Distributed Spare (dRAID) Feature

This patch adds a new top-level vdev type called dRAID, which stands
for Distributed parity RAID.  This pool configuration allows all dRAID
vdevs to participate when rebuilding to a distributed hot spare device.
This can substantially reduce the total time required to restore full
parity to pool with a failed device.

A dRAID pool can be created using the new top-level `draid` type.
Like `raidz`, the desired redundancy is specified after the type:
`draid[1,2,3]`.  No additional information is required to create the
pool and reasonable default values will be chosen based on the number
of child vdevs in the dRAID vdev.

    zpool create <pool> draid[1,2,3] <vdevs...>

Unlike raidz, additional optional dRAID configuration values can be
provided as part of the draid type as colon separated values. This
allows administrators to fully specify a layout for either performance
or capacity reasons.  The supported options include:

    zpool create <pool> \
        draid[<parity>][:<data>d][:<children>c][:<spares>s] \
        <vdevs...>

    - draid[parity]       - Parity level (default 1)
    - draid[:<data>d]     - Data devices per group (default 8)
    - draid[:<children>c] - Expected number of child vdevs
    - draid[:<spares>s]   - Distributed hot spares (default 0)

Abbreviated example `zpool status` output for a 68 disk dRAID pool
with two distributed spares using special allocation classes.

```
  pool: tank
 state: ONLINE
config:

    NAME                  STATE     READ WRITE CKSUM
    slag7                 ONLINE       0     0     0
      draid2:8d:68c:2s-0  ONLINE       0     0     0
        L0                ONLINE       0     0     0
        L1                ONLINE       0     0     0
        ...
        U25               ONLINE       0     0     0
        U26               ONLINE       0     0     0
        spare-53          ONLINE       0     0     0
          U27             ONLINE       0     0     0
          draid2-0-0      ONLINE       0     0     0
        U28               ONLINE       0     0     0
        U29               ONLINE       0     0     0
        ...
        U42               ONLINE       0     0     0
        U43               ONLINE       0     0     0
    special
      mirror-1            ONLINE       0     0     0
        L5                ONLINE       0     0     0
        U5                ONLINE       0     0     0
      mirror-2            ONLINE       0     0     0
        L6                ONLINE       0     0     0
        U6                ONLINE       0     0     0
    spares
      draid2-0-0          INUSE     currently in use
      draid2-0-1          AVAIL
```

When adding test coverage for the new dRAID vdev type the following
options were added to the ztest command.  These options are leverages
by zloop.sh to test a wide range of dRAID configurations.

    -K draid|raidz|random - kind of RAID to test
    -D <value>            - dRAID data drives per group
    -S <value>            - dRAID distributed hot spares
    -R <value>            - RAID parity (raidz or dRAID)

The zpool_create, zpool_import, redundancy, replacement and fault
test groups have all been updated provide test coverage for the
dRAID feature.

