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Some settings are not suitable for override in interactive/shell
mode because such settings may confuse the code and it may end
up with unexpected behaviour. This is because of the fact that
once we're in the interactive/shell mode, we have already applied
some settings for the shell itself and we can't override them
further because we're already using those settings to drive the
interactive/shell mode. Such settings would get ignored silently
or, in worse case, they would mess up the existing configuration.
Commit 3928c96a37 introduced
new defaults for raid number of stripes, which may cause
backwards compatibility issues with customer scripts.
Adding configurable option 'raid_stripe_all_devices' defaulting
to '0' (i.e. off = new behaviour) to select the old behaviour
of using all PVs in the VG or those provided on the command line.
In case any scripts rely on the old behaviour, just set
'raid_strip_all_devices = 1'.
- resolves rhbz1354650
New report/output_format configuration sets the output format used
for all LVM commands globally. Currently, there are 2 formats
recognized:
- basic (the classical basic output with columns and rows, used by default)
- json (output is in json format)
Wait to compare and choose alternate duplicate devices until
after all devices are scanned. During scanning, the first
duplicate dev is kept in lvmcache, and others are kept in a
new list (_found_duplicate_devs).
After all devices are scanned, compare all the duplicates
available for a given PVID and decide which is best.
If the dev used in lvmcache is changed, drop the old dev
from lvmcache entirely and rescan the replacement dev.
Previously the VG metadata from the old dev was kept in
lvmcache and only the dev was replaced.
A new config setting devices/allow_changes_with_duplicate_pvs
can be set to 0 which disallows modifying a VG or activating
LVs in it when the VG contains PVs with duplicate devices.
Set to 1 is the old behavior which allowed the VG to be
changed.
The logic for which of two devs is preferred has changed.
The primary goal is to choose a device that is currently
in use if the other isn't, e.g. by an active LV.
. prefer dev with fs mounted if the other doesn't, else
. prefer dev that is dm if the other isn't, else
. prefer dev in subsystem if the other isn't
If neither device is preferred by these rules, then don't
change devices in lvmcache, leaving the one that was found
first.
The previous logic for preferring a device was:
. prefer dev in subsystem if the other isn't, else
. prefer dev without holders if the other has holders, else
. prefer dev that is dm if the other isn't
Move checking the lvmetad state, and the possible rescan,
out of lvmetad_send() to the start of the command.
Previously, the token mismatch and rescan would occur
within lvmetad_send() for some other request. Now,
the token mismatch is detected earlier, so the
rescan can be done before the main command is in
progress. Rescanning deep within the processing of
another command will disturb the lvmcache state of
that other command.
A rescan already exists at the start of the command
for the case where foreign VGs are going to be read.
This same rescan is now also performed when there is
an lvmetad token mismatch (from a changed global_filter).
The commands pvscan/vgscan/lvscan/vgimport are excluded
from this preemptive checking/rescanning for lvmetad
because they want to do rescanning themselves explicitly.
If rescanning devices fails, then lvmetad has not been
correctly repopulated and should not be used, so make
the command revert to not using lvmetad.
When a command modifies a PV or VG, or changes the
activation state of an LV, it will send a dbus
notification when the command is finished. This
can be enabled/disabled with a config setting.
The metadata/record_lvs_history is global switch which enables or
disables recording historical LVs in metadata.
If both metadata/record_lvs_history=1 lvm.conf option and
--nohistory command switch is used at the same time, the
--nohistory prevails.
'verbose' was marked as a boolean option while it
takes integer args - so it has limited usage to 0 or 1,
but we supported 0-4 at least.
Fix it by switching to corrent int type.
(Hopefully noone was trying to use this variable as true/yes/false/no
way - as the would be unsupported/undocumented).
Normally, we generate and provide lvm.conf file where use_blkid_wiping
is set based on whether support for this is compiled in or not. This was
generated properly based on configure.
However, if lvm.conf is not used at all (someone deletes it) or the value
in lvm.conf is commented out (user edited it), we still need to use
proper default value that is based on DEFAULT_USE_BLKID_WIPING taken
from configure script - we used hardcoded value of "1" in this case
by mistake.
