mirror_zfs/module/zcommon/zpool_prop.c
Matthew Ahrens 050d720c43 Remove dedupditto functionality
If dedup is in use, the `dedupditto` property can be set, causing ZFS to
keep an extra copy of data that is referenced many times (>100x).  The
idea was that this data is more important than other data and thus we
want to be really sure that it is not lost if the disk experiences a
small amount of random corruption.

ZFS (and system administrators) rely on the pool-level redundancy to
protect their data (e.g. mirroring or RAIDZ).  Since the user/sysadmin
doesn't have control over what data will be offered extra redundancy by
dedupditto, this extra redundancy is not very useful.  The bulk of the
data is still vulnerable to loss based on the pool-level redundancy.
For example, if particle strikes corrupt 0.1% of blocks, you will either
be saved by mirror/raidz, or you will be sad.  This is true even if
dedupditto saved another 0.01% of blocks from being corrupted.

Therefore, the dedupditto functionality is rarely enabled (i.e. the
property is rarely set), and it fulfills its promise of increased
redundancy even more rarely.

Additionally, this feature does not work as advertised (on existing
releases), because scrub/resilver did not repair the extra (dedupditto)
copy (see https://github.com/zfsonlinux/zfs/pull/8270).

In summary, this seldom-used feature doesn't work, and even if it did it
wouldn't provide useful data protection.  It has a non-trivial
maintenance burden (again see https://github.com/zfsonlinux/zfs/pull/8270).

We should remove the dedupditto functionality.  For backwards
compatibility with the existing CLI, "zpool set dedupditto" will still
"succeed" (exit code zero), but won't have any effect.  For backwards
compatibility with existing pools that had dedupditto enabled at some
point, the code will still be able to understand dedupditto blocks and
free them when appropriate.  However, ZFS won't write any new dedupditto
blocks.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Alek Pinchuk <apinchuk@datto.com>
Issue #8270 
Closes #8310
2019-06-19 14:54:02 -07:00

