diff --git a/lib/libdevstat/devstat.h b/lib/libdevstat/devstat.h
index 9c6a9511a14c..d688eb787262 100644
--- a/lib/libdevstat/devstat.h
+++ b/lib/libdevstat/devstat.h
@@ -43,7 +43,7 @@
  * backwards-compatible API changes, so application writers have a way to 
  * determine when a particular feature is available.
  */
-#define	DEVSTAT_USER_API_VER	4
+#define	DEVSTAT_USER_API_VER	5
 
 #define DEVSTAT_ERRBUF_SIZE  2048 /* size of the devstat library error string */
 
@@ -61,12 +61,10 @@ typedef enum {
 	DSM_TOTAL_BYTES,
 	DSM_TOTAL_BYTES_READ,
 	DSM_TOTAL_BYTES_WRITE,
-	DSM_TOTAL_BYTES_FREE,
 	DSM_TOTAL_TRANSFERS,
 	DSM_TOTAL_TRANSFERS_OTHER,
 	DSM_TOTAL_TRANSFERS_READ,
 	DSM_TOTAL_TRANSFERS_WRITE,
-	DSM_TOTAL_TRANSFERS_FREE,
 	DSM_TOTAL_BLOCKS,
 	DSM_TOTAL_BLOCKS_READ,
 	DSM_TOTAL_BLOCKS_WRITE,
@@ -74,28 +72,30 @@ typedef enum {
 	DSM_KB_PER_TRANSFER,
 	DSM_KB_PER_TRANSFER_READ,
 	DSM_KB_PER_TRANSFER_WRITE,
-	DSM_KB_PER_TRANSFER_FREE,
 	DSM_TRANSFERS_PER_SECOND,
 	DSM_TRANSFERS_PER_SECOND_OTHER,
 	DSM_TRANSFERS_PER_SECOND_READ,
 	DSM_TRANSFERS_PER_SECOND_WRITE,
-	DSM_TRANSFERS_PER_SECOND_FREE,
 	DSM_MB_PER_SECOND,
 	DSM_MB_PER_SECOND_READ,
 	DSM_MB_PER_SECOND_WRITE,
-	DSM_MB_PER_SECOND_FREE,
 	DSM_BLOCKS_PER_SECOND,
 	DSM_BLOCKS_PER_SECOND_READ,
 	DSM_BLOCKS_PER_SECOND_WRITE,
-	DSM_BLOCKS_PER_SECOND_FREE,
 	DSM_MS_PER_TRANSACTION,
-	DSM_MS_PER_TRANSACTION_OTHER,
 	DSM_MS_PER_TRANSACTION_READ,
 	DSM_MS_PER_TRANSACTION_WRITE,
+	DSM_SKIP,
+	DSM_TOTAL_BYTES_FREE,
+	DSM_TOTAL_TRANSFERS_FREE,
+	DSM_KB_PER_TRANSFER_FREE,
+	DSM_MB_PER_SECOND_FREE,
+	DSM_TRANSFERS_PER_SECOND_FREE,
+	DSM_BLOCKS_PER_SECOND_FREE,
+	DSM_MS_PER_TRANSACTION_OTHER,
 	DSM_MS_PER_TRANSACTION_FREE,
 	DSM_BUSY_PCT,
 	DSM_QUEUE_LENGTH,
-	DSM_SKIP,
 	DSM_MAX
 } devstat_metric;