diff --git a/source/adios2/engine/bp3/BP3Writer.cpp b/source/adios2/engine/bp3/BP3Writer.cpp
index da25d910e9..8015d4c95d 100644
--- a/source/adios2/engine/bp3/BP3Writer.cpp
+++ b/source/adios2/engine/bp3/BP3Writer.cpp
@@ -330,8 +330,7 @@ void BP3Writer::AggregateWriteData(const bool isFinal, const int transportIndex)
     // async?
     for (int r = 0; r < m_BP3Serializer.m_Aggregator.m_Size; ++r)
     {
-        std::vector<MPI_Request> dataRequests =
-            m_BP3Serializer.m_Aggregator.IExchange(m_BP3Serializer.m_Data, r);
+        m_BP3Serializer.m_Aggregator.IExchange(m_BP3Serializer.m_Data, r);
 
         m_BP3Serializer.m_Aggregator.IExchangeAbsolutePosition(
             m_BP3Serializer.m_Data, r);
@@ -350,7 +349,7 @@ void BP3Writer::AggregateWriteData(const bool isFinal, const int transportIndex)
 
         m_BP3Serializer.m_Aggregator.WaitAbsolutePosition(r);
 
-        m_BP3Serializer.m_Aggregator.Wait(dataRequests, r);
+        m_BP3Serializer.m_Aggregator.Wait(r);
         m_BP3Serializer.m_Aggregator.SwapBuffers(r);
     }
 
diff --git a/source/adios2/engine/bp4/BP4Writer.cpp b/source/adios2/engine/bp4/BP4Writer.cpp
index 3675b177e2..d52e0e6121 100644
--- a/source/adios2/engine/bp4/BP4Writer.cpp
+++ b/source/adios2/engine/bp4/BP4Writer.cpp
@@ -530,8 +530,7 @@ void BP4Writer::AggregateWriteData(const bool isFinal, const int transportIndex)
     // async?
     for (int r = 0; r < m_BP4Serializer.m_Aggregator.m_Size; ++r)
     {
-        std::vector<MPI_Request> dataRequests =
-            m_BP4Serializer.m_Aggregator.IExchange(m_BP4Serializer.m_Data, r);
+        m_BP4Serializer.m_Aggregator.IExchange(m_BP4Serializer.m_Data, r);
 
         m_BP4Serializer.m_Aggregator.IExchangeAbsolutePosition(
             m_BP4Serializer.m_Data, r);
@@ -550,7 +549,7 @@ void BP4Writer::AggregateWriteData(const bool isFinal, const int transportIndex)
 
         m_BP4Serializer.m_Aggregator.WaitAbsolutePosition(r);
 
-        m_BP4Serializer.m_Aggregator.Wait(dataRequests, r);
+        m_BP4Serializer.m_Aggregator.Wait(r);
         m_BP4Serializer.m_Aggregator.SwapBuffers(r);
     }
 
diff --git a/source/adios2/toolkit/aggregator/mpi/MPIAggregator.cpp b/source/adios2/toolkit/aggregator/mpi/MPIAggregator.cpp
index 5dd4febb0c..a379dcf273 100644
--- a/source/adios2/toolkit/aggregator/mpi/MPIAggregator.cpp
+++ b/source/adios2/toolkit/aggregator/mpi/MPIAggregator.cpp
@@ -31,11 +31,8 @@ MPIAggregator::~MPIAggregator()
 
 void MPIAggregator::Init(const size_t subStreams, MPI_Comm parentComm) {}
 
-std::vector<MPI_Request> MPIAggregator::IExchange(BufferSTL & /**bufferSTL*/,
-                                                  const int /** step*/)
+void MPIAggregator::IExchange(BufferSTL & /**bufferSTL*/, const int /** step*/)
 {
-    std::vector<MPI_Request> requests;
-    return requests;
 }
 
 void MPIAggregator::IExchangeAbsolutePosition(BufferSTL &bufferSTL,
@@ -103,10 +100,7 @@ void MPIAggregator::WaitAbsolutePosition(const int step)
     }
 }
 
-void MPIAggregator::Wait(std::vector<MPI_Request> & /**requests*/,
-                         const int /**step*/)
-{
-}
+void MPIAggregator::Wait(const int /**step*/) {}
 
 void MPIAggregator::SwapBuffers(const int step) noexcept {}
 
diff --git a/source/adios2/toolkit/aggregator/mpi/MPIAggregator.h b/source/adios2/toolkit/aggregator/mpi/MPIAggregator.h
index db4ac05f3c..94eed4c935 100644
--- a/source/adios2/toolkit/aggregator/mpi/MPIAggregator.h
+++ b/source/adios2/toolkit/aggregator/mpi/MPIAggregator.h
@@ -62,14 +62,13 @@ class MPIAggregator
 
     virtual void Init(const size_t subStreams, MPI_Comm parentComm);
 
-    virtual std::vector<MPI_Request> IExchange(BufferSTL &bufferSTL,
-                                               const int step);
+    virtual void IExchange(BufferSTL &bufferSTL, const int step);
 
     void IExchangeAbsolutePosition(BufferSTL &bufferSTL, const int step);
 
     void WaitAbsolutePosition(const int step);
 