The new report/compact_output_cols setting has exactly the same effect
as report/compact_output setting. The difference is that with the new
setting it's possible to define which cols should be compacted exactly
in contrast to all cols in case of report/compact_output.
In case both compact_output and compact_output_cols is enabled/set,
the compact_output prevails.
For example:
$ lvmconfig --type full report/compact_output report/compact_output_cols
compact_output=0
compact_output_cols=""
$ lvs vg
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lvol0 vg -wi-a----- 4.00m
---
$ lvmconfig --type full report/compact_output report/compact_output_cols
compact_output=0
compact_output_cols="data_percent,metadata_percent,pool_lv,move_pv,origin"
$ lvs vg
LV VG Attr LSize Log Cpy%Sync Convert
lvol0 vg -wi-a----- 4.00m
---
$ lvmconfig --type full report/compact_output report/compact_output_cols
compact_output=1
compact_output_cols="data_percent,metadata_percent,pool_lv,move_pv,origin"
$ lvs vg
LV VG Attr LSize
lvol0 vg -wi-a----- 4.00m
This mainly makes the description text use 80 columns.
There are a few minor adjustments to wording to help
the text layout, and a couple minor improvements to
descriptions.
Move code which runtime detects settings for cache_policy
out of config dir to cache seg handling code.
Also mark cache_mode as command profilable setting.
As cache_policy is evaluated in runtime, we no longer should use
CFG_COMMENTED, but have to switch to CFG_UNDEFINED.
So as long as the value is undefined, it's runtime evaluated.
Once it's set - it's always respected (no runtime fallback).
Also fix version of introduced settings to 2.2.128.
Add code to detect available cache features.
Support policy_mq & policy_smq features which might be disabled.
Introduce global_cache_disabled_features_CFG.
Add new profilable configurables:
allocation/cache_policy
allocation/cache_settings
and mark allocation/cache_pool_chunk_size as profilable as well.
Obsolete allocation/cache_pool_cachemode and
introduce new allocation/cache_mode instead.
Rename DEFAULT_CACHE_POOL_POLICY to DEFAULT_CACHE_POLICY.
The CFG_SECTION_NO_CHECK flag can be used to mark a section
and its whole subtree as containing settings where checks
won't be made (lvmconfig --validate).
These are setting where we don't know the names and and type
in advance and they're recognized in runtime. As we don't know
the type and name in advance, we can't do any checks here
of course.
Use this flag with great care as it disables config checks
for the whole config subtree found under such section.
This flag is going to be used by subsequent patches from
Zdenek to support some cache settings...
Require global/{thin,cache}_{check,repair}_options to be always defined.
If not defined directly by user in the configuration and if there's no
concrete default option to use, make "" (empty string) the default one -
it's then clearly visible in the "lvmconfig --type default" (and
generated lvm.conf) and also it makes its handling in the code more
straightforward so we don't need to handle undefined values.
This means, if there are no default values for these settings defined,
we end up with this generated now:
{thin,cache}_{check,repair}_options = [ "" ]
So the value is never undefined and if it is, it's an error.
(The cache_repair_options is actually not used in the code at the moment,
but once the code using this setting is in, it will follow the same logic
as used for thin_repair_options.)
including the allow_override_lock_modes setting.
It was not possible to override default lock modes any longer,
since the command line options had already been removed.
A mechanism will probably be required later that puts part of
this back.
Just like we have DEFAULT_USE_LVMETAD (or DEFUALT_USE_LVMPOLLD), use
fallback_to_lvm1=1 lvm.conf setting if we configured lvm2 with
--enable-lvm1-fallback and use fallback_to_lvm1=0 otherwise.
Also, generate proper lvm.conf.in with unconfigured value.
Make it possible to define format for time that is displayed.
The way the format is defined is equal to the way that is used
for strftime function, although not all formatting options as
used in strftime are available for LVM2 - the set is restricted
(e.g. we do not allow newline to be printed). The lvm.conf
comments contain the whole list that LVM2 accepts for time format
together with brief description (copied from strftime man page).
