mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-01 09:26:44 +07:00
c4a3955145
MD: Remember the last sync operation that was performed This patch adds a field to the mddev structure to track the last sync operation that was performed. This is especially useful when it comes to what is recorded in mismatch_cnt in sysfs. If the last operation was "data-check", then it reports the number of descrepancies found by the user-initiated check. If it was a "repair" operation, then it is reporting the number of descrepancies repaired. etc. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: NeilBrown <neilb@suse.de>
227 lines
9.5 KiB
Plaintext
227 lines
9.5 KiB
Plaintext
dm-raid
|
|
=======
|
|
|
|
The device-mapper RAID (dm-raid) target provides a bridge from DM to MD.
|
|
It allows the MD RAID drivers to be accessed using a device-mapper
|
|
interface.
|
|
|
|
|
|
Mapping Table Interface
|
|
-----------------------
|
|
The target is named "raid" and it accepts the following parameters:
|
|
|
|
<raid_type> <#raid_params> <raid_params> \
|
|
<#raid_devs> <metadata_dev0> <dev0> [.. <metadata_devN> <devN>]
|
|
|
|
<raid_type>:
|
|
raid1 RAID1 mirroring
|
|
raid4 RAID4 dedicated parity disk
|
|
raid5_la RAID5 left asymmetric
|
|
- rotating parity 0 with data continuation
|
|
raid5_ra RAID5 right asymmetric
|
|
- rotating parity N with data continuation
|
|
raid5_ls RAID5 left symmetric
|
|
- rotating parity 0 with data restart
|
|
raid5_rs RAID5 right symmetric
|
|
- rotating parity N with data restart
|
|
raid6_zr RAID6 zero restart
|
|
- rotating parity zero (left-to-right) with data restart
|
|
raid6_nr RAID6 N restart
|
|
- rotating parity N (right-to-left) with data restart
|
|
raid6_nc RAID6 N continue
|
|
- rotating parity N (right-to-left) with data continuation
|
|
raid10 Various RAID10 inspired algorithms chosen by additional params
|
|
- RAID10: Striped Mirrors (aka 'Striping on top of mirrors')
|
|
- RAID1E: Integrated Adjacent Stripe Mirroring
|
|
- RAID1E: Integrated Offset Stripe Mirroring
|
|
- and other similar RAID10 variants
|
|
|
|
Reference: Chapter 4 of
|
|
http://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf
|
|
|
|
<#raid_params>: The number of parameters that follow.
|
|
|
|
<raid_params> consists of
|
|
Mandatory parameters:
|
|
<chunk_size>: Chunk size in sectors. This parameter is often known as
|
|
"stripe size". It is the only mandatory parameter and
|
|
is placed first.
|
|
|
|
followed by optional parameters (in any order):
|
|
[sync|nosync] Force or prevent RAID initialization.
|
|
|
|
[rebuild <idx>] Rebuild drive number 'idx' (first drive is 0).
|
|
|
|
[daemon_sleep <ms>]
|
|
Interval between runs of the bitmap daemon that
|
|
clear bits. A longer interval means less bitmap I/O but
|
|
resyncing after a failure is likely to take longer.
|
|
|
|
[min_recovery_rate <kB/sec/disk>] Throttle RAID initialization
|
|
[max_recovery_rate <kB/sec/disk>] Throttle RAID initialization
|
|
[write_mostly <idx>] Mark drive index 'idx' write-mostly.
|
|
[max_write_behind <sectors>] See '--write-behind=' (man mdadm)
|
|
[stripe_cache <sectors>] Stripe cache size (RAID 4/5/6 only)
|
|
[region_size <sectors>]
|
|
The region_size multiplied by the number of regions is the
|
|
logical size of the array. The bitmap records the device
|
|
synchronisation state for each region.
