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619f097693
PROBLEM
========
The first access to a block incurs a performance penalty on some platforms
(e.g. AWS's EBS, VMware VMDKs). Therefore we recommend that volumes are
"thick provisioned", where supported by the platform (VMware). This can
create a large delay in getting a new virtual machines up and running (or
adding storage to an existing Engine). If the thick provision step is
omitted, write performance will be suboptimal until all blocks on the LUN
have been written.
SOLUTION
=========
This feature introduces a way to 'initialize' the disks at install or in the
background to make sure we don't incur this first read penalty.
When an entire LUN is added to ZFS, we make all space available immediately,
and allow ZFS to find unallocated space and zero it out. This works with
concurrent writes to arbitrary offsets, ensuring that we don't zero out
something that has been (or is in the middle of being) written. This scheme
can also be applied to existing pools (affecting only free regions on the
vdev). Detailed design:
- new subcommand:zpool initialize [-cs] <pool> [<vdev> ...]
- start, suspend, or cancel initialization
- Creates new open-context thread for each vdev
- Thread iterates through all metaslabs in this vdev
- Each metaslab:
- select a metaslab
- load the metaslab
- mark the metaslab as being zeroed
- walk all free ranges within that metaslab and translate
them to ranges on the leaf vdev
- issue a "zeroing" I/O on the leaf vdev that corresponds to
a free range on the metaslab we're working on
- continue until all free ranges for this metaslab have been
"zeroed"
- reset/unmark the metaslab being zeroed
- if more metaslabs exist, then repeat above tasks.
- if no more metaslabs, then we're done.
- progress for the initialization is stored on-disk in the vdev’s
leaf zap object. The following information is stored:
- the last offset that has been initialized
- the state of the initialization process (i.e. active,
suspended, or canceled)
- the start time for the initialization
- progress is reported via the zpool status command and shows
information for each of the vdevs that are initializing
Porting notes:
- Added zfs_initialize_value module parameter to set the pattern
written by "zpool initialize".
- Added zfs_vdev_{initializing,removal}_{min,max}_active module options.
Authored by: George Wilson <george.wilson@delphix.com>
Reviewed by: John Wren Kennedy <john.kennedy@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: loli10K <ezomori.nozomu@gmail.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Richard Lowe <richlowe@richlowe.net>
Signed-off-by: Tim Chase <tim@chase2k.com>
Ported-by: Tim Chase <tim@chase2k.com>
OpenZFS-issue: https://www.illumos.org/issues/9102
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/c3963210eb
Closes #8230
126 lines
4.1 KiB
C
126 lines
4.1 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2012, 2017 by Delphix. All rights reserved.
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* Copyright (c) 2017 Datto Inc.
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* Copyright 2017 RackTop Systems.
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* Copyright (c) 2017 Open-E, Inc. All Rights Reserved.
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*/
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#ifndef _LIBZFS_CORE_H
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#define _LIBZFS_CORE_H
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#include <libnvpair.h>
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#include <sys/param.h>
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#include <sys/types.h>
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#include <sys/fs/zfs.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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int libzfs_core_init(void);
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void libzfs_core_fini(void);
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/*
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* NB: this type should be kept binary compatible with dmu_objset_type_t.
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*/
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enum lzc_dataset_type {
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LZC_DATSET_TYPE_ZFS = 2,
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LZC_DATSET_TYPE_ZVOL
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};
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int lzc_remap(const char *fsname);
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int lzc_snapshot(nvlist_t *, nvlist_t *, nvlist_t **);
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int lzc_create(const char *, enum lzc_dataset_type, nvlist_t *, uint8_t *,
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uint_t);
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int lzc_clone(const char *, const char *, nvlist_t *);
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int lzc_promote(const char *, char *, int);
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int lzc_destroy_snaps(nvlist_t *, boolean_t, nvlist_t **);
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int lzc_bookmark(nvlist_t *, nvlist_t **);
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int lzc_get_bookmarks(const char *, nvlist_t *, nvlist_t **);
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int lzc_destroy_bookmarks(nvlist_t *, nvlist_t **);
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int lzc_load_key(const char *, boolean_t, uint8_t *, uint_t);
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int lzc_unload_key(const char *);
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int lzc_change_key(const char *, uint64_t, nvlist_t *, uint8_t *, uint_t);
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int lzc_initialize(const char *, pool_initialize_func_t, nvlist_t *,
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nvlist_t **);
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int lzc_snaprange_space(const char *, const char *, uint64_t *);
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int lzc_hold(nvlist_t *, int, nvlist_t **);
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int lzc_release(nvlist_t *, nvlist_t **);
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int lzc_get_holds(const char *, nvlist_t **);
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enum lzc_send_flags {
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LZC_SEND_FLAG_EMBED_DATA = 1 << 0,
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LZC_SEND_FLAG_LARGE_BLOCK = 1 << 1,
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LZC_SEND_FLAG_COMPRESS = 1 << 2,
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LZC_SEND_FLAG_RAW = 1 << 3,
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};
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int lzc_send(const char *, const char *, int, enum lzc_send_flags);
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int lzc_send_resume(const char *, const char *, int,
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enum lzc_send_flags, uint64_t, uint64_t);
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int lzc_send_space(const char *, const char *, enum lzc_send_flags, uint64_t *);
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struct dmu_replay_record;
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int lzc_receive(const char *, nvlist_t *, const char *, boolean_t, boolean_t,
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int);
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int lzc_receive_resumable(const char *, nvlist_t *, const char *, boolean_t,
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boolean_t, int);
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int lzc_receive_with_header(const char *, nvlist_t *, const char *, boolean_t,
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boolean_t, boolean_t, int, const struct dmu_replay_record *);
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int lzc_receive_one(const char *, nvlist_t *, const char *, boolean_t,
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boolean_t, boolean_t, int, const struct dmu_replay_record *, int,
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uint64_t *, uint64_t *, uint64_t *, nvlist_t **);
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int lzc_receive_with_cmdprops(const char *, nvlist_t *, nvlist_t *,
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uint8_t *, uint_t, const char *, boolean_t, boolean_t, boolean_t, int,
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const struct dmu_replay_record *, int, uint64_t *, uint64_t *,
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uint64_t *, nvlist_t **);
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boolean_t lzc_exists(const char *);
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int lzc_rollback(const char *, char *, int);
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int lzc_rollback_to(const char *, const char *);
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int lzc_rename(const char *, const char *);
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int lzc_destroy(const char *);
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int lzc_channel_program(const char *, const char *, uint64_t,
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uint64_t, nvlist_t *, nvlist_t **);
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int lzc_channel_program_nosync(const char *, const char *, uint64_t,
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uint64_t, nvlist_t *, nvlist_t **);
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int lzc_sync(const char *, nvlist_t *, nvlist_t **);
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int lzc_reopen(const char *, boolean_t);
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int lzc_pool_checkpoint(const char *);
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int lzc_pool_checkpoint_discard(const char *);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _LIBZFS_CORE_H */
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