For example:
(defaults used - the format is the same as used before this patch)
$ lvs -o+time vg/lvol0 vg/lvol1
LV VG Attr LSize Time
lvol0 vg -wi-a----- 4.00m 2015-06-25 16:18:34 +0200
lvol1 vg -wi-a----- 4.00m 2015-06-29 09:17:11 +0200
(using 'time_format = "@%s"' in lvm.conf - number of seconds
since the Epoch)
$ lvs -o+time vg/lvol0 vg/lvol1
LV VG Attr LSize Time
lvol0 vg -wi-a----- 4.00m @1435241914
lvol1 vg -wi-a----- 4.00m @1435562231
It's not an error to define empty values for
{thin,cache}_{check,repair}_options - such empty value means no
options are passed when these external commands are called.
If blkid wiping is possible, than set use_blkid_wiping=1 and
use_blkid_wiping=0 otherwise for its default value. If blkid wiping
is disabled during configure and use_blkid_wiping=1 is set by chance,
it's simply ignored - this patch is just a cleanup that makes it more
obvious for the user (we use similar logic for use_lvmetad and
use_lvmpolld settings).
Default value for lvmetad and lvmpolld has hooks in configure script,
the "lvmconfig --type default --unconfigured" should display:
use_lvmetad = @DEFAULT_USE_LVMETAD@
use_lvmpolld = @DEFAULT_USE_LVMPOLLD@
Note that these settings are not of string type. Recent change (the
DM_CONFIG_VALUE_FMT_STRING_NO_QUOTES formatting flag) makes it
possible to recognize that the setting is not of string type and if
there's unconfigured value defined for it, the enclosing " " is
automatically removed on output.
Do not use "#S" (blank string) as default value as that ends up with
'key = [ "" ]' to be generated which is not what we want in most cases.
Also, fix default values for global/{thin,cache}_{check,repair}_options
and avoid assigning blank values. For example, the thin_check_options
had this set as default value previously:
"#S" DEFAULT_THIN_CHECK_OPTION1 "#S" DEFAULT_THIN_CHECK_OPTION2
If any (or both) of DEFAULT_THIN_CHECK_OPTION* variables was set
to "", we ended up with clumsy default value generated like:
thin_check_options = [ "-q", "" ]
With this patch, we end up with correct:
thin_check_options = [ "-q" ]
or, if all options are undefined:
thin_check_options = [ ]
Which is the correct way to express this.
There are two basic groups of formatting flags (32 bits):
- common ones applicable for all config value types (lower 16 bits)
- type-related formatting flags (higher 16 bits)
With this patch, we initially support four new flags that
modify the the way the config value is displayed:
Common flags:
=============
DM_CONFIG_VALUE_FMT_COMMON_ARRAY - causes array config values
to be enclosed in "[ ]" even if there's only one item
(previously, there was no way to recognize an array with one
item and scalar value, hence array values with one member
were always displayed without "[ ]" which libdm accepted
when reading, but it may have been misleading for users)
DM_CONFIG_VALUE_FMT_COMMON_EXTRA_SPACE - causes extra spaces to
be inserted in "key = value" (or key = [ value, value, ... ] in
case of arrays), compared to "key=value" seen on output before.
This makes the output more readable for users.
Type-related flags:
===================
DM_CONFIG_VALUE_FMT_INT_OCTAL - prints integers in octal form with
"0" as a prefix (libdm's config reading code can handle this via
strtol just fine so it's properly recognized as number in octal
form already if there's "0" used as prefix)
DM_CONFIG_VALUE_FMT_STRING_NO_QUOTES - makes it possible to print
strings without enclosing " "
This patch also adds dm_config_value_set_format_flags and
dm_config_value_get_format_flags functions to set and get
these formatting flags.
This patch fixes segfault which was caused by incorrectly marking some
settings CFG_DEFAULT_COMMENTED instead of CFG_DEFAULT_UNDEFINED - the
ones which have NULL default value, hence they're really undefined.
A regression caused by a98ceceb1d.
