3606 zpool status -x shouldn't warn about old on-disk format

Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Richard Elling <richard.elling@dey-sys.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Dan McDonald <danmcd@nexenta.com>

usr/src/cmd/zpool/zpool_main.c

@@ -3923,7 +3923,10 @@ status_callback(zpool_handle_t *zhp, void *data)
 	 * If we were given 'zpool status -x', only report those pools with
 	 * problems.
 	 */
-	if (reason == ZPOOL_STATUS_OK && cbp->cb_explain) {
+	if (cbp->cb_explain &&
+	    (reason == ZPOOL_STATUS_OK ||
+	    reason == ZPOOL_STATUS_VERSION_OLDER ||
+	    reason == ZPOOL_STATUS_FEAT_DISABLED)) {
 		if (!cbp->cb_allpools) {
 			(void) printf(gettext("pool '%s' is healthy\n"),
 			    zpool_get_name(zhp));

usr/src/man/man1m/zpool.1m

@@ -1685,7 +1685,8 @@ can change.
 .ad
 .RS 6n
 Only display status for pools that are exhibiting errors or are otherwise
-unavailable.
+unavailable. Warnings about pools not using the latest on-disk format will
+not be included.
 .RE
 
 .sp