Co-authored-by: Isaac Huang <he.huang@intel.com>
Co-authored-by: Mark Maybee <mmaybee@cray.com>
Co-authored-by: Don Brady <don.brady@delphix.com>
Co-authored-by: Matthew Ahrens <mahrens@delphix.com>
Co-authored-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Mark Maybee <mmaybee@cray.com>
Reviewed-by: Matt Ahrens <matt@delphix.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #10102
This commit is contained in:
Brian Behlendorf
2020-11-13 13:51:51 -08:00
committed by GitHub
parent a724db0374
commit b2255edcc0
153 changed files with 10203 additions and 1882 deletions
+3 -2
View File
@@ -2294,7 +2294,7 @@ print_status_config(zpool_handle_t *zhp, status_cbdata_t *cb, const char *name,
}
}
/* Display vdev initialization and trim status for leaves */
/* Display vdev initialization and trim status for leaves. */
if (children == 0) {
print_status_initialize(vs, cb->cb_print_vdev_init);
print_status_trim(vs, cb->cb_print_vdev_trim);
@@ -9849,7 +9849,8 @@ vdev_any_spare_replacing(nvlist_t *nv)
(void) nvlist_lookup_string(nv, ZPOOL_CONFIG_TYPE, &vdev_type);
if (strcmp(vdev_type, VDEV_TYPE_REPLACING) == 0 ||
strcmp(vdev_type, VDEV_TYPE_SPARE) == 0) {
strcmp(vdev_type, VDEV_TYPE_SPARE) == 0 ||
strcmp(vdev_type, VDEV_TYPE_DRAID_SPARE) == 0) {
return (B_TRUE);
}
+345 -56
View File
@@ -86,9 +86,6 @@
boolean_t error_seen;
boolean_t is_force;
/*PRINTFLIKE1*/
void
vdev_error(const char *fmt, ...)
@@ -222,6 +219,9 @@ is_spare(nvlist_t *config, const char *path)
uint_t i, nspares;
boolean_t inuse;
if (zpool_is_draid_spare(path))
return (B_TRUE);
if ((fd = open(path, O_RDONLY|O_DIRECT)) < 0)
return (B_FALSE);
@@ -267,9 +267,10 @@ is_spare(nvlist_t *config, const char *path)
* /dev/xxx Complete disk path
* /xxx Full path to file
* xxx Shorthand for <zfs_vdev_paths>/xxx
* draid* Virtual dRAID spare
*/
static nvlist_t *
make_leaf_vdev(nvlist_t *props, const char *arg, uint64_t is_log)
make_leaf_vdev(nvlist_t *props, const char *arg, boolean_t is_primary)
{
char path[MAXPATHLEN];
struct stat64 statbuf;
@@ -309,6 +310,17 @@ make_leaf_vdev(nvlist_t *props, const char *arg, uint64_t is_log)
/* After whole disk check restore original passed path */
strlcpy(path, arg, sizeof (path));
} else if (zpool_is_draid_spare(arg)) {
if (!is_primary) {
(void) fprintf(stderr,
gettext("cannot open '%s': dRAID spares can only "
"be used to replace primary vdevs\n"), arg);
return (NULL);
}
wholedisk = B_TRUE;
strlcpy(path, arg, sizeof (path));
type = VDEV_TYPE_DRAID_SPARE;
} else {
err = is_shorthand_path(arg, path, sizeof (path),
&statbuf, &wholedisk);
@@ -337,17 +349,19 @@ make_leaf_vdev(nvlist_t *props, const char *arg, uint64_t is_log)
}
}
/*
* Determine whether this is a device or a file.
*/
if (wholedisk || S_ISBLK(statbuf.st_mode)) {
type = VDEV_TYPE_DISK;
} else if (S_ISREG(statbuf.st_mode)) {
type = VDEV_TYPE_FILE;
} else {
(void) fprintf(stderr, gettext("cannot use '%s': must be a "
"block device or regular file\n"), path);
return (NULL);
if (type == NULL) {
/*
* Determine whether this is a device or a file.
*/
if (wholedisk || S_ISBLK(statbuf.st_mode)) {
type = VDEV_TYPE_DISK;
} else if (S_ISREG(statbuf.st_mode)) {
type = VDEV_TYPE_FILE;
} else {
fprintf(stderr, gettext("cannot use '%s': must "
"be a block device or regular file\n"), path);
return (NULL);
}
}
/*
@@ -358,10 +372,7 @@ make_leaf_vdev(nvlist_t *props, const char *arg, uint64_t is_log)
verify(nvlist_alloc(&vdev, NV_UNIQUE_NAME, 0) == 0);