|
|
|
|
[raid10_copies <# copies>]
|
|
[raid10_format <near|far|offset>]
|
|
These two options are used to alter the default layout of
|
|
a RAID10 configuration. The number of copies is can be
|
|
specified, but the default is 2. There are also three
|
|
variations to how the copies are laid down - the default
|
|
is "near". Near copies are what most people think of with
|
|
respect to mirroring. If these options are left unspecified,
|
|
or 'raid10_copies 2' and/or 'raid10_format near' are given,
|
|
then the layouts for 2, 3 and 4 devices are:
|
|
2 drives 3 drives 4 drives
|
|
-------- ---------- --------------
|
|
A1 A1 A1 A1 A2 A1 A1 A2 A2
|
|
A2 A2 A2 A3 A3 A3 A3 A4 A4
|
|
A3 A3 A4 A4 A5 A5 A5 A6 A6
|
|
A4 A4 A5 A6 A6 A7 A7 A8 A8
|
|
.. .. .. .. .. .. .. .. ..
|
|
The 2-device layout is equivalent 2-way RAID1. The 4-device
|
|
layout is what a traditional RAID10 would look like. The
|
|
3-device layout is what might be called a 'RAID1E - Integrated
|
|
Adjacent Stripe Mirroring'.
|
|
|
|
If 'raid10_copies 2' and 'raid10_format far', then the layouts
|
|
for 2, 3 and 4 devices are:
|
|
2 drives 3 drives 4 drives
|
|
-------- -------------- --------------------
|
|
A1 A2 A1 A2 A3 A1 A2 A3 A4
|
|
A3 A4 A4 A5 A6 A5 A6 A7 A8
|
|
A5 A6 A7 A8 A9 A9 A10 A11 A12
|
|
.. .. .. .. .. .. .. .. ..
|
|
A2 A1 A3 A1 A2 A2 A1 A4 A3
|
|
A4 A3 A6 A4 A5 A6 A5 A8 A7
|
|
A6 A5 A9 A7 A8 A10 A9 A12 A11
|
|
.. .. .. .. .. .. .. .. ..
|
|
|
|
If 'raid10_copies 2' and 'raid10_format offset', then the
|
|
layouts for 2, 3 and 4 devices are:
|
|
2 drives 3 drives 4 drives
|
|
-------- ------------ -----------------
|
|
A1 A2 A1 A2 A3 A1 A2 A3 A4
|
|
A2 A1 A3 A1 A2 A2 A1 A4 A3
|
|
A3 A4 A4 A5 A6 A5 A6 A7 A8
|
|
A4 A3 A6 A4 A5 A6 A5 A8 A7
|
|
A5 A6 A7 A8 A9 A9 A10 A11 A12
|
|
A6 A5 A9 A7 A8 A10 A9 A12 A11
|
|
.. .. .. .. .. .. .. .. ..
|
|
Here we see layouts closely akin to 'RAID1E - Integrated
|
|
Offset Stripe Mirroring'.
|
|
|
|
<#raid_devs>: The number of devices composing the array.
|
|
Each device consists of two entries. The first is the device
|
|
containing the metadata (if any); the second is the one containing the
|
|
data.
|
|
|
|
If a drive has failed or is missing at creation time, a '-' can be
|
|
given for both the metadata and data drives for a given position.
|
|
|
|
|
|
Example Tables
|
|
--------------
|
|
# RAID4 - 4 data drives, 1 parity (no metadata devices)
|
|
# No metadata devices specified to hold superblock/bitmap info
|
|
# Chunk size of 1MiB
|
|
# (Lines separated for easy reading)
|
|
|
|
0 1960893648 raid \
|
|
raid4 1 2048 \
|
|
5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81
|
|
|
|
# RAID4 - 4 data drives, 1 parity (with metadata devices)
|
|
# Chunk size of 1MiB, force RAID initialization,
|
|
# min recovery rate at 20 kiB/sec/disk
|
|
|
|
0 1960893648 raid \
|
|
raid4 4 2048 sync min_recovery_rate 20 \
|
|
5 8:17 8:18 8:33 8:34 8:49 8:50 8:65 8:66 8:81 8:82
|
|
|
|
|
|
Status Output
|
|
-------------
|
|
'dmsetup table' displays the table used to construct the mapping.
