1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright 2010 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 /*
27 * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
28 */
29
30 #include <sys/zfs_context.h>
31 #include <sys/spa.h>
32 #include <sys/vdev_impl.h>
33 #include <sys/zio.h>
34 #include <sys/fs/zfs.h>
35
36 /*
37 * Virtual device vector for mirroring.
38 */
39
40 typedef struct mirror_child {
41 vdev_t *mc_vd;
42 uint64_t mc_offset;
43 int mc_error;
44 int mc_load;
45 uint8_t mc_tried;
46 uint8_t mc_skipped;
47 uint8_t mc_speculative;
48 } mirror_child_t;
49
50 typedef struct mirror_map {
51 int *mm_preferred;
52 int mm_preferred_cnt;
53 int mm_children;
54 boolean_t mm_replacing;
55 boolean_t mm_root;
56 mirror_child_t mm_child[];
57 } mirror_map_t;
58
59 static int vdev_mirror_shift = 21;
60
61 #ifdef __FreeBSD__
62 #ifdef _KERNEL
63 SYSCTL_DECL(_vfs_zfs_vdev);
64 static SYSCTL_NODE(_vfs_zfs_vdev, OID_AUTO, mirror, CTLFLAG_RD, 0,
65 "ZFS VDEV Mirror");
66 #endif
67 #endif
68
69 /*
70 * The load configuration settings below are tuned by default for
71 * the case where all devices are of the same rotational type.
72 *
73 * If there is a mixture of rotating and non-rotating media, setting
74 * non_rotating_seek_inc to 0 may well provide better results as it
75 * will direct more reads to the non-rotating vdevs which are more
76 * likely to have a higher performance.
77 */
78
79 /* Rotating media load calculation configuration. */
80 static int rotating_inc = 0;
81 #ifdef _KERNEL
82 SYSCTL_INT(_vfs_zfs_vdev_mirror, OID_AUTO, rotating_inc, CTLFLAG_RWTUN,
83 &rotating_inc, 0, "Rotating media load increment for non-seeking I/O's");
84 #endif
85
86 static int rotating_seek_inc = 5;
87 #ifdef _KERNEL
88 SYSCTL_INT(_vfs_zfs_vdev_mirror, OID_AUTO, rotating_seek_inc, CTLFLAG_RWTUN,
89 &rotating_seek_inc, 0, "Rotating media load increment for seeking I/O's");
90 #endif
91
92 static int rotating_seek_offset = 1 * 1024 * 1024;
93 #ifdef _KERNEL
94 SYSCTL_INT(_vfs_zfs_vdev_mirror, OID_AUTO, rotating_seek_offset, CTLFLAG_RWTUN,
95 &rotating_seek_offset, 0, "Offset in bytes from the last I/O which "
96 "triggers a reduced rotating media seek increment");
97 #endif
98
99 /* Non-rotating media load calculation configuration. */
100 static int non_rotating_inc = 0;
101 #ifdef _KERNEL
102 SYSCTL_INT(_vfs_zfs_vdev_mirror, OID_AUTO, non_rotating_inc, CTLFLAG_RWTUN,
103 &non_rotating_inc, 0,
104 "Non-rotating media load increment for non-seeking I/O's");
105 #endif
106
107 static int non_rotating_seek_inc = 1;
108 #ifdef _KERNEL
109 SYSCTL_INT(_vfs_zfs_vdev_mirror, OID_AUTO, non_rotating_seek_inc, CTLFLAG_RWTUN,
110 &non_rotating_seek_inc, 0,
111 "Non-rotating media load increment for seeking I/O's");
112 #endif
113
114
115 static inline size_t
vdev_mirror_map_size(int children)116 vdev_mirror_map_size(int children)
117 {
118 return (offsetof(mirror_map_t, mm_child[children]) +
119 sizeof(int) * children);
120 }