275 lines
8.5 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
* Copyright (c) 2012, 2018 by Delphix. All rights reserved.
*/
#include <sys/zio.h>
#include <sys/spa.h>
#include <sys/zfs_acl.h>
#include <sys/zfs_ioctl.h>
#include <sys/fs/zfs.h>
#include "zfs_prop.h"
#if !defined(_KERNEL)
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#endif
static zprop_desc_t zpool_prop_table[ZPOOL_NUM_PROPS];
zprop_desc_t *
zpool_prop_get_table(void)
{
return (zpool_prop_table);
}
void
zpool_prop_init(void)
{
static zprop_index_t boolean_table[] = {
{ "off", 0},
{ "on", 1},
{ NULL }
};
static zprop_index_t failuremode_table[] = {
{ "wait", ZIO_FAILURE_MODE_WAIT },
{ "continue", ZIO_FAILURE_MODE_CONTINUE },
{ "panic", ZIO_FAILURE_MODE_PANIC },
{ NULL }
};
/* string properties */
zprop_register_string(ZPOOL_PROP_ALTROOT, "altroot", NULL, PROP_DEFAULT,
ZFS_TYPE_POOL, "<path>", "ALTROOT");
zprop_register_string(ZPOOL_PROP_BOOTFS, "bootfs", NULL, PROP_DEFAULT,
ZFS_TYPE_POOL, "<filesystem>", "BOOTFS");
zprop_register_string(ZPOOL_PROP_CACHEFILE, "cachefile", NULL,
PROP_DEFAULT, ZFS_TYPE_POOL, "<file> | none", "CACHEFILE");
zprop_register_string(ZPOOL_PROP_COMMENT, "comment", NULL,
PROP_DEFAULT, ZFS_TYPE_POOL, "<comment-string>", "COMMENT");
/* readonly number properties */
zprop_register_number(ZPOOL_PROP_SIZE, "size", 0, PROP_READONLY,
ZFS_TYPE_POOL, "<size>", "SIZE");
zprop_register_number(ZPOOL_PROP_FREE, "free", 0, PROP_READONLY,
ZFS_TYPE_POOL, "<size>", "FREE");
zprop_register_number(ZPOOL_PROP_FREEING, "freeing", 0, PROP_READONLY,
ZFS_TYPE_POOL, "<size>", "FREEING");
zprop_register_number(ZPOOL_PROP_CHECKPOINT, "checkpoint", 0,
PROP_READONLY, ZFS_TYPE_POOL, "<size>", "CKPOINT");
zprop_register_number(ZPOOL_PROP_LEAKED, "leaked", 0, PROP_READONLY,
ZFS_TYPE_POOL, "<size>", "LEAKED");
zprop_register_number(ZPOOL_PROP_ALLOCATED, "allocated", 0,
PROP_READONLY, ZFS_TYPE_POOL, "<size>", "ALLOC");
zprop_register_number(ZPOOL_PROP_EXPANDSZ, "expandsize", 0,
PROP_READONLY, ZFS_TYPE_POOL, "<size>", "EXPANDSZ");
zprop_register_number(ZPOOL_PROP_FRAGMENTATION, "fragmentation", 0,
PROP_READONLY, ZFS_TYPE_POOL, "<percent>", "FRAG");
zprop_register_number(ZPOOL_PROP_CAPACITY, "capacity", 0, PROP_READONLY,
ZFS_TYPE_POOL, "<size>", "CAP");
zprop_register_number(ZPOOL_PROP_GUID, "guid", 0, PROP_READONLY,
ZFS_TYPE_POOL, "<guid>", "GUID");
zprop_register_number(ZPOOL_PROP_LOAD_GUID, "load_guid", 0,
PROP_READONLY, ZFS_TYPE_POOL, "<load_guid>", "LOAD_GUID");
zprop_register_number(ZPOOL_PROP_HEALTH, "health", 0, PROP_READONLY,
ZFS_TYPE_POOL, "<state>", "HEALTH");
zprop_register_number(ZPOOL_PROP_DEDUPRATIO, "dedupratio", 0,
PROP_READONLY, ZFS_TYPE_POOL, "<1.00x or higher if deduped>",
"DEDUP");
/* default number properties */
zprop_register_number(ZPOOL_PROP_VERSION, "version", SPA_VERSION,
PROP_DEFAULT, ZFS_TYPE_POOL, "<version>", "VERSION");
zprop_register_number(ZPOOL_PROP_ASHIFT, "ashift", 0, PROP_DEFAULT,
ZFS_TYPE_POOL, "<ashift, 9-16, or 0=default>", "ASHIFT");
/* default index (boolean) properties */
zprop_register_index(ZPOOL_PROP_DELEGATION, "delegation", 1,
PROP_DEFAULT, ZFS_TYPE_POOL, "on | off", "DELEGATION",
boolean_table);
zprop_register_index(ZPOOL_PROP_AUTOREPLACE, "autoreplace", 0,
PROP_DEFAULT, ZFS_TYPE_POOL, "on | off", "REPLACE", boolean_table);
zprop_register_index(ZPOOL_PROP_LISTSNAPS, "listsnapshots", 0,
PROP_DEFAULT, ZFS_TYPE_POOL, "on | off", "LISTSNAPS",
boolean_table);
zprop_register_index(ZPOOL_PROP_AUTOEXPAND, "autoexpand", 0,
PROP_DEFAULT, ZFS_TYPE_POOL, "on | off", "EXPAND", boolean_table);
zprop_register_index(ZPOOL_PROP_READONLY, "readonly", 0,
PROP_DEFAULT, ZFS_TYPE_POOL, "on | off", "RDONLY", boolean_table);
zprop_register_index(ZPOOL_PROP_MULTIHOST, "multihost", 0,