verify(nvlist_add_string(vdev, ZPOOL_CONFIG_PATH, path) == 0);
verify(nvlist_add_string(vdev, ZPOOL_CONFIG_TYPE, type) == 0);
verify(nvlist_add_uint64(vdev, ZPOOL_CONFIG_IS_LOG, is_log) == 0);
if (is_log)
verify(nvlist_add_string(vdev, ZPOOL_CONFIG_ALLOCATION_BIAS,
VDEV_ALLOC_BIAS_LOG) == 0);
if (strcmp(type, VDEV_TYPE_DISK) == 0)
verify(nvlist_add_uint64(vdev, ZPOOL_CONFIG_WHOLE_DISK,
(uint64_t)wholedisk) == 0);
@@ -432,11 +443,16 @@ typedef struct replication_level {
#define ZPOOL_FUZZ (16 * 1024 * 1024)
/*
* N.B. For the purposes of comparing replication levels dRAID can be
* considered functionally equivilant to raidz.
*/
static boolean_t
is_raidz_mirror(replication_level_t *a, replication_level_t *b,
replication_level_t **raidz, replication_level_t **mirror)
{
if (strcmp(a->zprl_type, "raidz") == 0 &&
if ((strcmp(a->zprl_type, "raidz") == 0 ||
strcmp(a->zprl_type, "draid") == 0) &&
strcmp(b->zprl_type, "mirror") == 0) {
*raidz = a;
*mirror = b;
@@ -445,6 +461,22 @@ is_raidz_mirror(replication_level_t *a, replication_level_t *b,
return (B_FALSE);
}
/*
* Comparison for determining if dRAID and raidz where passed in either order.
*/
static boolean_t
is_raidz_draid(replication_level_t *a, replication_level_t *b)
{
if ((strcmp(a->zprl_type, "raidz") == 0 ||
strcmp(a->zprl_type, "draid") == 0) &&
(strcmp(b->zprl_type, "raidz") == 0 ||
strcmp(b->zprl_type, "draid") == 0)) {
return (B_TRUE);
}
return (B_FALSE);
}
/*
* Given a list of toplevel vdevs, return the current replication level. If
* the config is inconsistent, then NULL is returned. If 'fatal' is set, then
@@ -511,7 +543,8 @@ get_replication(nvlist_t *nvroot, boolean_t fatal)
rep.zprl_type = type;
rep.zprl_children = 0;
if (strcmp(type, VDEV_TYPE_RAIDZ) == 0) {
if (strcmp(type, VDEV_TYPE_RAIDZ) == 0 ||
strcmp(type, VDEV_TYPE_DRAID) == 0) {
verify(nvlist_lookup_uint64(nv,
ZPOOL_CONFIG_NPARITY,
&rep.zprl_parity) == 0);
@@ -677,6 +710,29 @@ get_replication(nvlist_t *nvroot, boolean_t fatal)
else
return (NULL);
}
} else if (is_raidz_draid(&lastrep, &rep)) {
/*
* Accepted raidz and draid when they can
* handle the same number of disk failures.
*/
if (lastrep.zprl_parity != rep.zprl_parity) {
if (ret != NULL)
free(ret);
ret = NULL;
if (fatal)
vdev_error(gettext(
"mismatched replication "
"level: %s and %s vdevs "
"with different "
"redundancy, %llu vs. "
"%llu are present\n"),
lastrep.zprl_type,
rep.zprl_type,
lastrep.zprl_parity,
rep.zprl_parity);
else
return (NULL);
}
} else if (strcmp(lastrep.zprl_type, rep.zprl_type) !=
0) {
if (ret != NULL)
@@ -1103,31 +1159,87 @@ is_device_in_use(nvlist_t *config, nvlist_t *nv, boolean_t force,
return (anyinuse);
}
/*
* Returns the parity level extracted from a raidz or draid type.
* If the parity cannot be determined zero is returned.
*/
static int
get_parity(const char *type)
{
long parity = 0;
const char *p;
if (strncmp(type, VDEV_TYPE_RAIDZ, strlen(VDEV_TYPE_RAIDZ)) == 0) {
p = type + strlen(VDEV_TYPE_RAIDZ);
if (*p == '\0') {
/* when unspecified default to single parity */
return (1);
} else if (*p == '0') {
/* no zero prefixes allowed */
return (0);
} else {
/* 0-3, no suffixes allowed */
char *end;
errno = 0;
parity = strtol(p, &end, 10);
if (errno != 0 || *end != '\0' ||
parity < 1 || parity > VDEV_RAIDZ_MAXPARITY) {
return (0);
}
}
} else if (strncmp(type, VDEV_TYPE_DRAID,
strlen(VDEV_TYPE_DRAID)) == 0) {
p = type + strlen(VDEV_TYPE_DRAID);
if (*p == '\0' || *p == ':') {
