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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.
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.
Some code has been added recently which makes it impossible to compile
when "configure --disable-devmapper" is used. This patch just shuffles
the code around so it's under proper #ifdef DEVMAPPER_SUPPORT.
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
...
When both the '-i' and '-m' arguments are specified on the command
line, use the "raid10" segment type. This way, the native RAID10
personality is used through dm-raid rather than layering a mirror
on striped LVs. If the old behavior is desired, the '--type'
argument to use would be "mirror" rather than "raid10".
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.
Add --poolmetadataspare option and creates and handles
pool metadata spare lv when thin pool is created.
With default setting 'y' it tries to ensure, spare has
at least the size of created LV.
The activation/auto_set_activation_skip enables/disables automatic
adding of the ACTIVATION_SKIP LV flag. By default thin snapshots
are flagged to be skipped during activation.
And by default, the auto_set_activation_skip is enabled.
For example, the old call and reference:
find_config_tree_str(cmd, "devices/dir", DEFAULT_DEV_DIR)
...now becomes:
find_config_tree_str(cmd, devices_dir_CFG)
So we're referring to the named configuration ID instead
of passing the configuration path and the default value
is taken from central config definition in config_settings.h
automatically.
If '--mirrors/-m' and '--stripes/-i' are used together when creating
a logical volume, mirrors-over-stripes is currently chosen. The user
can override this by using the '--type raid10' option on creation.
However, we want a place where we can set the default behavior to
'raid10' explicitly - similar to the "mirror" and "raid1" tunable,
mirror_segtype_default.
A follow-on patch should use this new setting to change the default
from "mirror" to "raid10", as this is the preferred segment type.
We have been using 'mirror_region_size' in lvm.conf as the default region
size for RAID logical volumes as well as mirror logical volumes. Since,
"raid" is more inclusive and representative than "mirror", I have changed
the name of this setting. We must still check for the old setting and warn
the user if we are overriding it with the new setting if both happen to be
present.
Add log/debug_classes to lvm.conf to allow debug messages to be
classified and filtered at runtime.
The dm_errno field is only used by log_error(), so I've redefined it
for log_debug() messages to hold the message class.
By default, all existing messages appear, but we can add categories that
generate high volumes of data, such as logging all traffic to/from
lvmetad.
Configurable settings for thin pool create
if they are not specified on command line.
New supported lvm.conf options are:
allocation/thin_pool_chunk_size
allocation/thin_pool_discards
allocation/thin_pool_zero
Accept -q as the short form of --quiet.
Suppress non-essential standard output if -q is given twice.
Treat log/silent in lvm.conf as equivalent to -qq.
Review all log_print messages and change some to
log_print_unless_silent.
When silent, the following commands still produce output:
dumpconfig, lvdisplay, lvmdiskscan, lvs, pvck, pvdisplay,
pvs, version, vgcfgrestore -l, vgdisplay, vgs.
[Needs checking.]
Non-essential messages are shifted from log level 4 to log level 5
for syslog and lvm2_log_fn purposes.
Update a way we handle option passing - so we now support path and options
with space inside.
Fix dm name usage for thin pools with '-' in name.
Use new lvm.conf option thin_check_options to pass in options as string array.
If the lvcreate may decide some automagical values for a user,
try to keep the pool metadata size into 128MB range for optimal
perfomance (as suggested by Joe).
So if the pool metadata size and chunk_size were not specified,
try to select such values they would fit into 128MB size.
Use libdm callback to execute thin_check before activation
thin pool and after deactivation as well.
Supporting thin_check_executable which may pass in extra options for
the tool.
Reformat name and path how the LV is represented with lvm1 compatible option,
to switch to the old way - which had number of problem - i.e. many links
do not exist - since for private devices we are not creating them.
Add more info about thin pools and volumes.
New field Data% is able to display info about
thin_pool, thin, snapshot and has generic meaning here.
Simple Time/Host field are here to display host and time creation.
The RAID plug-in for dmeventd now calls 'lvconvert --repair' to address failures
of devices in a RAID logical volume. The action taken can be either to "warn"
or "allocate" a new device from any spares that may be available in the
volume group. The action is designated by setting 'raid_fault_policy' in
lvm.conf - the default being "warn".