For example:
$ lvmconfig log/file
file="/a"
Before this patch:
$ lvmconfig --type diff
Segmentation fault (core dumped)
With this patch applied:
$ lvmconfig --type diff
log {
file="/a"
}
The same applies for these settings:
log/activate_file
global/library_dir
global/system_id_file
<disk_area>/disk_area_id
There were also other settings with NULL default value and marked as
CFG_DEFAULT_COMMENTED instead of CFG_DEFAULT_UNDEFINED, but they were
cfg_array config settings where the NULL value was not causing segfault
(NULL == empty array).
Use CFG_DEFAULT_COMMENTED and CFG_DEFAULT_UNDEFINED to
replicate the existing comments in example.conf.
Fix host_list to be cfg_array.
UNDEFINED is only used if the value depends on other
system/kernel values outside of lvm. The most common
case is when dm-thin or dm-cache have built-in default
settings in the kernel, and lvm will use those built-in
default values unless the corresponding lvm config setting
is set.
COMMENTED is used to comment out the default setting in
lvm.conf. The effect is that if the LVM version is
upgraded, and the new version of LVM has new built-in
default values, the new defaults are used by LVM unless
the previous default value was set (uncommented) in lvm.conf.
Configure provides proper settings for
use_lvmetad and use_lvmpolld conf setttings.
When the build of polld & lvmetad, these settings
are enabled by default unless explicitelly disabled
with --disable-use-lvmetad/--disable-use-lvmpolld.
A preparatory code for marking configuration nodes as deprecated:
- struct cfg_def_item gains 2 new fields ("deprecated_since_version" and "deprecation_comment"
- cfg* macros to handle new fields
- related config_settings.h edits to add new fields for each item (null for all at the moment)
Patch with implementation will follow...
These settings are in the "unsupported" group:
devices/loopfiles
log/activate_file
metadata/disk_areas (section)
metadata/disk_areas/<disk_area> (section)
metadata/disk_areas/<disk_area>/size
metadata/disk_areas/<disk_area>/id
These settings are in the "advanced" group:
devices/dir
devices/scan
devices/types
global/proc
activation/missing_stripe_filler
activation/mlock_filter
metadata/pvmetadatacopies
metadata/pvmetadataignore
metadata/stripesize
metadata/dirs
Also, this patch causes the --ignoreunsupported and --ignoreadvanced
switches to be honoured for all config types (lvmconfig --type).
By default, the --type current and --type diff display unsupported
settings, the other types ignore them - this patch also introduces
--showunsupported switch for all these other types to display even
unsupported settings in their output if needed.
Describe
thin_check_options, thin_repair_options,
cache_check_option, scache_repair_options
as a "list of options", rather than a "string of options"
because a single string, e.g. "-q --clear-needs-check-flag"
does not work, and needs to be entered as a list,
e.g. ["-q", "--clear-needs-check-flag"]
The settings which have their default value evaluated in runtime should
have their 'unconfigured' counterparts also evaluated in runtime since
those values can be constructed by using other settings.
For example, before this patch:
$ lvm dumpconfig --type default --unconfigured devices/cache_dir devices/cache
cache_dir="@DEFAULT_SYS_DIR@/@DEFAULT_CACHE_SUBDIR@"
cache="/etc/lvm/cache/.cache
With this patch applied:
$ lvm dumpconfig --type default --unconfigured devices/cache_dir devices/cache
cache_dir="@DEFAULT_SYS_DIR@/@DEFAULT_CACHE_SUBDIR@"
cache="@DEFAULT_SYS_DIR@/@DEFAULT_CACHE_SUBDIR@/.cache"
By default these are empty strings, so the config settings
should be flagged as undefined, so they will be commented
out of the generated config. Otherwise, the lines:
thin_repair_options=""
cache_repair_options=""
in the dump output cause a warning when processed since
lvm doesn't want an empty string.
Also regenerate lvm.conf.in.
Comments from the sample config files are copied into
the comment field of the config settings structure.
This includes only minimal changes to the text.
With this in place, the sample config files can
be generated from 'lvm dumpconfig', and content
for an lvm.conf man page can also be generated.
If configuration setting is marked in config_setting.h with CFG_DISABLED
flag, default value is always used for such setting, no matter if it's defined
by user (in --config/lvm.conf/lvmlocal.conf).