/* when unspecified default to single parity */
return (1);
} else if (*p == '0') {
/* no zero prefixes allowed */
return (0);
} else {
/* 0-3, allowed suffixes: '\0' or ':' */
char *end;
errno = 0;
parity = strtol(p, &end, 10);
if (errno != 0 ||
parity < 1 || parity > VDEV_DRAID_MAXPARITY ||
(*end != '\0' && *end != ':')) {
return (0);
}
}
}
return ((int)parity);
}
/*
* Assign the minimum and maximum number of devices allowed for
* the specified type. On error NULL is returned, otherwise the
* type prefix is returned (raidz, mirror, etc).
*/
static const char *
is_grouping(const char *type, int *mindev, int *maxdev)
{
if (strncmp(type, "raidz", 5) == 0) {
const char *p = type + 5;
char *end;
long nparity;
if (*p == '\0') {
nparity = 1;
} else if (*p == '0') {
return (NULL); /* no zero prefixes allowed */
} else {
errno = 0;
nparity = strtol(p, &end, 10);
if (errno != 0 || nparity < 1 || nparity >= 255 ||
*end != '\0')
return (NULL);
}
int nparity;
if (strncmp(type, VDEV_TYPE_RAIDZ, strlen(VDEV_TYPE_RAIDZ)) == 0 ||
strncmp(type, VDEV_TYPE_DRAID, strlen(VDEV_TYPE_DRAID)) == 0) {
nparity = get_parity(type);
if (nparity == 0)
return (NULL);
if (mindev != NULL)
*mindev = nparity + 1;
if (maxdev != NULL)
*maxdev = 255;
return (VDEV_TYPE_RAIDZ);
if (strncmp(type, VDEV_TYPE_RAIDZ,
strlen(VDEV_TYPE_RAIDZ)) == 0) {
return (VDEV_TYPE_RAIDZ);
} else {
return (VDEV_TYPE_DRAID);
}
}
if (maxdev != NULL)
@@ -1167,6 +1279,163 @@ is_grouping(const char *type, int *mindev, int *maxdev)
return (NULL);
}
/*
* Extract the configuration parameters encoded in the dRAID type and
* use them to generate a dRAID configuration. The expected format is:
*
* draid[<parity>][:<data><d|D>][:<children><c|C>][:<spares><s|S>]
*
* The intent is to be able to generate a good configuration when no
* additional information is provided. The only mandatory component
* of the 'type' is the 'draid' prefix. If a value is not provided
* then reasonable defaults are used. The optional components may
* appear in any order but the d/s/c suffix is required.
*
* Valid inputs:
* - data: number of data devices per group (1-255)
* - parity: number of parity blocks per group (1-3)
* - spares: number of distributed spare (0-100)
* - children: total number of devices (1-255)
*
* Examples:
* - zpool create tank draid <devices...>
* - zpool create tank draid2:8d:51c:2s <devices...>
*/
static int
draid_config_by_type(nvlist_t *nv, const char *type, uint64_t children)
{
uint64_t nparity = 1;
uint64_t nspares = 0;
uint64_t ndata = UINT64_MAX;
uint64_t ngroups = 1;
long value;
if (strncmp(type, VDEV_TYPE_DRAID, strlen(VDEV_TYPE_DRAID)) != 0)
return (EINVAL);
nparity = (uint64_t)get_parity(type);
if (nparity == 0)
return (EINVAL);
char *p = (char *)type;
while ((p = strchr(p, ':')) != NULL) {
char *end;
p = p + 1;
errno = 0;
if (!isdigit(p[0])) {
(void) fprintf(stderr, gettext("invalid dRAID "
"syntax; expected [:<number><c|d|s>] not '%s'\n"),
type);
return (EINVAL);
}
/* Expected non-zero value with c/d/s suffix */
value = strtol(p, &end, 10);
char suffix = tolower(*end);
if (errno != 0 ||
(suffix != 'c' && suffix != 'd' && suffix != 's')) {
(void) fprintf(stderr, gettext("invalid dRAID "
"syntax; expected [:<number><c|d|s>] not '%s'\n"),
type);
return (EINVAL);
}
if (suffix == 'c') {
if ((uint64_t)value != children) {
fprintf(stderr,
gettext("invalid number of dRAID children; "
"%llu required but %llu provided\n"),
(u_longlong_t)value,