LVM metadata knows only of striped segments - not linear ones.
The activation code detects segments with a single stripe and switches
them to use the linear target.
If the new lvm.conf setting is set to 0 (e.g. in a test script), this
'optimisation' is turned off.
Add filter which tries to check if scanned device is part
of active multipath.
Firstly, only SCSI major number devices are handled in filter.
Then it checks if device has exactly one holder (in sysfs) and
if it is device-mapper device and DM-UUID is prefixed by "MPATH-".
If so, this device is filtered out.
The whole filter can be switched off by setting
mpath_component_detection in lvm.conf.
https://bugzilla.redhat.com/show_bug.cgi?id=597010
Signed-off-by: Milan Broz <mbroz@redhat.com>
Go with just 64KiB for stack.
Closer inspection should be made, whether we actually need to play with
settings at all.
Since default stack size is 8MB and gets mapped via page locking thus,
it seems there is no big help with preallocation of stack to some value.
A gentle reminder that anyone relying on the output of reporting commands
like lvs in scripts must use -o to guarantee they get the fields they expect.
The default sequence of fields can change from release to release.
Equally, the 'attr' fields can have new values introduced and/or characters
appended to them.
Add config option to enable crc checking of VG structures.
Currently it's disabled by default.
For the internal test-suite this check it is enabled.
Note: In the case the internal error is detected, debug build with
compile option DEBUG_ENFORCE_POOL_LOCKING helps to catch the source
of the problem.
Implementation described in doc/lvm2-raid.txt.
Basic support includes:
- ability to create RAID 1/4/5/6 arrays
- ability to delete RAID arrays
- ability to display RAID arrays
Notable missing features (not included in this patch):
- ability to clean-up/repair failures
- ability to convert RAID segment types
- ability to monitor RAID segment types
This should be set by default! Normally we have "activation/udev_sync = 1"
in lvm.conf (example.conf.in). But if we use lvm2 without any config file
(or without a definition within '--config' option) the DEFAULT_UDEV_SYNC
is used instead. Together with verify_udev_operations=0 (when we rely on
udev fully), this can cause races as the node could be missing when needed.
(See also https://bugzilla.redhat.com/show_bug.cgi?id=723144)
We've used udev fallback code till now to check whether udev
created/removed the entries in /dev correctly and if not,
a repair was done (giving a warning messagea about that).
This patch adds a possibility to enable this additional check
and subsequent fallback only when required (debugging purposes
mostly) and trust udev completely.
So let's disable the fallback code by default and add a new
configuration option "activation/udev_fallback".
(The original code for creating the nodes will still be used
in case the device directory that is set in lvm.conf differs
from the one that udev uses and also when activation/udev_rules
is set to 0 - otherwise we would end up with no nodes/symlinks
at all)
Also, add a new 'obtain_device_list_from_udev' setting to lvm.conf with which
we can turn this feature on or off if needed.
If set, the cache of block device nodes with all associated symlinks
will be constructed out of the existing udev database content.
This avoids using and opening any inapplicable non-block devices or
subdirectories found in the device directory. This setting is applied
to udev-managed device directory only, other directories will be scanned
fully. LVM2 needs to be compiled with udev support for this setting to
take effect. N.B. Any device node or symlink not managed by udev in
udev directory will be ignored with this setting on.
There is a lot to test.
Two new config settings added that are intended to make the code behave
closely to the way it did before - worth a try if you find problems.
to lvm.conf in the activation section: 'snapshot_autoextend_threshold' and
'snapshot_autoextend_percent', that define how to handle automatic snapshot
extension. The former defines when the snapshot should be extended: when its
space usage exceeds this many percent. The latter defines how much extra space
should be allocated for the snapshot, in percent of its current size.
Add "devices/default_data_alignment" to lvm.conf to control the internal
default that LVM2 uses: 0==64k, 1==1MB, 2==2MB, etc.
If --dataalignment (or lvm.conf's "devices/data_alignment") is specified
then it is always used to align the start of the data area. This means
the md_chunk_alignment and data_alignment_detection are disabled if set.