A warning message is displayed if this happens:
For example:
[1] f21/~ # lvm dumpconfig --validate
WARNING: Configuration setting global/system_id_source is disabled. Using default value.
LVM configuration valid.
[1] f21/~ # pvs
WARNING: Configuration setting global/system_id_source is disabled. Using default value.
PV VG Fmt Attr PSize PFree
/dev/sdb lvm2 --- 128.00m 128.00m
...
Allow cmd->unknown_system_id to be cleared during toolcontext
refresh.
Set a default value of "none" for global/system_id_source.
Allow local/system_id to be empty so it's not impossible for
a later config file to remove it.
Just like MD filtering that detects components of software RAID (md),
add detection for firmware RAID.
We're not adding any native code to detect this - there are lots of
firmware RAIDs out there which is just out of LVM scope. However,
with current changes with which we're able to get device info from
external sources (e.g. external_device_info_source="udev"), we can
do this easily if the external device status source has this kind
of information - which is the case of "udev" source where the results
of blkid scans are stored.
This detection should cover all firmware RAIDs that blkid can detect and
which are identified as:
ID_FS_TYPE = {adaptec,ddf,hpt45x,hpt37x,isw,jmicron,lsi_mega,nvidia,promise_fasttrack,silicon_medley,via}_raid_member
Support error_if_no_space feature for thin pools.
Report more info about thinpool status:
(out_of_data (D), metadata_read_only (M), failed (F) also as health
attribute.)
Support compile type configurable defaults for creation
of sparse volumes.
By default now create 'thin-pools' for sparse volumes.
Use the global/sparse_segtype_default to switch back to old
snapshots if needed.
Apply the same compile logic for newly introduces mirror/raid1 options.
The cache mode of a new cache pool is always explicitly
included in the vg metadata. If a cache mode is not
specified on the command line, the cache mode is taken
from lvm.conf allocation/cache_pool_cachemode, which
defaults to "writethrough".
The cache mode can be displayed with lvs -o+cachemode.
Currently, we have two modes of activation, an unnamed nominal mode
(which I will refer to as "complete") and "partial" mode. The
"complete" mode requires that a volume group be 'complete' - that
is, no missing PVs. If there are any missing PVs, no affected LVs
are allowed to activate - even RAID LVs which might be able to
tolerate a failure. The "partial" mode allows anything to be
activated (or at least attempted). If a non-redundant LV is
missing a portion of its addressable space due to a device failure,
it will be replaced with an error target. RAID LVs will either
activate or fail to activate depending on how badly their
redundancy is compromised.
This patch adds a third option, "degraded" mode. This mode can
be selected via the '--activationmode {complete|degraded|partial}'
option to lvchange/vgchange. It can also be set in lvm.conf.
The "degraded" activation mode allows RAID LVs with a sufficient
level of redundancy to activate (e.g. a RAID5 LV with one device
failure, a RAID6 with two device failures, or RAID1 with n-1
failures). RAID LVs with too many device failures are not allowed
to activate - nor are any non-redundant LVs that may have been
affected. This patch also makes the "degraded" mode the default
activation mode.
The degraded activation mode does not yet work in a cluster. A
new cluster lock flag (LCK_DEGRADED_MODE) will need to be created
to make that work. Currently, there is limited space for this
extra flag and I am looking for possible solutions. One possible
solution is to usurp LCK_CONVERT, as it is not used. When the
locking_type is 3, the degraded mode flag simply gets dropped and
the old ("complete") behavior is exhibited.
The --binary option, if used, causes all the binary values reported
in reporting commands to be displayed as "0" or "1" instead of descriptive
literal values (value "unknown" is still used for values that could not be
determined).
Also, add report/binary_values_as_numeric lvm.conf option with the same
functionality as the --binary option (the --binary option prevails
if both --binary cmd option and report/binary_values_as_numeric lvm.conf
option is used at the same time). The report/binary_values_as_numeric is
also profilable.
This makes it easier to use and check lvm reporting command output in scripts.
