mirror_zfs/include/sys/uberblock_impl.h
Don Brady 5caeef02fa
RAID-Z expansion feature
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
2023-11-08 10:19:41 -08:00

181 lines
6.3 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 https://opensource.org/licenses/CDDL-1.0.
* 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) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2016, 2017 by Delphix. All rights reserved.
*/
#ifndef _SYS_UBERBLOCK_IMPL_H
#define _SYS_UBERBLOCK_IMPL_H
#include <sys/uberblock.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
* The uberblock version is incremented whenever an incompatible on-disk
* format change is made to the SPA, DMU, or ZAP.
*
* Note: the first two fields should never be moved. When a storage pool
* is opened, the uberblock must be read off the disk before the version
* can be checked. If the ub_version field is moved, we may not detect
* version mismatch. If the ub_magic field is moved, applications that
* expect the magic number in the first word won't work.
*/
#define UBERBLOCK_MAGIC 0x00bab10c /* oo-ba-bloc! */
#define UBERBLOCK_SHIFT 10 /* up to 1K */
#define MMP_MAGIC 0xa11cea11 /* all-see-all */
#define MMP_INTERVAL_VALID_BIT 0x01
#define MMP_SEQ_VALID_BIT 0x02
#define MMP_FAIL_INT_VALID_BIT 0x04
#define MMP_VALID(ubp) (ubp->ub_magic == UBERBLOCK_MAGIC && \
ubp->ub_mmp_magic == MMP_MAGIC)
#define MMP_INTERVAL_VALID(ubp) (MMP_VALID(ubp) && (ubp->ub_mmp_config & \
MMP_INTERVAL_VALID_BIT))
#define MMP_SEQ_VALID(ubp) (MMP_VALID(ubp) && (ubp->ub_mmp_config & \
MMP_SEQ_VALID_BIT))
#define MMP_FAIL_INT_VALID(ubp) (MMP_VALID(ubp) && (ubp->ub_mmp_config & \
MMP_FAIL_INT_VALID_BIT))
#define MMP_INTERVAL(ubp) ((ubp->ub_mmp_config & 0x00000000FFFFFF00) \
>> 8)
#define MMP_SEQ(ubp) ((ubp->ub_mmp_config & 0x0000FFFF00000000) \
>> 32)
#define MMP_FAIL_INT(ubp) ((ubp->ub_mmp_config & 0xFFFF000000000000) \
>> 48)
#define MMP_INTERVAL_SET(write) \
(((uint64_t)(write & 0xFFFFFF) << 8) | MMP_INTERVAL_VALID_BIT)
#define MMP_SEQ_SET(seq) \
(((uint64_t)(seq & 0xFFFF) << 32) | MMP_SEQ_VALID_BIT)
#define MMP_FAIL_INT_SET(fail) \
(((uint64_t)(fail & 0xFFFF) << 48) | MMP_FAIL_INT_VALID_BIT)
/*
* RAIDZ expansion reflow information.
*
* 64 56 48 40 32 24 16 8 0
* +-------+-------+-------+-------+-------+-------+-------+-------+
* |Scratch | Reflow |
* | State | Offset |
* +-------+-------+-------+-------+-------+-------+-------+-------+
*/
typedef enum raidz_reflow_scratch_state {
RRSS_SCRATCH_NOT_IN_USE = 0,
RRSS_SCRATCH_VALID,
RRSS_SCRATCH_INVALID_SYNCED,
RRSS_SCRATCH_INVALID_SYNCED_ON_IMPORT,
RRSS_SCRATCH_INVALID_SYNCED_REFLOW
} raidz_reflow_scratch_state_t;
#define RRSS_GET_OFFSET(ub) \
BF64_GET_SB((ub)->ub_raidz_reflow_info, 0, 55, SPA_MINBLOCKSHIFT, 0)
#define RRSS_SET_OFFSET(ub, x) \
BF64_SET_SB((ub)->ub_raidz_reflow_info, 0, 55, SPA_MINBLOCKSHIFT, 0, x)
#define RRSS_GET_STATE(ub) \
BF64_GET((ub)->ub_raidz_reflow_info, 55, 9)
#define RRSS_SET_STATE(ub, x) \
BF64_SET((ub)->ub_raidz_reflow_info, 55, 9, x)
#define RAIDZ_REFLOW_SET(ub, state, offset) do { \
(ub)->ub_raidz_reflow_info = 0; \
RRSS_SET_OFFSET(ub, offset); \
RRSS_SET_STATE(ub, state); \
} while (0)
struct uberblock {
uint64_t ub_magic; /* UBERBLOCK_MAGIC */
uint64_t ub_version; /* SPA_VERSION */
uint64_t ub_txg; /* txg of last sync */
uint64_t ub_guid_sum; /* sum of all vdev guids */
uint64_t ub_timestamp; /* UTC time of last sync */
blkptr_t ub_rootbp; /* MOS objset_phys_t */
/* highest SPA_VERSION supported by software that wrote this txg */
uint64_t ub_software_version;
/* Maybe missing in uberblocks we read, but always written */
uint64_t ub_mmp_magic; /* MMP_MAGIC */
/*
* If ub_mmp_delay == 0 and ub_mmp_magic is valid, MMP is off.
* Otherwise, nanosec since last MMP write.
*/
uint64_t ub_mmp_delay;
/*
* The ub_mmp_config contains the multihost write interval, multihost
* fail intervals, sequence number for sub-second granularity, and
* valid bit mask. This layout is as follows:
*
* 64 56 48 40 32 24 16 8 0
* +-------+-------+-------+-------+-------+-------+-------+-------+
* 0 | Fail Intervals| Seq | Write Interval (ms) | VALID |
* +-------+-------+-------+-------+-------+-------+-------+-------+
*
* This allows a write_interval of (2^24/1000)s, over 4.5 hours
*
* VALID Bits:
* - 0x01 - Write Interval (ms)
* - 0x02 - Sequence number exists
* - 0x04 - Fail Intervals
* - 0xf8 - Reserved
*/
uint64_t ub_mmp_config;
/*
* ub_checkpoint_txg indicates two things about the current uberblock:
*
* 1] If it is not zero then this uberblock is a checkpoint. If it is
* zero, then this uberblock is not a checkpoint.
*
* 2] On checkpointed uberblocks, the value of ub_checkpoint_txg is
* the ub_txg that the uberblock had at the time we moved it to
* the MOS config.
*
* The field is set when we checkpoint the uberblock and continues to
* hold that value even after we've rewound (unlike the ub_txg that
* is reset to a higher value).
*
* Besides checks used to determine whether we are reopening the
* pool from a checkpointed uberblock [see spa_ld_select_uberblock()],
* the value of the field is used to determine which ZIL blocks have
* been allocated according to the ms_sm when we are rewinding to a
* checkpoint. Specifically, if blk_birth > ub_checkpoint_txg, then
* the ZIL block is not allocated [see uses of spa_min_claim_txg()].
*/
uint64_t ub_checkpoint_txg;
uint64_t ub_raidz_reflow_info;
};
#ifdef __cplusplus
}
#endif
#endif /* _SYS_UBERBLOCK_IMPL_H */