121
122 static inline mirror_map_t *
vdev_mirror_map_alloc(int children,boolean_t replacing,boolean_t root)123 vdev_mirror_map_alloc(int children, boolean_t replacing, boolean_t root)
124 {
125 mirror_map_t *mm;
126
127 mm = kmem_zalloc(vdev_mirror_map_size(children), KM_SLEEP);
128 mm->mm_children = children;
129 mm->mm_replacing = replacing;
130 mm->mm_root = root;
131 mm->mm_preferred = (int *)((uintptr_t)mm +
132 offsetof(mirror_map_t, mm_child[children]));
133
134 return mm;
135 }
136
137 static void
vdev_mirror_map_free(zio_t * zio)138 vdev_mirror_map_free(zio_t *zio)
139 {
140 mirror_map_t *mm = zio->io_vsd;
141
142 kmem_free(mm, vdev_mirror_map_size(mm->mm_children));
143 }
144
145 static const zio_vsd_ops_t vdev_mirror_vsd_ops = {
146 vdev_mirror_map_free,
147 zio_vsd_default_cksum_report
148 };
149
150 static int
vdev_mirror_load(mirror_map_t * mm,vdev_t * vd,uint64_t zio_offset)151 vdev_mirror_load(mirror_map_t *mm, vdev_t *vd, uint64_t zio_offset)
152 {
153 uint64_t lastoffset;
154 int load;
155
156 /* All DVAs have equal weight at the root. */
157 if (mm->mm_root)
158 return (INT_MAX);
159
160 /*
161 * We don't return INT_MAX if the device is resilvering i.e.
162 * vdev_resilver_txg != 0 as when tested performance was slightly
163 * worse overall when resilvering with compared to without.
164 */
165
166 /* Standard load based on pending queue length. */
167 load = vdev_queue_length(vd);
168 lastoffset = vdev_queue_lastoffset(vd);
169
170 if (vd->vdev_rotation_rate == VDEV_RATE_NON_ROTATING) {
171 /* Non-rotating media. */
172 if (lastoffset == zio_offset)
173 return (load + non_rotating_inc);
174
175 /*
176 * Apply a seek penalty even for non-rotating devices as
177 * sequential I/O'a can be aggregated into fewer operations
178 * on the device, thus avoiding unnecessary per-command
179 * overhead and boosting performance.
180 */
181 return (load + non_rotating_seek_inc);
182 }
183
184 /* Rotating media I/O's which directly follow the last I/O. */
185 if (lastoffset == zio_offset)
186 return (load + rotating_inc);
187
188 /*
189 * Apply half the seek increment to I/O's within seek offset
190 * of the last I/O queued to this vdev as they should incure less
191 * of a seek increment.
192 */
193 if (ABS(lastoffset - zio_offset) < rotating_seek_offset)
194 return (load + (rotating_seek_inc / 2));
195
196 /* Apply the full seek increment to all other I/O's. */
197 return (load + rotating_seek_inc);
198 }
199
200
201 static mirror_map_t *
vdev_mirror_map_init(zio_t * zio)202 vdev_mirror_map_init(zio_t *zio)
203 {
204 mirror_map_t *mm = NULL;
205 mirror_child_t *mc;
206 vdev_t *vd = zio->io_vd;
207 int c;
208
209 if (vd == NULL) {
210 dva_t *dva = zio->io_bp->blk_dva;
211 spa_t *spa = zio->io_spa;
212
213 mm = vdev_mirror_map_alloc(BP_GET_NDVAS(zio->io_bp), B_FALSE,
214 B_TRUE);
215 for (c = 0; c < mm->mm_children; c++) {
216 mc = &mm->mm_child[c];
217 mc->mc_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[c]));
