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This feature allows disks to be added one at a time to a RAID-Z group, expanding its capacity incrementally. This feature is especially useful for small pools (typically with only one RAID-Z group), where there isn't sufficient hardware to add capacity by adding a whole new RAID-Z group (typically doubling the number of disks). == Initiating expansion == A new device (disk) can be attached to an existing RAIDZ vdev, by running `zpool attach POOL raidzP-N NEW_DEVICE`, e.g. `zpool attach tank raidz2-0 sda`. The new device will become part of the RAIDZ group. A "raidz expansion" will be initiated, and the new device will contribute additional space to the RAIDZ group once the expansion completes. The `feature@raidz_expansion` on-disk feature flag must be `enabled` to initiate an expansion, and it remains `active` for the life of the pool. In other words, pools with expanded RAIDZ vdevs can not be imported by older releases of the ZFS software. == During expansion == The expansion entails reading all allocated space from existing disks in the RAIDZ group, and rewriting it to the new disks in the RAIDZ group (including the newly added device). The expansion progress can be monitored with `zpool status`. Data redundancy is maintained during (and after) the expansion. If a disk fails while the expansion is in progress, the expansion pauses until the health of the RAIDZ vdev is restored (e.g. by replacing the failed disk and waiting for reconstruction to complete). The pool remains accessible during expansion. Following a reboot or export/import, the expansion resumes where it left off. == After expansion == When the expansion completes, the additional space is available for use, and is reflected in the `available` zfs property (as seen in `zfs list`, `df`, etc). Expansion does not change the number of failures that can be tolerated without data loss (e.g. a RAIDZ2 is still a RAIDZ2 even after expansion). A RAIDZ vdev can be expanded multiple times. After the expansion completes, old blocks remain with their old data-to-parity ratio (e.g. 5-wide RAIDZ2, has 3 data to 2 parity), but distributed among the larger set of disks. New blocks will be written with the new data-to-parity ratio (e.g. a 5-wide RAIDZ2 which has been expanded once to 6-wide, has 4 data to 2 parity). However, the RAIDZ vdev's "assumed parity ratio" does not change, so slightly less space than is expected may be reported for newly-written blocks, according to `zfs list`, `df`, `ls -s`, and similar tools. Sponsored-by: The FreeBSD Foundation Sponsored-by: iXsystems, Inc. Sponsored-by: vStack Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Mark Maybee <mark.maybee@delphix.com> Authored-by: Matthew Ahrens <mahrens@delphix.com> Contributions-by: Fedor Uporov <fuporov.vstack@gmail.com> Contributions-by: Stuart Maybee <stuart.maybee@comcast.net> Contributions-by: Thorsten Behrens <tbehrens@outlook.com> Contributions-by: Fmstrat <nospam@nowsci.com> Contributions-by: Don Brady <dev.fs.zfs@gmail.com> Signed-off-by: Don Brady <dev.fs.zfs@gmail.com> Closes #15022
115 lines
3.5 KiB
C
115 lines
3.5 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 https://opensource.org/licenses/CDDL-1.0.
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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) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
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* Copyright (c) 2012, 2019 by Delphix. All rights reserved.
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*/
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#ifndef _SYS_ZFS_DEBUG_H
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#define _SYS_ZFS_DEBUG_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef TRUE
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#define TRUE 1
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#endif
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#ifndef FALSE
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#define FALSE 0
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#endif
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extern int zfs_flags;
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extern int zfs_recover;
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extern int zfs_free_leak_on_eio;
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extern int zfs_dbgmsg_enable;
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#define ZFS_DEBUG_DPRINTF (1 << 0)
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#define ZFS_DEBUG_DBUF_VERIFY (1 << 1)
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#define ZFS_DEBUG_DNODE_VERIFY (1 << 2)
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#define ZFS_DEBUG_SNAPNAMES (1 << 3)
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#define ZFS_DEBUG_MODIFY (1 << 4)
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/* 1<<5 was previously used, try not to reuse */
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#define ZFS_DEBUG_ZIO_FREE (1 << 6)
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#define ZFS_DEBUG_HISTOGRAM_VERIFY (1 << 7)
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#define ZFS_DEBUG_METASLAB_VERIFY (1 << 8)
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#define ZFS_DEBUG_SET_ERROR (1 << 9)
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#define ZFS_DEBUG_INDIRECT_REMAP (1 << 10)
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#define ZFS_DEBUG_TRIM (1 << 11)
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#define ZFS_DEBUG_LOG_SPACEMAP (1 << 12)
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#define ZFS_DEBUG_METASLAB_ALLOC (1 << 13)
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#define ZFS_DEBUG_BRT (1 << 14)
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#define ZFS_DEBUG_RAIDZ_RECONSTRUCT (1 << 15)
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extern void __set_error(const char *file, const char *func, int line, int err);
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extern void __zfs_dbgmsg(char *buf);
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extern void __dprintf(boolean_t dprint, const char *file, const char *func,
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int line, const char *fmt, ...) __attribute__((format(printf, 5, 6)));
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/*
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* Some general principles for using zfs_dbgmsg():
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* 1. We don't want to pollute the log with typically-irrelevant messages,
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* so don't print too many messages in the "normal" code path - O(1)
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* per txg.
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* 2. We want to know for sure what happened, so make the message specific
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* (e.g. *which* thing am I operating on).
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* 3. Do print a message when something unusual or unexpected happens
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* (e.g. error cases).
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* 4. Print a message when making user-initiated on-disk changes.
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*
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* Note that besides principle 1, another reason that we don't want to
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* use zfs_dbgmsg in high-frequency routines is the potential impact
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* that it can have on performance.
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*/
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#define zfs_dbgmsg(...) \
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if (zfs_dbgmsg_enable) \
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__dprintf(B_FALSE, __FILE__, __func__, __LINE__, __VA_ARGS__)
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#ifdef ZFS_DEBUG
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/*
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* To enable this:
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*
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* $ echo 1 >/sys/module/zfs/parameters/zfs_flags
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*/
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#define dprintf(...) \
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if (zfs_flags & ZFS_DEBUG_DPRINTF) \
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__dprintf(B_TRUE, __FILE__, __func__, __LINE__, __VA_ARGS__)
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#else
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#define dprintf(...) ((void)0)
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#endif /* ZFS_DEBUG */
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extern void zfs_panic_recover(const char *fmt, ...);
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extern void zfs_dbgmsg_init(void);
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extern void zfs_dbgmsg_fini(void);
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#ifndef _KERNEL
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extern int dprintf_find_string(const char *string);
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extern void zfs_dbgmsg_print(const char *tag);
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif /* _SYS_ZFS_DEBUG_H */
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