Mark profilable settings with a separate CFG_PROFILABLE_METADATA
flag where the profile can be attached to VG/LV. This makes it possible
to differentiate global command-profilable settings (CFG_PROFILABLE flag)
and contextual metadata-profilable (per VG/LV) settings (CFG_PROFILABLE_METADATA flag).
Before:
thin_disabled_features = ""
Now:
thin_disabled_features = []
Which is a more correct and consistent way of specifying void array
though parses can handle both forms.
The global/suffix was missing from example lvm.conf but it can
be very useful when using lvm in scripts and now in profiles as well
Let's expose it more.
Users can create several profiles for how the tools report
the output very easily and then just use
<lvm reporting command> --profile <report_profile_name>
Let's do this the other way round - this makes more logic than commit b995f06.
So let's allow empty values for global/thin_disabled_features where
such an empty value now means "none of this features are disabled".
The global/thin_disabled_features should be marked as having no default
value. Otherwise the output from 'lvm dumpconfig --type default' would
have 'thin_disabled_features=""' which will produce an error message
'Ignoring empty string in config file ...' if such output is feed
back to lvm.
The same as for allocation/thin_pool_chunk_size - the default value
used is just a starting point. The calculation continues using the
properties of the devices actually used.
The allocation/thin_pool_chunk_size is a bit more complex. It's default
value is evaluated in runtime based on selected thin_pool_chunk_size_policy.
But the value is just a starting point. The calculation then continues
with dependency on the properties of the devices used. Which means for
such a default value, we know only the starting value.
The devices/cache and devices/cache_dir are evaluated in runtime this way:
- if devices/cache is set, use it
- if devices_cache/dir or devices/cache_file_prefix is set, make up a
path out of that for devices/cache in runtime, taking into account
the LVM_SYSTEM_DIR environment variable if set
- otherwise make up the path out of default which is:
<LVM_SYSTEM_DIR>/<cache_dir>/<cache_file_prefix>.cache
With the runtime defaults, we can encode this easily now. Also, the lvm
dumpconfig can show proper and exact information about this setting then
(the variant that shows default values).
Previously, we declared a default value as undefined ("NULL") for
settings which require runtime context to be set first (e.g. settings
for paths that rely on SYSTEM_DIR environment variable or they depend
on any other setting in some way).
If we want to output default values as they are really used in runtime,
we should make it possible to define a default value as function which
is evaluated, not just providing a firm constant value as it was before.
This patch defines simple prototypes for such functions. Also, there's
new helper macros "cfg_runtime" and "cfg_array_runtime" - they provide
exactly the same functionality as the original "cfg" and "cfg_array"
macros when defining the configuration settings in config_settings.h,
but they don't set the constant default value. Instead, they automatically
link the configuration setting definition with one of these functions:
typedef int (*t_fn_CFG_TYPE_BOOL) (struct cmd_context *cmd, struct profile *profile);
typedef int (*t_fn_CFG_TYPE_INT) (struct cmd_context *cmd, struct profile *profile);
typedef float (*t_fn_CFG_TYPE_FLOAT) (struct cmd_context *cmd, struct profile *profile);
typedef const char* (*t_fn_CFG_TYPE_STRING) (struct cmd_context *cmd, struct profile *profile);
typedef const char* (*t_fn_CFG_TYPE_ARRAY) (struct cmd_context *cmd, struct profile *profile);
(The new macros actually set the CFG_DEFAULT_RUNTIME flag properly and
set the default value link to the function accordingly).
Then such configuration setting requires a function of selected type to
be defined. This function has a predefined name:
get_default_<id>
...where the <id> is the id of the setting as defined in
config_settings.h. For example "backup_archive_dir_CFG" if defined
as a setting with default value evaluated in runtime with "cfg_runtime"
will automatically have "get_default_backup_archive_dir_CFG" function
linked to this setting to get the default value.
These settings don't have any default value predefined:
log/file
log/activate_file
global/library_dir
This settings has default value but not yet declared in config_settings.h:
global/locking_library (default is DEFAULT_LOCKING_LIB)
To make "lvm dumpconfig --type default" output to be usable like any
other config, we need to comment out lines that have no default value
defined. Otherwise, we'd have the output with config options
with blank or zero values which is not the same as when the value
is not defined! And such configuration can't be feed into lvm again
without further edits. So let's fix this.
