3507 Tunable to allow block allocation even on degraded vdevs

Reviewed by: George Wilson <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Approved by: Christopher Siden <[email protected]>
illumos · Feb 5, 2013 · 9dc3941 · 9dc3941
1 parent e98f46c
commit 9dc3941
Showing 1 changed file with 10 additions and 1 deletion.
diff --git a/usr/src/uts/common/fs/zfs/metaslab.c b/usr/src/uts/common/fs/zfs/metaslab.c
@@ -21,6 +21,7 @@
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012 by Delphix. All rights reserved.
+ * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -90,6 +91,11 @@ int metaslab_prefetch_limit = SPA_DVAS_PER_BP;
  */
 int metaslab_smo_bonus_pct = 150;
 
+/*
+ * Should we be willing to write data to degraded vdevs?
+ */
+boolean_t zfs_write_to_degraded = B_FALSE;
+
 /*
  * ==========================================================================
  * Metaslab classes
@@ -1377,10 +1383,13 @@ metaslab_alloc_dva(spa_t *spa, metaslab_class_t *mc, uint64_t psize,
 
 		/*
 		 * Avoid writing single-copy data to a failing vdev
+		 * unless the user instructs us that it is okay.
 		 */
 		if ((vd->vdev_stat.vs_write_errors > 0 ||
 		    vd->vdev_state < VDEV_STATE_HEALTHY) &&
-		    d == 0 && dshift == 3) {
+		    d == 0 && dshift == 3 &&
+		    !(zfs_write_to_degraded && vd->vdev_state ==
+		    VDEV_STATE_DEGRADED)) {
 			all_zero = B_FALSE;
 			goto next;
 		}