PROP_DEFAULT, ZFS_TYPE_POOL, "on | off", "MULTIHOST",
boolean_table);
/* default index properties */
zprop_register_index(ZPOOL_PROP_FAILUREMODE, "failmode",
ZIO_FAILURE_MODE_WAIT, PROP_DEFAULT, ZFS_TYPE_POOL,
"wait | continue | panic", "FAILMODE", failuremode_table);
zprop_register_index(ZPOOL_PROP_AUTOTRIM, "autotrim",
SPA_AUTOTRIM_OFF, PROP_DEFAULT, ZFS_TYPE_POOL,
"on | off", "AUTOTRIM", boolean_table);
/* hidden properties */
zprop_register_hidden(ZPOOL_PROP_NAME, "name", PROP_TYPE_STRING,
PROP_READONLY, ZFS_TYPE_POOL, "NAME");
zprop_register_hidden(ZPOOL_PROP_MAXBLOCKSIZE, "maxblocksize",
PROP_TYPE_NUMBER, PROP_READONLY, ZFS_TYPE_POOL, "MAXBLOCKSIZE");
zprop_register_hidden(ZPOOL_PROP_TNAME, "tname", PROP_TYPE_STRING,
PROP_ONETIME, ZFS_TYPE_POOL, "TNAME");
zprop_register_hidden(ZPOOL_PROP_MAXDNODESIZE, "maxdnodesize",
PROP_TYPE_NUMBER, PROP_READONLY, ZFS_TYPE_POOL, "MAXDNODESIZE");
zprop_register_hidden(ZPOOL_PROP_DEDUPDITTO, "dedupditto",
PROP_TYPE_NUMBER, PROP_DEFAULT, ZFS_TYPE_POOL, "DEDUPDITTO");
}
/*
* Given a property name and its type, returns the corresponding property ID.
*/
zpool_prop_t
zpool_name_to_prop(const char *propname)
{
return (zprop_name_to_prop(propname, ZFS_TYPE_POOL));
}
/*
* Given a pool property ID, returns the corresponding name.
* Assuming the pool propety ID is valid.
*/
const char *
zpool_prop_to_name(zpool_prop_t prop)
{
return (zpool_prop_table[prop].pd_name);
}
zprop_type_t
zpool_prop_get_type(zpool_prop_t prop)
{
return (zpool_prop_table[prop].pd_proptype);
}
boolean_t
zpool_prop_readonly(zpool_prop_t prop)
{
return (zpool_prop_table[prop].pd_attr == PROP_READONLY);
}
boolean_t
zpool_prop_setonce(zpool_prop_t prop)
{
return (zpool_prop_table[prop].pd_attr == PROP_ONETIME);
}
const char *
zpool_prop_default_string(zpool_prop_t prop)
{
return (zpool_prop_table[prop].pd_strdefault);
}
uint64_t
zpool_prop_default_numeric(zpool_prop_t prop)
{
return (zpool_prop_table[prop].pd_numdefault);
}
/*
* Returns true if this is a valid feature@ property.
*/
boolean_t
zpool_prop_feature(const char *name)
{
static const char *prefix = "feature@";
return (strncmp(name, prefix, strlen(prefix)) == 0);
}
/*
* Returns true if this is a valid unsupported@ property.
*/
boolean_t
zpool_prop_unsupported(const char *name)
{
static const char *prefix = "unsupported@";
return (strncmp(name, prefix, strlen(prefix)) == 0);
}
int
zpool_prop_string_to_index(zpool_prop_t prop, const char *string,
uint64_t *index)
{
return (zprop_string_to_index(prop, string, index, ZFS_TYPE_POOL));
}
int
zpool_prop_index_to_string(zpool_prop_t prop, uint64_t index,
const char **string)
{
return (zprop_index_to_string(prop, index, string, ZFS_TYPE_POOL));
}
uint64_t
zpool_prop_random_value(zpool_prop_t prop, uint64_t seed)
{
return (zprop_random_value(prop, seed, ZFS_TYPE_POOL));
}
#ifndef _KERNEL
const char *
zpool_prop_values(zpool_prop_t prop)
{
return (zpool_prop_table[prop].pd_values);
}
const char *
zpool_prop_column_name(zpool_prop_t prop)
{
return (zpool_prop_table[prop].pd_colname);
}
boolean_t
zpool_prop_align_right(zpool_prop_t prop)
{
return (zpool_prop_table[prop].pd_rightalign);
}
#endif
#if defined(_KERNEL)
/* zpool property functions */
EXPORT_SYMBOL(zpool_prop_init);
EXPORT_SYMBOL(zpool_prop_get_type);
EXPORT_SYMBOL(zpool_prop_get_table);
/* Pool property functions shared between libzfs and kernel. */
EXPORT_SYMBOL(zpool_name_to_prop);
EXPORT_SYMBOL(zpool_prop_to_name);
EXPORT_SYMBOL(zpool_prop_default_string);
EXPORT_SYMBOL(zpool_prop_default_numeric);
EXPORT_SYMBOL(zpool_prop_readonly);
EXPORT_SYMBOL(zpool_prop_feature);
EXPORT_SYMBOL(zpool_prop_unsupported);
EXPORT_SYMBOL(zpool_prop_index_to_string);
EXPORT_SYMBOL(zpool_prop_string_to_index);
#endif