Currently this covers these configuration options exactly:
devices/loopfiles
devices/preferred_names
devices/filter
devices/global_filter
devices/types
allocation/cling_tag_list
global/format_libraries
global/segment_libraries
activation/volume_list
activation/auto_activation_volume_list
activation/read_only_volume_list
activation/mlock_filter
metadata/dirs
metadata/disk_areas
metadata/disk_areas/<disk_area>
metadata/disk_areas/<disk_area>/start_sector
metadata/disk_areas/<disk_area>/size
metadata/disk_areas/<disk_area>/id
tags/<tag>
tags/<tag>/host_list
Cache pools require a data and metadata area (like thin pools). Unlike
thin pool, if 'cache_pool_metadata_require_separate_pvs' is not set to
'1', the metadata and data area will be allocated from the same device.
It is also done in a manner similar to RAID, where a single chunk of
space is allocated and then split to form the metadata and data device -
ensuring that they are together.
The metadata/disk_areas setting was incorrectly registered as
"string" configuration option but it's a section where each area
is defined in its own subsection with "start_sector", "size" and "id"
setting.
This setting is not officialy supported, it's undocumented and it's
used solely for debugging.
Note: At this moment, it does not seem to be working with lvmetad!
There is a problem with the way mirrors have been designed to handle
failures that is resulting in stuck LVM processes and hung I/O. When
mirrors encounter a write failure, they block I/O and notify userspace
to reconfigure the mirror to remove failed devices. This process is
open to a couple races:
1) Any LVM process other than the one that is meant to deal with the
mirror failure can attempt to read the mirror, fail, and block other
LVM commands (including the repair command) from proceeding due to
holding a lock on the volume group.
2) If there are multiple mirrors that suffer a failure in the same
volume group, a repair can block while attempting to read the LVM
label from one mirror while trying to repair the other.
Mitigation of these races has been attempted by disallowing label reading
of mirrors that are either suspended or are indicated as blocking by
the kernel. While this has closed the window of opportunity for hitting
the above problems considerably, it hasn't closed it completely. This is
because it is still possible to start an LVM command, read the status of
the mirror as healthy, and then perform the read for the label at the
moment after a the failure is discovered by the kernel.
I can see two solutions to this problem:
1) Allow users to configure whether mirrors can be candidates for LVM
labels (i.e. whether PVs can be created on mirror LVs). If the user
chooses to allow label scanning of mirror LVs, it will be at the expense
of a possible hang in I/O or LVM processes.
2) Instrument a way to allow asynchronous label reading - allowing
blocked label reads to be ignored while continuing to process the LVM
command. This would action would allow LVM commands to continue even
though they would have otherwise blocked trying to read a mirror. They
can then release their lock and allow a repair command to commence. In
the event of #2 above, the repair command already in progress can continue
and repair the failed mirror.
This patch brings solution #1. If solution #2 is developed later on, the
configuration option created in #1 can be negated - allowing mirrors to
be scanned for labels by default once again.
Add allocation/thin_pool_chunk_size_calculation lvm.conf
option to select a method for calculating thin pool chunk
sizes and define two possible values - "default" and "performance".
Add internal devtypes reporting command to display built-in recognised
block device types. (The output does not include any additional
types added by a configuration file.)
> lvm devtypes -o help
Device Types Fields
-------------------
devtype_all - All fields in this section.
devtype_name - Name of Device Type exactly as it appears in /proc/devices.
devtype_max_partitions - Maximum number of partitions. (How many device minor numbers get reserved for each device.)
devtype_description - Description of Device Type.
> lvm devtypes
DevType MaxParts Description
aoe 16 ATA over Ethernet
ataraid 16 ATA Raid
bcache 1 bcache block device cache
blkext 1 Extended device partitions
...
Add new configure lvm.conf options for binaries thin_repair
and thin_dump.
Those are part of device-mapper-persistent-data package
and will be used for recovery of thin_pool.
