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lvm2/daemons
David Teigland f447926e74 device usage based on devices file
The LVM devices file lists devices that lvm can use.  The default
file is /etc/lvm/devices/system.devices, and the lvmdevices(8)
command is used to add or remove device entries.  If the file
does not exist, or if lvm.conf includes use_devicesfile=0, then
lvm will not use a devices file.  An existing but empty file
will cause lvm to see no devices.

When the devices file is in use, the regex filter is not used,
and the filter settings in lvm.conf or the command line are
ignored.

LVM records devices in the devices file using hardware-specific
IDs, such as the WWID, and attempts to use subsystem-specific
IDs for virtual device types (which should ideally be as unique
and stable a hardware-based ID.)  These device IDs are also
written in the VG metadata.  When no hardware or virtual ID is
available, lvm falls back using the unstable device name as the
device ID.  When devnames are used, lvm performs extra scanning
to find devices if their devname changes, e.g. after reboot.

When proper device IDs are used, an lvm command will not look
at devices outside the devices file, but when devnames are used
as a fallback, lvm will scan devices outside the devices file
to locate PVs on renamed devices.  A config setting
search_for_devnames can be used to control the scanning for
renamed devname entries.

Related to the devices file, the new command option
--devices <devnames> allows a specific list of devices to be
exposed to the lvm command, overriding the devices file.
The listed devices act as a sort of devices file in terms
of limiting which devices lvm will see and use.  Devices
that are not listed will appear to be missing to the lvm
command.

Multiple devices files can be kept in /etc/lvm/devices, which
allows lvm to be used with different, independent sets of
devices, e.g. system devices do not need to be exposed to
a specific application, and that application can use lvm on
its own devices that are not exposed to the system.  The
option --devicesfile <filename> is used to select the devices
file to use with the command.  Without the option set, the
default system devices file is used.

Setting --devicesfile "" causes lvm to not use a devices file.
2021-02-22 15:22:33 -06:00
..
cmirrord cmirrord: deamon links libdm 2019-10-04 17:31:55 +02:00
dmeventd lvmcmdlib: lvm2_init_threaded 2020-10-20 22:22:52 +02:00
lvmdbusd lvmdbusd: Bump LVM DBus API version 2020-08-06 13:54:45 -05:00
lvmlockd gcc: ensure pointer is always defined 2021-02-10 15:39:03 +01:00
lvmpolld device usage based on devices file 2021-02-22 15:22:33 -06:00
Makefile.in build: Remove lvmetad leftovers 2018-07-24 15:02:32 +02:00