|
|
The optional parameters are always printed in the order listed
|
|
above with "sync" or "nosync" always output ahead of the other
|
|
arguments, regardless of the order used when originally loading the table.
|
|
Arguments that can be repeated are ordered by value.
|
|
|
|
|
|
'dmsetup status' yields information on the state and health of the array.
|
|
The output is as follows (normally a single line, but expanded here for
|
|
clarity):
|
|
1: <s> <l> raid \
|
|
2: <raid_type> <#devices> <health_chars> \
|
|
3: <sync_ratio> <sync_action> <mismatch_cnt>
|
|
|
|
Line 1 is the standard output produced by device-mapper.
|
|
Line 2 & 3 are produced by the raid target and are best explained by example:
|
|
0 1960893648 raid raid4 5 AAAAA 2/490221568 init 0
|
|
Here we can see the RAID type is raid4, there are 5 devices - all of
|
|
which are 'A'live, and the array is 2/490221568 complete with its initial
|
|
recovery. Here is a fuller description of the individual fields:
|
|
<raid_type> Same as the <raid_type> used to create the array.
|
|
<health_chars> One char for each device, indicating: 'A' = alive and
|
|
in-sync, 'a' = alive but not in-sync, 'D' = dead/failed.
|
|
<sync_ratio> The ratio indicating how much of the array has undergone
|
|
the process described by 'sync_action'. If the
|
|
'sync_action' is "check" or "repair", then the process
|
|
of "resync" or "recover" can be considered complete.
|
|
<sync_action> One of the following possible states:
|
|
idle - No synchronization action is being performed.
|
|
frozen - The current action has been halted.
|
|
resync - Array is undergoing its initial synchronization
|
|
or is resynchronizing after an unclean shutdown
|
|
(possibly aided by a bitmap).
|
|
recover - A device in the array is being rebuilt or
|
|
replaced.
|
|
check - A user-initiated full check of the array is
|
|
being performed. All blocks are read and
|
|
checked for consistency. The number of
|
|
discrepancies found are recorded in
|
|
<mismatch_cnt>. No changes are made to the
|
|
array by this action.
|
|
repair - The same as "check", but discrepancies are
|
|
corrected.
|
|
reshape - The array is undergoing a reshape.
|
|
<mismatch_cnt> The number of discrepancies found between mirror copies
|
|
in RAID1/10 or wrong parity values found in RAID4/5/6.
|
|
This value is valid only after a "check" of the array
|
|
is performed. A healthy array has a 'mismatch_cnt' of 0.
|
|
|
|
Message Interface
|
|
-----------------
|
|
The dm-raid target will accept certain actions through the 'message' interface.
|
|
('man dmsetup' for more information on the message interface.) These actions
|
|
include:
|
|
"idle" - Halt the current sync action.
|
|
"frozen" - Freeze the current sync action.
|
|
"resync" - Initiate/continue a resync.
|
|
"recover"- Initiate/continue a recover process.
|
|
"check" - Initiate a check (i.e. a "scrub") of the array.
|
|
"repair" - Initiate a repair of the array.
|
|
"reshape"- Currently unsupported (-EINVAL).
|
|
|
|
Version History
|
|
---------------
|
|
1.0.0 Initial version. Support for RAID 4/5/6
|
|
1.1.0 Added support for RAID 1
|
|
1.2.0 Handle creation of arrays that contain failed devices.
|
|
1.3.0 Added support for RAID 10
|
|
1.3.1 Allow device replacement/rebuild for RAID 10
|
|
1.3.2 Fix/improve redundancy checking for RAID10
|
|
1.4.0 Non-functional change. Removes arg from mapping function.
|
|
1.4.1 RAID10 fix redundancy validation checks (commit 55ebbb5).
|
|
1.4.2 Add RAID10 "far" and "offset" algorithm support.
|
|
1.5.0 Add message interface to allow manipulation of the sync_action.
|
|
New status (STATUSTYPE_INFO) fields: sync_action and mismatch_cnt.
|
|
1.5.1 Add ability to restore transiently failed devices on resume.
|
|
1.5.2 'mismatch_cnt' is zero unless [last_]sync_action is "check".
|