",
-             ptype);
-    h_grp = H5Gcreate(h_file, partTypeGroupName, H5P_DEFAULT, H5P_DEFAULT,
-                      H5P_DEFAULT);
-    if (h_grp < 0) {
-      error("Error while creating particle group.\n");
-    }
-
-    int num_fields = 0;
-    struct io_props list[100];
-    size_t N = 0;
-
-    /* Write particle fields from the particle structure */
-    switch (ptype) {
-
-      case swift_type_gas:
-        N = Ngas;
-        hydro_write_particles(parts, list, &num_fields);
-        break;
-
-      case swift_type_dark_matter:
-        /* Allocate temporary array */
-        if (posix_memalign((void*)&dmparts, gpart_align,
-                           Ndm * sizeof(struct gpart)) != 0)
-          error("Error while allocating temporart memory for DM particles");
-        bzero(dmparts, Ndm * sizeof(struct gpart));
-
-        /* Collect the DM particles from gpart */
-        io_collect_dm_gparts(gparts, Ntot, dmparts, Ndm);
-
-        /* Write DM particles */
-        N = Ndm;
-        darkmatter_write_particles(dmparts, list, &num_fields);
-        break;
-
-      case swift_type_star:
-        N = Nstars;
-        star_write_particles(sparts, list, &num_fields);
-        break;
-
-      default:
-        error("Particle Type %d not yet supported. Aborting", ptype);
-    }
-
-    /* Write everything */
-    for (int i = 0; i < num_fields; ++i)
-      writeArray(e, h_grp, fileName, xmfFile, partTypeGroupName, list[i], N,
-                 internal_units, snapshot_units);
-
-    /* Free temporary array */
-    if (dmparts) {
-      free(dmparts);
-      dmparts = NULL;
-    }
-
-    /* Close particle group */
-    H5Gclose(h_grp);
-
-    /* Close this particle group in the XMF file as well */
-    xmf_write_groupfooter(xmfFile, (enum part_type)ptype);
-  }
-
-  /* Write LXMF file descriptor */
-  xmf_write_outputfooter(xmfFile, outputCount, e->time);
-
-  /* message("Done writing particles..."); */
-
-  /* Close file */
-  H5Fclose(h_file);
-
-  ++outputCount;
-}
-
-
 /**
  * @brief Writes an HDF5 index file
  *
diff --git a/src/logger_io.h b/src/logger_io.h
index c4f245395f38c235c1f1249272c835658a486a7c..208166ac6d6f2e883f3006659a6d3de08908c593 100644
--- a/src/logger_io.h
+++ b/src/logger_io.h
@@ -22,7 +22,7 @@
 /* Config parameters. */
 #include "../config.h"
 
-#if defined(HAVE_HDF5) && !defined(WITH_MPI) && defined(WITH_LOGGER)
+#ifdef WITH_LOGGER
 
 /* Includes. */
 #include "engine.h"
diff --git a/src/parallel_io.c b/src/parallel_io.c
index 44149480b572ec41c4c85b6957156a8ae75757ba..e1a9d2c068040192654a560508b0ede7544f1b3e 100644
--- a/src/parallel_io.c
+++ b/src/parallel_io.c
@@ -21,7 +21,7 @@
 /* Config parameters. */
 #include "../config.h"
 
-#if defined(HAVE_HDF5) && defined(WITH_MPI) && defined(HAVE_PARALLEL_HDF5) && !defined(WITH_LOGGER)
+#if defined(HAVE_HDF5) && defined(WITH_MPI) && defined(HAVE_PARALLEL_HDF5)
 