(u_longlong_t)children);
return (EINVAL);
}
} else if (suffix == 'd') {
ndata = (uint64_t)value;
} else if (suffix == 's') {
nspares = (uint64_t)value;
} else {
verify(0); /* Unreachable */
}
}
/*
* When a specific number of data disks is not provided limit a
* redundancy group to 8 data disks. This value was selected to
* provide a reasonable tradeoff between capacity and performance.
*/
if (ndata == UINT64_MAX) {
if (children > nspares + nparity) {
ndata = MIN(children - nspares - nparity, 8);
} else {
fprintf(stderr, gettext("request number of "
"distributed spares %llu and parity level %llu\n"
"leaves no disks available for data\n"),
(u_longlong_t)nspares, (u_longlong_t)nparity);
return (EINVAL);
}
}
/* Verify the maximum allowed group size is never exceeded. */
if (ndata == 0 || (ndata + nparity > children - nspares)) {
fprintf(stderr, gettext("requested number of dRAID data "
"disks per group %llu is too high,\nat most %llu disks "
"are available for data\n"), (u_longlong_t)ndata,
(u_longlong_t)(children - nspares - nparity));
return (EINVAL);
}
if (nparity == 0 || nparity > VDEV_DRAID_MAXPARITY) {
fprintf(stderr,
gettext("invalid dRAID parity level %llu; must be "
"between 1 and %d\n"), (u_longlong_t)nparity,
VDEV_DRAID_MAXPARITY);
return (EINVAL);
}
/*
* Verify the requested number of spares can be satisfied.
* An arbitrary limit of 100 distributed spares is applied.
*/
if (nspares > 100 || nspares > (children - (ndata + nparity))) {
fprintf(stderr,
gettext("invalid number of dRAID spares %llu; additional "
"disks would be required\n"), (u_longlong_t)nspares);
return (EINVAL);
}
/* Verify the requested number children is sufficient. */
if (children < (ndata + nparity + nspares)) {
fprintf(stderr, gettext("%llu disks were provided, but at "
"least %llu disks are required for this config\n"),
(u_longlong_t)children,
(u_longlong_t)(ndata + nparity + nspares));
}
if (children > VDEV_DRAID_MAX_CHILDREN) {
fprintf(stderr, gettext("%llu disks were provided, but "
"dRAID only supports up to %u disks"),
(u_longlong_t)children, VDEV_DRAID_MAX_CHILDREN);
}
/*
* Calculate the minimum number of groups required to fill a slice.
* This is the LCM of the stripe width (ndata + nparity) and the
* number of data drives (children - nspares).
*/
while (ngroups * (ndata + nparity) % (children - nspares) != 0)
ngroups++;
/* Store the basic dRAID configuration. */
fnvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY, nparity);
fnvlist_add_uint64(nv, ZPOOL_CONFIG_DRAID_NDATA, ndata);
fnvlist_add_uint64(nv, ZPOOL_CONFIG_DRAID_NSPARES, nspares);
fnvlist_add_uint64(nv, ZPOOL_CONFIG_DRAID_NGROUPS, ngroups);
return (0);
}
/*
* Construct a syntactically valid vdev specification,
* and ensure that all devices and files exist and can be opened.
@@ -1178,8 +1447,8 @@ construct_spec(nvlist_t *props, int argc, char **argv)
{
nvlist_t *nvroot, *nv, **top, **spares, **l2cache;
int t, toplevels, mindev, maxdev, nspares, nlogs, nl2cache;
const char *type;
uint64_t is_log, is_special, is_dedup;
const char *type, *fulltype;
boolean_t is_log, is_special, is_dedup, is_spare;
boolean_t seen_logs;
top = NULL;
@@ -1189,18 +1458,20 @@ construct_spec(nvlist_t *props, int argc, char **argv)
nspares = 0;
nlogs = 0;
nl2cache = 0;
is_log = is_special = is_dedup = B_FALSE;
is_log = is_special = is_dedup = is_spare = B_FALSE;
seen_logs = B_FALSE;
nvroot = NULL;
while (argc > 0) {
fulltype = argv[0];
nv = NULL;