218 mc->mc_offset = DVA_GET_OFFSET(&dva[c]);
219 }
220 } else {
221 mm = vdev_mirror_map_alloc(vd->vdev_children,
222 (vd->vdev_ops == &vdev_replacing_ops ||
223 vd->vdev_ops == &vdev_spare_ops), B_FALSE);
224 for (c = 0; c < mm->mm_children; c++) {
225 mc = &mm->mm_child[c];
226 mc->mc_vd = vd->vdev_child[c];
227 mc->mc_offset = zio->io_offset;
228 }
229 }
230
231 zio->io_vsd = mm;
232 zio->io_vsd_ops = &vdev_mirror_vsd_ops;
233 return (mm);
234 }
235
236 static int
vdev_mirror_open(vdev_t * vd,uint64_t * asize,uint64_t * max_asize,uint64_t * logical_ashift,uint64_t * physical_ashift)237 vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
238 uint64_t *logical_ashift, uint64_t *physical_ashift)
239 {
240 int numerrors = 0;
241 int lasterror = 0;
242
243 if (vd->vdev_children == 0) {
244 vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
245 return (SET_ERROR(EINVAL));
246 }
247
248 vdev_open_children(vd);
249
250 for (int c = 0; c < vd->vdev_children; c++) {
251 vdev_t *cvd = vd->vdev_child[c];
252
253 if (cvd->vdev_open_error) {
254 lasterror = cvd->vdev_open_error;
255 numerrors++;
256 continue;
257 }
258
259 *asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1;
260 *max_asize = MIN(*max_asize - 1, cvd->vdev_max_asize - 1) + 1;
261 *logical_ashift = MAX(*logical_ashift, cvd->vdev_ashift);
262 *physical_ashift = MAX(*physical_ashift,
263 cvd->vdev_physical_ashift);
264 }
265
266 if (numerrors == vd->vdev_children) {
267 vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
268 return (lasterror);
269 }
270
271 return (0);
272 }
273
274 static void
vdev_mirror_close(vdev_t * vd)275 vdev_mirror_close(vdev_t *vd)
276 {
277 for (int c = 0; c < vd->vdev_children; c++)
278 vdev_close(vd->vdev_child[c]);
279 }
280
281 static void
vdev_mirror_child_done(zio_t * zio)282 vdev_mirror_child_done(zio_t *zio)
283 {
284 mirror_child_t *mc = zio->io_private;
285
286 mc->mc_error = zio->io_error;
287 mc->mc_tried = 1;
288 mc->mc_skipped = 0;
289 }
290
291 static void
vdev_mirror_scrub_done(zio_t * zio)292 vdev_mirror_scrub_done(zio_t *zio)
293 {
294 mirror_child_t *mc = zio->io_private;
295
296 if (zio->io_error == 0) {
297 zio_t *pio;
298 zio_link_t *zl = NULL;
299
300 mutex_enter(&zio->io_lock);
301 while ((pio = zio_walk_parents(zio, &zl)) != NULL) {
302 mutex_enter(&pio->io_lock);
303 ASSERT3U(zio->io_size, >=, pio->io_size);
304 bcopy(zio->io_data, pio->io_data, pio->io_size);
305 mutex_exit(&pio->io_lock);
306 }
307 mutex_exit(&zio->io_lock);
308 }
309
310 zio_buf_free(zio->io_data, zio->io_size);
311
312 mc->mc_error = zio->io_error;
313 mc->mc_tried = 1;
314 mc->mc_skipped = 0;
315 }
316
317 /*
318 * Check the other, lower-index DVAs to see if they're on the same
319 * vdev as the child we picked. If they are, use them since they
320 * are likely to have been allocated from the primary metaslab in
321 * use at the time, and hence are more likely to have locality with
322 * single-copy data.