 /* Some standard headers. */
 #include <hdf5.h>
diff --git a/src/parallel_io.h b/src/parallel_io.h
index 1805d9c4a99fdf3bb55959fbb238aeffbee18615..2de83265f3ff964ae4808da14a8db6aff635cd3c 100644
--- a/src/parallel_io.h
+++ b/src/parallel_io.h
@@ -46,6 +46,13 @@ void write_output_parallel(struct engine* e, const char* baseName,
                            const struct unit_system* snapshot_units,
                            int mpi_rank, int mpi_size, MPI_Comm comm,
                            MPI_Info info);
+
+void writeArray(struct engine* e, hid_t grp, char* fileName, FILE* xmfFile,
+                char* partTypeGroupName, struct io_props props, size_t N,
+                long long N_total, int mpi_rank, long long offset,
+                const struct unit_system* internal_units,
+                const struct unit_system* snapshot_units);
+
 #endif
 
 #endif /* SWIFT_PARALLEL_IO_H */
diff --git a/src/serial_io.c b/src/serial_io.c
index 042c60cba129db374565782585821b605f9f3f20..8e63f9b72ebe0df5881b1dbf6b43631f9ed79a0e 100644
--- a/src/serial_io.c
+++ b/src/serial_io.c
@@ -21,7 +21,7 @@
 /* Config parameters. */
 #include "../config.h"
 
-#if defined(HAVE_HDF5) && defined(WITH_MPI) && !defined(HAVE_PARALLEL_HDF5) && !defined(WITH_LOGGER)
+#if defined(HAVE_HDF5) && defined(WITH_MPI) && !defined(HAVE_PARALLEL_HDF5)
 
 /* Some standard headers. */
 #include <hdf5.h>
diff --git a/src/serial_io.h b/src/serial_io.h
index f6280085e2ac294301017768126eec8c8f2c3d0e..d46e9687546d93af9c99339cdbe1d7dd72c87116 100644
--- a/src/serial_io.h
+++ b/src/serial_io.h
@@ -48,6 +48,12 @@ void write_output_serial(struct engine* e, const char* baseName,
                          const struct unit_system* snapshot_units, int mpi_rank,
                          int mpi_size, MPI_Comm comm, MPI_Info info);
 
+void writeArray(const struct engine* e, hid_t grp, char* fileName,
+                FILE* xmfFile, char* partTypeGroupName,
+                const struct io_props props, size_t N, long long N_total,
+                int mpi_rank, long long offset,
+                const struct unit_system* internal_units,
+                const struct unit_system* snapshot_units);
 #endif
 
 #endif /* SWIFT_SERIAL_IO_H */
diff --git a/src/single_io.c b/src/single_io.c
index a8d208b267384a9eb9ce59a5f17644828bd31d2c..d3c46a58bd375a7412774c36e86ce2b36173f333 100644
--- a/src/single_io.c
+++ b/src/single_io.c
@@ -21,7 +21,7 @@
 /* Config parameters. */
 #include "../config.h"
 
-#if defined(HAVE_HDF5) && !defined(WITH_MPI) && !defined(WITH_LOGGER)
+#if defined(HAVE_HDF5) && !defined(WITH_MPI)
 
 /* Some standard headers. */
 #include <hdf5.h>
diff --git a/src/single_io.h b/src/single_io.h
index aef5d1c8b667d4694981031cb691bbceb249950c..390a3aac149a9ab1c31cc24769c1d7a8d17e48e2 100644
--- a/src/single_io.h
+++ b/src/single_io.h
@@ -26,6 +26,7 @@
 
 /* Includes. */
 #include "engine.h"
+#include "io_properties.h"
 #include "part.h"
 #include "units.h"
 
@@ -46,6 +47,10 @@ void write_index_single(struct engine* e, const char* baseName,
 			const struct unit_system* internal_units,
 			const struct unit_system* snapshot_units);
 
-#endif /* HAVE_HDF5 && !WITH_MPI */
+void writeArray(const struct engine* e, hid_t grp, char* fileName,
+                FILE* xmfFile, char* partTypeGroupName,
+                const struct io_props props, size_t N,
+                const struct unit_system* internal_units,
+                const struct unit_system* snapshot_units);
 
 #endif /* SWIFT_SINGLE_IO_H */