/*
* If it's a mirror or raidz, the subsequent arguments are
* its leaves -- until we encounter the next mirror or raidz.
* If it's a mirror, raidz, or draid the subsequent arguments
* are its leaves -- until we encounter the next mirror,
* raidz or draid.
*/
if ((type = is_grouping(argv[0], &mindev, &maxdev)) != NULL) {
if ((type = is_grouping(fulltype, &mindev, &maxdev)) != NULL) {
nvlist_t **child = NULL;
int c, children = 0;
@@ -1212,6 +1483,7 @@ construct_spec(nvlist_t *props, int argc, char **argv)
"specified only once\n"));
goto spec_out;
}
is_spare = B_TRUE;
is_log = is_special = is_dedup = B_FALSE;
}
@@ -1225,8 +1497,7 @@ construct_spec(nvlist_t *props, int argc, char **argv)
}
seen_logs = B_TRUE;
is_log = B_TRUE;
is_special = B_FALSE;
is_dedup = B_FALSE;
is_special = is_dedup = is_spare = B_FALSE;
argc--;
argv++;
/*
@@ -1238,8 +1509,7 @@ construct_spec(nvlist_t *props, int argc, char **argv)
if (strcmp(type, VDEV_ALLOC_BIAS_SPECIAL) == 0) {
is_special = B_TRUE;
is_log = B_FALSE;
is_dedup = B_FALSE;
is_log = is_dedup = is_spare = B_FALSE;
argc--;
argv++;
continue;
@@ -1247,8 +1517,7 @@ construct_spec(nvlist_t *props, int argc, char **argv)
if (strcmp(type, VDEV_ALLOC_BIAS_DEDUP) == 0) {
is_dedup = B_TRUE;
is_log = B_FALSE;
is_special = B_FALSE;
is_log = is_special = is_spare = B_FALSE;
argc--;
argv++;
continue;
@@ -1262,7 +1531,8 @@ construct_spec(nvlist_t *props, int argc, char **argv)
"specified only once\n"));
goto spec_out;
}
is_log = is_special = is_dedup = B_FALSE;
is_log = is_special = B_FALSE;
is_dedup = is_spare = B_FALSE;
}
if (is_log || is_special || is_dedup) {
@@ -1280,13 +1550,15 @@ construct_spec(nvlist_t *props, int argc, char **argv)
for (c = 1; c < argc; c++) {
if (is_grouping(argv[c], NULL, NULL) != NULL)
break;
children++;
child = realloc(child,
children * sizeof (nvlist_t *));
if (child == NULL)
zpool_no_memory();
if ((nv = make_leaf_vdev(props, argv[c],
B_FALSE)) == NULL) {
!(is_log || is_special || is_dedup ||
is_spare))) == NULL) {
for (c = 0; c < children - 1; c++)
nvlist_free(child[c]);
free(child);
@@ -1335,10 +1607,11 @@ construct_spec(nvlist_t *props, int argc, char **argv)
type) == 0);
verify(nvlist_add_uint64(nv,
ZPOOL_CONFIG_IS_LOG, is_log) == 0);
if (is_log)
if (is_log) {
verify(nvlist_add_string(nv,
ZPOOL_CONFIG_ALLOCATION_BIAS,
VDEV_ALLOC_BIAS_LOG) == 0);
}
if (is_special) {
verify(nvlist_add_string(nv,
ZPOOL_CONFIG_ALLOCATION_BIAS,
@@ -1354,6 +1627,15 @@ construct_spec(nvlist_t *props, int argc, char **argv)
ZPOOL_CONFIG_NPARITY,
mindev - 1) == 0);
}
if (strcmp(type, VDEV_TYPE_DRAID) == 0) {
if (draid_config_by_type(nv,
fulltype, children) != 0) {
for (c = 0; c < children; c++)
nvlist_free(child[c]);
free(child);
goto spec_out;
}
}
verify(nvlist_add_nvlist_array(nv,
ZPOOL_CONFIG_CHILDREN, child,
children) == 0);
@@ -1367,12 +1649,19 @@ construct_spec(nvlist_t *props, int argc, char **argv)
* We have a device. Pass off to make_leaf_vdev() to
* construct the appropriate nvlist describing the vdev.
*/
if ((nv = make_leaf_vdev(props, argv[0],
is_log)) == NULL)
if ((nv = make_leaf_vdev(props, argv[0], !(is_log ||
is_special || is_dedup || is_spare))) == NULL)
goto spec_out;
if (is_log)
verify(nvlist_add_uint64(nv,
ZPOOL_CONFIG_IS_LOG, is_log) == 0);
if (is_log) {
verify(nvlist_add_string(nv,
ZPOOL_CONFIG_ALLOCATION_BIAS,
VDEV_ALLOC_BIAS_LOG) == 0);
nlogs++;
}
if (is_special) {
verify(nvlist_add_string(nv,
ZPOOL_CONFIG_ALLOCATION_BIAS,