323 */
324 static int
vdev_mirror_dva_select(zio_t * zio,int p)325 vdev_mirror_dva_select(zio_t *zio, int p)
326 {
327 dva_t *dva = zio->io_bp->blk_dva;
328 mirror_map_t *mm = zio->io_vsd;
329 int preferred;
330 int c;
331
332 preferred = mm->mm_preferred[p];
333 for (p-- ; p >= 0; p--) {
334 c = mm->mm_preferred[p];
335 if (DVA_GET_VDEV(&dva[c]) == DVA_GET_VDEV(&dva[preferred]))
336 preferred = c;
337 }
338 return (preferred);
339 }
340
341 static int
vdev_mirror_preferred_child_randomize(zio_t * zio)342 vdev_mirror_preferred_child_randomize(zio_t *zio)
343 {
344 mirror_map_t *mm = zio->io_vsd;
345 int p;
346
347 if (mm->mm_root) {
348 p = spa_get_random(mm->mm_preferred_cnt);
349 return (vdev_mirror_dva_select(zio, p));
350 }
351
352 /*
353 * To ensure we don't always favour the first matching vdev,
354 * which could lead to wear leveling issues on SSD's, we
355 * use the I/O offset as a pseudo random seed into the vdevs
356 * which have the lowest load.
357 */
358 p = (zio->io_offset >> vdev_mirror_shift) % mm->mm_preferred_cnt;
359 return (mm->mm_preferred[p]);
360 }
361
362 /*
363 * Try to find a vdev whose DTL doesn't contain the block we want to read
364 * prefering vdevs based on determined load.
365 *
366 * If we can't, try the read on any vdev we haven't already tried.
367 */
368 static int
vdev_mirror_child_select(zio_t * zio)369 vdev_mirror_child_select(zio_t *zio)
370 {
371 mirror_map_t *mm = zio->io_vsd;
372 uint64_t txg = zio->io_txg;
373 int c, lowest_load;
374
375 ASSERT(zio->io_bp == NULL || BP_PHYSICAL_BIRTH(zio->io_bp) == txg);
376
377 lowest_load = INT_MAX;
378 mm->mm_preferred_cnt = 0;
379 for (c = 0; c < mm->mm_children; c++) {
380 mirror_child_t *mc;
381
382 mc = &mm->mm_child[c];
383 if (mc->mc_tried || mc->mc_skipped)
384 continue;
385
386 if (!vdev_readable(mc->mc_vd)) {
387 mc->mc_error = SET_ERROR(ENXIO);
388 mc->mc_tried = 1; /* don't even try */
389 mc->mc_skipped = 1;
390 continue;
391 }
392
393 if (vdev_dtl_contains(mc->mc_vd, DTL_MISSING, txg, 1)) {
394 mc->mc_error = SET_ERROR(ESTALE);
395 mc->mc_skipped = 1;
396 mc->mc_speculative = 1;
397 continue;
398 }
399
400 mc->mc_load = vdev_mirror_load(mm, mc->mc_vd, mc->mc_offset);
401 if (mc->mc_load > lowest_load)
402 continue;
403
404 if (mc->mc_load < lowest_load) {
405 lowest_load = mc->mc_load;
406 mm->mm_preferred_cnt = 0;
407 }
408 mm->mm_preferred[mm->mm_preferred_cnt] = c;
409 mm->mm_preferred_cnt++;
410 }
411
412 if (mm->mm_preferred_cnt == 1) {
413 vdev_queue_register_lastoffset(
414 mm->mm_child[mm->mm_preferred[0]].mc_vd, zio);
415 return (mm->mm_preferred[0]);
416 }
417
418 if (mm->mm_preferred_cnt > 1) {
419 int c = vdev_mirror_preferred_child_randomize(zio);
420
421 vdev_queue_register_lastoffset(mm->mm_child[c].mc_vd, zio);
422 return (c);
423 }
424
425 /*
426 * Every device is either missing or has this txg in its DTL.
427 * Look for any child we haven't already tried before giving up.
428 */
429 for (c = 0; c < mm->mm_children; c++) {
430 if (!mm->mm_child[c].mc_tried) {
431 vdev_queue_register_lastoffset(mm->mm_child[c].mc_vd,
432 zio);
433 return (c);
434 }
435 }
436
437 /*
438 * Every child failed. There's no place left to look.
