--- a/usr/src/uts/common/fs/zfs/zio.c	Fri Jun 27 14:18:08 2008 -0700
+++ b/usr/src/uts/common/fs/zfs/zio.c	Fri Jun 27 17:05:29 2008 -0700
@@ -1834,8 +1834,12 @@
 		return (B_FALSE);
 	if (zio->io_delegate_list != NULL)
 		return (B_FALSE);
-	if (vd && vd != vd->vdev_top)
-		return (B_FALSE);
+	if (vd != NULL) {
+		if (vd != vd->vdev_top)
+			return (B_FALSE);
+		if (vd->vdev_is_failing)
+			return (B_FALSE);
+	}
 	if (zio->io_flags & ZIO_FLAG_DONT_RETRY)
 		return (B_FALSE);
 	if (zio->io_retries > 0)