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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. When the devices file is in use,
the regex filter is not used, and the filter settings in lvm.conf
or on 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. 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 list of devices to be specified for
the command to use, 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 sets of devices, e.g.
system devices do not need to be exposed to a specific application,
and the application can use lvm on its own set of 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.
An existing, empty devices file means lvm will see no devices.
The new command vgimportdevices adds PVs from a VG to the devices
file and updates the VG metadata to include the device IDs.
vgimportdevices -a will import all VGs into the system devices file.
LVM commands run by dmeventd not use a devices file by default,
and will look at all devices on the system. A devices file can
be created for dmeventd (/etc/lvm/devices/dmeventd.devices) If
this file exists, lvm commands run by dmeventd will use it.
Internal implementaion:
- device_ids_read - read the devices file
. add struct dev_use (du) to cmd->use_devices for each devices file entry
- dev_cache_scan - get /dev entries
. add struct device (dev) to dev_cache for each device on the system
- device_ids_match - match devices file entries to /dev entries
. match each du on cmd->use_devices to a dev in dev_cache, using device ID
. on match, set du->dev, dev->id, dev->flags MATCHED_USE_ID
- label_scan - read lvm headers and metadata from devices
. filters are applied, those that do not need data from the device
. filter-deviceid skips devs without MATCHED_USE_ID, i.e.
skips /dev entries that are not listed in the devices file
. read lvm label from dev
. filters are applied, those that use data from the device
. read lvm metadata from dev
. add info/vginfo structs for PVs/VGs (info is "lvmcache")
- device_ids_find_renamed_devs - handle devices with unstable devname ID
where devname changed
. this step only needed when devs do not have proper device IDs,
and their dev names change, e.g. after reboot sdb becomes sdc.
. detect incorrect match because PVID in the devices file entry
does not match the PVID found when the device was read above
. undo incorrect match between du and dev above
. search system devices for new location of PVID
. update devices file with new devnames for PVIDs on renamed devices
. label_scan the renamed devs
- continue with command processing
110 lines
3.9 KiB
C
110 lines
3.9 KiB
C
/*
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* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
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* Copyright (C) 2004-2010 Red Hat, Inc. All rights reserved.
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*
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* This file is part of LVM2.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU Lesser General Public License v.2.1.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef _LVM_PV_H
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#define _LVM_PV_H
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#include "lib/uuid/uuid.h"
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#include "device_mapper/all.h"
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struct device;
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struct format_type;
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struct volume_group;
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struct physical_volume {
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struct id id;
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struct id old_id; /* Set during pvchange -u. */
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struct device *dev;
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const char *device_hint; /* primary name last time metadata was written */
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const char *device_id;
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const char *device_id_type;
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const struct format_type *fmt;
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struct format_instance *fid;
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/*
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* vg_name and vgid are used before the parent VG struct exists.
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* FIXME: Investigate removal/substitution with 'vg' fields.
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*/
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const char *vg_name;
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struct id vgid;
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/*
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* 'vg' is set and maintained when the PV belongs to a 'pvs'
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* list in a parent VG struct.
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*/
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struct volume_group *vg;
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uint64_t status;
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uint64_t size;
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/* bootloader area */
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uint64_t ba_start;
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uint64_t ba_size;
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/* physical extents */
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uint32_t pe_size;
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uint64_t pe_start;
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uint32_t pe_count;
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uint32_t pe_alloc_count;
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uint64_t pe_align;
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uint64_t pe_align_offset;
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/* This is true whenever the represented PV has a label associated. */
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uint64_t is_labelled:1;
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uint64_t unused_missing_cleared:1;
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/* NB. label_sector is valid whenever is_labelled is true */
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uint64_t label_sector;
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struct dm_list segments; /* Ordered pv_segments covering complete PV */
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struct dm_list tags;
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};
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char *pv_fmt_dup(const struct physical_volume *pv);
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char *pv_name_dup(struct dm_pool *mem, const struct physical_volume *pv);
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struct device *pv_dev(const struct physical_volume *pv);
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const char *pv_vg_name(const struct physical_volume *pv);
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char *pv_attr_dup(struct dm_pool *mem, const struct physical_volume *pv);
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const char *pv_dev_name(const struct physical_volume *pv);
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char *pv_uuid_dup(struct dm_pool *mem, const struct physical_volume *pv);
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char *pv_tags_dup(const struct physical_volume *pv);
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char *pv_deviceid_dup(struct dm_pool *mem, const struct physical_volume *pv);
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char *pv_deviceidtype_dup(struct dm_pool *mem, const struct physical_volume *pv);
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uint64_t pv_size(const struct physical_volume *pv);
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uint64_t pv_size_field(const struct physical_volume *pv);
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uint64_t pv_dev_size(const struct physical_volume *pv);
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uint64_t pv_free(const struct physical_volume *pv);
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uint64_t pv_status(const struct physical_volume *pv);
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uint32_t pv_pe_size(const struct physical_volume *pv);
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uint64_t pv_pe_start(const struct physical_volume *pv);
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uint64_t pv_ba_start(const struct physical_volume *pv);
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uint64_t pv_ba_size(const struct physical_volume *pv);
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uint32_t pv_pe_count(const struct physical_volume *pv);
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uint32_t pv_pe_alloc_count(const struct physical_volume *pv);
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uint64_t pv_mda_size(const struct physical_volume *pv);
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struct lvmcache_info;
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uint64_t lvmcache_info_mda_free(struct lvmcache_info *info);
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uint64_t pv_mda_free(const struct physical_volume *pv);
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uint64_t pv_used(const struct physical_volume *pv);
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uint32_t pv_mda_count(const struct physical_volume *pv);
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uint32_t pv_mda_used_count(const struct physical_volume *pv);
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unsigned pv_mda_set_ignored(const struct physical_volume *pv, unsigned mda_ignored);
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int is_orphan(const struct physical_volume *pv);
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int is_missing_pv(const struct physical_volume *pv);
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int is_used_pv(const struct physical_volume *pv);
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int is_pv(const struct physical_volume *pv);
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struct label *pv_label(const struct physical_volume *pv);
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#endif /* _LVM_PV_H */
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