-    virtual void Wait(std::vector<MPI_Request> &requests, const int step);
+    virtual void Wait(const int step);
 
     virtual void SwapBuffers(const int step) noexcept;
 
diff --git a/source/adios2/toolkit/aggregator/mpi/MPIChain.cpp b/source/adios2/toolkit/aggregator/mpi/MPIChain.cpp
index 2d66790896..965db5db7c 100644
--- a/source/adios2/toolkit/aggregator/mpi/MPIChain.cpp
+++ b/source/adios2/toolkit/aggregator/mpi/MPIChain.cpp
@@ -33,12 +33,11 @@ void MPIChain::Init(const size_t subStreams, MPI_Comm parentComm)
     }
 }
 
-std::vector<MPI_Request> MPIChain::IExchange(BufferSTL &bufferSTL,
-                                             const int step)
+void MPIChain::IExchange(BufferSTL &bufferSTL, const int step)
 {
     if (m_Size == 1)
     {
-        return std::vector<MPI_Request>();
+        return;
     }
 
     BufferSTL &sendBuffer = GetSender(bufferSTL);
@@ -46,20 +45,18 @@ std::vector<MPI_Request> MPIChain::IExchange(BufferSTL &bufferSTL,
     const bool sender = (m_Rank >= 1 && m_Rank <= endRank) ? true : false;
     const bool receiver = (m_Rank < endRank) ? true : false;
 
-    std::vector<MPI_Request> requests(3);
-
     if (sender) // sender
     {
         helper::CheckMPIReturn(MPI_Isend(&sendBuffer.m_Position, 1,
                                          ADIOS2_MPI_SIZE_T, m_Rank - 1, 0,
-                                         m_Comm, &requests[0]),
+                                         m_Comm, &m_DataRequests[0]),
                                ", aggregation Isend size at iteration " +
                                    std::to_string(step) + "\n");
 
         helper::CheckMPIReturn(
             MPI_Isend(sendBuffer.m_Buffer.data(),
                       static_cast<int>(sendBuffer.m_Position), MPI_CHAR,
-                      m_Rank - 1, 1, m_Comm, &requests[1]),
+                      m_Rank - 1, 1, m_Comm, &m_DataRequests[1]),
             ", aggregation Isend data at iteration " + std::to_string(step) +
                 "\n");
     }
@@ -89,15 +86,13 @@ std::vector<MPI_Request> MPIChain::IExchange(BufferSTL &bufferSTL,
         helper::CheckMPIReturn(
             MPI_Irecv(receiveBuffer.m_Buffer.data(),
                       static_cast<int>(receiveBuffer.m_Position), MPI_CHAR,
-                      m_Rank + 1, 1, m_Comm, &requests[2]),
+                      m_Rank + 1, 1, m_Comm, &m_DataRequests[2]),
             ", aggregation Irecv data at iteration " + std::to_string(step) +
                 "\n");
     }
-
-    return requests;
 }
 
-void MPIChain::Wait(std::vector<MPI_Request> &requests, const int step)
+void MPIChain::Wait(const int step)
 {
     if (m_Size == 1)
     {
@@ -112,7 +107,7 @@ void MPIChain::Wait(std::vector<MPI_Request> &requests, const int step)
     if (receiver)
     {
         helper::CheckMPIReturn(
-            MPI_Wait(&requests[2], &status),
+            MPI_Wait(&m_DataRequests[2], &status),
             ", aggregation waiting for receiver data at iteration " +
                 std::to_string(step) + "\n");
     }
@@ -120,12 +115,12 @@ void MPIChain::Wait(std::vector<MPI_Request> &requests, const int step)
     if (sender)
     {
         helper::CheckMPIReturn(
-            MPI_Wait(&requests[0], &status),
+            MPI_Wait(&m_DataRequests[0], &status),
             ", aggregation waiting for sender size at iteration " +
                 std::to_string(step) + "\n");
 
         helper::CheckMPIReturn(
-            MPI_Wait(&requests[1], &status),
+            MPI_Wait(&m_DataRequests[1], &status),
             ", aggregation waiting for sender data at iteration " +
                 std::to_string(step) + "\n");
     }
diff --git a/source/adios2/toolkit/aggregator/mpi/MPIChain.h b/source/adios2/toolkit/aggregator/mpi/MPIChain.h
index 45955e2f96..a688e87390 100644
--- a/source/adios2/toolkit/aggregator/mpi/MPIChain.h
+++ b/source/adios2/toolkit/aggregator/mpi/MPIChain.h
@@ -28,10 +28,9 @@ class MPIChain : public MPIAggregator
 
     void Init(const size_t subStreams, MPI_Comm parentComm) final;
 
-    std::vector<MPI_Request> IExchange(BufferSTL &bufferSTL,
-                                       const int step) final;
+    void IExchange(BufferSTL &bufferSTL, const int step) final;
 
-    void Wait(std::vector<MPI_Request> &request, const int step) final;
+    void Wait(const int step) final;
 
     void SwapBuffers(const int step) noexcept final;
 
@@ -73,6 +72,8 @@ class MPIChain : public MPIAggregator
      */
     void ResizeUpdateBufferSTL(const size_t newSize, BufferSTL &bufferSTL,
                                const std::string hint);
+
+    std::array<MPI_Request, 3> m_DataRequests;
 };
 
 } // end namespace aggregator