HDDS-1500. Allocate block failures in client should print exception trace. Contributed by Aravindan Vijayan (#801).

hadoop-ozone/client/src/main/java/org/apache/hadoop/ozone/client/io/BlockOutputStreamEntryPool.java

@@ -297,7 +297,7 @@ BlockOutputStreamEntry allocateBlockIfNeeded() throws IOException {
         succeededAllocates += 1;
       } catch (IOException ioe) {
         LOG.error("Try to allocate more blocks for write failed, already "
-            + "allocated " + succeededAllocates + " blocks for this write.");
+            + "allocated {} blocks for this write.", succeededAllocates, ioe);
         throw ioe;
       }
     }
@@ -341,4 +341,4 @@ public long getStreamBufferMaxSize() {
   boolean isEmpty() {
     return streamEntries.isEmpty();
   }
-}
+}