439 */
440 return (-1);
441 }
442
443 static void
vdev_mirror_io_start(zio_t * zio)444 vdev_mirror_io_start(zio_t *zio)
445 {
446 mirror_map_t *mm;
447 mirror_child_t *mc;
448 int c, children;
449
450 mm = vdev_mirror_map_init(zio);
451
452 if (zio->io_type == ZIO_TYPE_READ) {
453 if ((zio->io_flags & ZIO_FLAG_SCRUB) && !mm->mm_replacing &&
454 mm->mm_children > 1) {
455 /*
456 * For scrubbing reads we need to allocate a read
457 * buffer for each child and issue reads to all
458 * children. If any child succeeds, it will copy its
459 * data into zio->io_data in vdev_mirror_scrub_done.
460 */
461 for (c = 0; c < mm->mm_children; c++) {
462 mc = &mm->mm_child[c];
463 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
464 mc->mc_vd, mc->mc_offset,
465 zio_buf_alloc(zio->io_size), zio->io_size,
466 zio->io_type, zio->io_priority, 0,
467 vdev_mirror_scrub_done, mc));
468 }
469 zio_execute(zio);
470 return;
471 }
472 /*
473 * For normal reads just pick one child.
474 */
475 c = vdev_mirror_child_select(zio);
476 children = (c >= 0);
477 } else {
478 ASSERT(zio->io_type == ZIO_TYPE_WRITE ||
479 zio->io_type == ZIO_TYPE_FREE);
480
481 /*
482 * Writes and frees go to all children.
483 */
484 c = 0;
485 children = mm->mm_children;
486 }
487
488 while (children--) {
489 mc = &mm->mm_child[c];
490 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
491 mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
492 zio->io_type, zio->io_priority, 0,
493 vdev_mirror_child_done, mc));
494 c++;
495 }
496
497 zio_execute(zio);
498 }
499
500 static int
vdev_mirror_worst_error(mirror_map_t * mm)501 vdev_mirror_worst_error(mirror_map_t *mm)
502 {
503 int error[2] = { 0, 0 };
504
505 for (int c = 0; c < mm->mm_children; c++) {
506 mirror_child_t *mc = &mm->mm_child[c];
507 int s = mc->mc_speculative;
508 error[s] = zio_worst_error(error[s], mc->mc_error);
509 }
510
511 return (error[0] ? error[0] : error[1]);
512 }
513
514 static void
vdev_mirror_io_done(zio_t * zio)515 vdev_mirror_io_done(zio_t *zio)
516 {
517 mirror_map_t *mm = zio->io_vsd;
518 mirror_child_t *mc;
519 int c;
520 int good_copies = 0;
521 int unexpected_errors = 0;
522
523 for (c = 0; c < mm->mm_children; c++) {
524 mc = &mm->mm_child[c];
525
526 if (mc->mc_error) {
527 if (!mc->mc_skipped)
528 unexpected_errors++;
529 } else if (mc->mc_tried) {
530 good_copies++;
531 }
532 }
533
534 if (zio->io_type == ZIO_TYPE_WRITE) {
535 /*
536 * XXX -- for now, treat partial writes as success.
537 *
538 * Now that we support write reallocation, it would be better
539 * to treat partial failure as real failure unless there are
540 * no non-degraded top-level vdevs left, and not update DTLs
541 * if we intend to reallocate.
542 */
543 /* XXPOLICY */
544 if (good_copies != mm->mm_children) {
545 /*
546 * Always require at least one good copy.
547 *
548 * For ditto blocks (io_vd == NULL), require
549 * all copies to be good.
550 *
551 * XXX -- for replacing vdevs, there's no great answer.
552 * If the old device is really dead, we may not even
553 * be able to access it -- so we only want to
554 * require good writes to the new device. But if
555 * the new device turns out to be flaky, we want
556 * to be able to detach it -- which requires all
557 * writes to the old device to have succeeded.