(Same now applies to pvcreate --dataalignmentoffset, the specified value
will be used instead of the result from data_alignment_offset_detection)
set_pe_align() still looks to use the determined default alignment
(based on lvm.conf's default_data_alignment) if the default is a
multiple of the MD or topology detected values.
The new standard in the storage industry is to default alignment of data
areas to 1MB. fdisk, parted, and mdadm have all been updated to this
default.
Update LVM to align the PV's data area start (pe_start) to 1MB. This
provides a more useful default than the previous default of 64K (which
generally ended up being a 192K pe_start once the first metadata area
was created).
Before this patch:
# pvs -o name,vg_mda_size,pe_start
PV VMdaSize 1st PE
/dev/sdd 188.00k 192.00k
After this patch:
# pvs -o name,vg_mda_size,pe_start
PV VMdaSize 1st PE
/dev/sdd 1020.00k 1.00m
The heuristic for setting the default alignment for LVM data areas is:
- If the default value (1MB) is a multiple of the detected alignment
then just use the default.
- Otherwise, use the detected value.
In practice this means we'll almost always use 1MB -- that is unless:
- the alignment was explicitly specified with --dataalignment
- or MD's full stripe width, or the {minimum,optimal}_io_size exceeds
1MB
- or the specified/detected value is not a power-of-2
Introduce --norestorefile to allow user to override the new requirement.
This can also be overridden with "devices/require_restorefile_with_uuid"
in lvm.conf -- however the default is 1.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Allow metadataignore flag to be passed in to pvcreate.
Ideally, more refactoring of the mda allocation / initialization
is warranted, but for now, we just add another parameter to 'add_mda'
to take an existing mda ignored flag. We need to do this or pv_write
loses the state of the mda 'ignored' flag before copying and writing
to disk.
Add a field to struct volume_group to later implement metadata
balancing:
- mda_copies: target # of non-ignored mdas in the VG; default 0 (do
not control pv 'ignore mdas' bit.
This patch just adds the parameter to the structures with the default
values but does not modify any commands. Should be no functional change.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
This patch adds a new implementation of locking function instead
of mlockall() that may lock way too much memory (>100MB).
New function instead uses mlock() system call and selectively locks
memory areas from /proc/self/maps trying to avoid locking areas
unused during lock-ed state.
Patch also adds struct cmd_context to all memlock() calls to have
access to configuration.
For backward compatibility functionality of mlockall()
is preserved with "activation/use_mlockall" flag.
As a simple check, locking and unlocking counts the amount of memory
and compares whether values are matching.
the background polldaemon is allowed to start. It can be used
standalone or in conjunction with --refresh or --available y.
Control over when the background polldaemon starts will be particularly
important for snapshot-merge of a root filesystem.
Dracut will be updated to activate all LVs with: --poll n
The lvm2-monitor initscript will start polling with: --poll y
NOTE: Because we currently have no way of knowing if a background
polldaemon is active for a given LV the following limitations exist and
have been deemed acceptable:
1) it is not possible to stop an active polldaemon; so the lvm2-monitor
initscript doesn't stop running polldaemon(s)
2) redundant polldaemon instances will be started for all specified LVs
if vgchange or lvchange are repeatedly used with '--poll y'
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Add configure --enable-units-compat to set si_unit_consistency off by default.
Use standard output units for 'PE Size' and 'Stripe size' in pv/lvdisplay.
Adds 'data_alignment_detection' config option to the devices section of
lvm.conf. If your kernel provides topology information in sysfs (linux
>= 2.6.31) for the Physical Volume, the start of data area will be
aligned on a multiple of the ’minimum_io_size’ or ’optimal_io_size’
exposed in sysfs.
minimum_io_size is used if optimal_io_size is undefined (0). If both
md_chunk_alignment and data_alignment_detection are enabled the result
of data_alignment_detection is used.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
If the pvcreate --dataalignmentoffset option is not specified the start
of a PV's aligned data area will be shifted by the associated
'alignment_offset' exposed in sysfs (unless
devices/data_alignment_offset_detection is disabled in lvm.conf).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