558 */
559 if (good_copies == 0 || zio->io_vd == NULL)
560 zio->io_error = vdev_mirror_worst_error(mm);
561 }
562 return;
563 } else if (zio->io_type == ZIO_TYPE_FREE) {
564 return;
565 }
566
567 ASSERT(zio->io_type == ZIO_TYPE_READ);
568
569 /*
570 * If we don't have a good copy yet, keep trying other children.
571 */
572 /* XXPOLICY */
573 if (good_copies == 0 && (c = vdev_mirror_child_select(zio)) != -1) {
574 ASSERT(c >= 0 && c < mm->mm_children);
575 mc = &mm->mm_child[c];
576 zio_vdev_io_redone(zio);
577 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
578 mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
579 ZIO_TYPE_READ, zio->io_priority, 0,
580 vdev_mirror_child_done, mc));
581 return;
582 }
583
584 /* XXPOLICY */
585 if (good_copies == 0) {
586 zio->io_error = vdev_mirror_worst_error(mm);
587 ASSERT(zio->io_error != 0);
588 }
589
590 if (good_copies && spa_writeable(zio->io_spa) &&
591 (unexpected_errors ||
592 (zio->io_flags & ZIO_FLAG_RESILVER) ||
593 ((zio->io_flags & ZIO_FLAG_SCRUB) && mm->mm_replacing))) {
594 /*
595 * Use the good data we have in hand to repair damaged children.
596 */
597 for (c = 0; c < mm->mm_children; c++) {
598 /*
599 * Don't rewrite known good children.
600 * Not only is it unnecessary, it could
601 * actually be harmful: if the system lost
602 * power while rewriting the only good copy,
603 * there would be no good copies left!
604 */
605 mc = &mm->mm_child[c];
606
607 if (mc->mc_error == 0) {
608 if (mc->mc_tried)
609 continue;
610 if (!(zio->io_flags & ZIO_FLAG_SCRUB) &&
611 !vdev_dtl_contains(mc->mc_vd, DTL_PARTIAL,
612 zio->io_txg, 1))
613 continue;
614 mc->mc_error = SET_ERROR(ESTALE);
615 }
616
617 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
618 mc->mc_vd, mc->mc_offset,
619 zio->io_data, zio->io_size,
620 ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE,
621 ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
622 ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
623 }
624 }
625 }
626
627 static void
vdev_mirror_state_change(vdev_t * vd,int faulted,int degraded)628 vdev_mirror_state_change(vdev_t *vd, int faulted, int degraded)
629 {
630 if (faulted == vd->vdev_children)
631 vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
632 VDEV_AUX_NO_REPLICAS);
633 else if (degraded + faulted != 0)
634 vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
635 else
636 vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
637 }
638
639 vdev_ops_t vdev_mirror_ops = {
640 vdev_mirror_open,
641 vdev_mirror_close,
642 vdev_default_asize,
643 vdev_mirror_io_start,
644 vdev_mirror_io_done,
645 vdev_mirror_state_change,
646 NULL,
647 NULL,
648 VDEV_TYPE_MIRROR, /* name of this vdev type */
649 B_FALSE /* not a leaf vdev */
650 };
651
652 vdev_ops_t vdev_replacing_ops = {
653 vdev_mirror_open,
654 vdev_mirror_close,
655 vdev_default_asize,
656 vdev_mirror_io_start,
657 vdev_mirror_io_done,
658 vdev_mirror_state_change,
659 NULL,
660 NULL,
661 VDEV_TYPE_REPLACING, /* name of this vdev type */
662 B_FALSE /* not a leaf vdev */
663 };
664
665 vdev_ops_t vdev_spare_ops = {
666 vdev_mirror_open,
667 vdev_mirror_close,
668 vdev_default_asize,
669 vdev_mirror_io_start,
670 vdev_mirror_io_done,
671 vdev_mirror_state_change,
672 NULL,
673 NULL,
674 VDEV_TYPE_SPARE, /* name of this vdev type */
675 B_FALSE /* not a leaf vdev */
676 };
677