mirror of
git://sourceware.org/git/lvm2.git
synced 2024-10-26 17:25:10 +03:00
36cac41115
Commitsa29bb6a14b...5c199d99f4narrowed down on addressing the escaping of hyphens in the dynamic creation of manuals whilst avoiding them in creating help texts. This lead to a sequence of slipping through hyphens adrressed by additional patches in aforementioned commit series. On the other hand, postprocessing dynamically man-generator created and statically provided manuals catches all hyphens in need of escaping. Changes: - revert the above commits whilst keeping man-generator streamlining and the detection of any '\' when generating help texts in order to avoid escapes to slip in - Dynamically escape hyphens in manaual pages using sed(1) in the respective Makefile targets - remove any manually added escaping on hyphens from any static manual sources or headers
213 lines
5.7 KiB
Plaintext
213 lines
5.7 KiB
Plaintext
.TH DMFILEMAPD 8 "Dec 17 2016" "Linux" "MAINTENANCE COMMANDS"
|
|
|
|
.de OPT_FD
|
|
. RB [ file_descriptor ]
|
|
..
|
|
.
|
|
.de OPT_GROUP
|
|
. RB [ group_id ]
|
|
..
|
|
.de OPT_PATH
|
|
. RB [ abs_path ]
|
|
..
|
|
.
|
|
.de OPT_MODE
|
|
. RB [ mode ]
|
|
..
|
|
.
|
|
.de OPT_DEBUG
|
|
. RB [ foreground [ verbose ] ]
|
|
..
|
|
.
|
|
.SH NAME
|
|
.
|
|
dmfilemapd \(em device-mapper filemap monitoring daemon
|
|
.
|
|
.SH SYNOPSIS
|
|
.
|
|
.de CMD_DMFILEMAPD
|
|
. ad l
|
|
. IR dmfilemapd
|
|
. OPT_FD
|
|
. OPT_GROUP
|
|
. OPT_PATH
|
|
. OPT_MODE
|
|
. OPT_DEBUG
|
|
. ad b
|
|
..
|
|
.CMD_DMFILEMAPD
|
|
.
|
|
.PD
|
|
.ad b
|
|
.
|
|
.SH DESCRIPTION
|
|
.
|
|
The dmfilemapd daemon monitors groups of \fIdmstats\fP regions that
|
|
correspond to the extents of a file, adding and removing regions to
|
|
reflect the changing state of the file on-disk.
|
|
|
|
The daemon is normally launched automatically by the \fPdmstats
|
|
create\fP command, but can be run manually, either to create a new
|
|
daemon where one did not previously exist, or to change the options
|
|
previously used, by killing the existing daemon and starting a new
|
|
one.
|
|
.
|
|
.SH OPTIONS
|
|
.
|
|
.HP
|
|
.BR file_descriptor
|
|
.br
|
|
Specify the file descriptor number for the file to be monitored.
|
|
The file descriptor must reference a regular file, open for reading,
|
|
in a local file system that supports the FIEMAP ioctl, and that
|
|
returns data describing the physical location of extents.
|
|
|
|
The process that executes \fBdmfilemapd\fP is responsible for
|
|
opening the file descriptor that is handed to the daemon.
|
|
.
|
|
.HP
|
|
.BR group_id
|
|
.br
|
|
The \fBdmstats\fP group identifier of the group that \fBdmfilemapd\fP
|
|
should update. The group must exist and it should correspond to
|
|
a set of regions created by a previous filemap operation.
|
|
.
|
|
.HP
|
|
.BR abs_path
|
|
.br
|
|
The absolute path to the file being monitored, at the time that
|
|
it was opened. The use of \fBpath\fP by the daemon differs,
|
|
depending on the filemap following mode in use; see \fBMODES\fP
|
|
and the \fBmode\fP option for more information.
|
|
|
|
.br
|
|
.HP
|
|
.BR mode
|
|
.br
|
|
The filemap monitoring mode the daemon should use: either "inode"
|
|
(\fBDM_FILEMAP_FOLLOW_INODE\fP), or "path"
|
|
(\fBDM_FILEMAP_FOLLOW_PATH\fP), to enable follow-inode or
|
|
follow-path mode respectively.
|
|
.
|
|
.HP
|
|
.BR [foreground]
|
|
.br
|
|
If set to 1, disable forking and allow the daemon to run in the
|
|
foreground.
|
|
.
|
|
.HP
|
|
.BR [verbose]
|
|
Control daemon logging. If set to zero, the daemon will close all
|
|
stdio streams and run silently. If \fBverbose\fP is a number
|
|
between 1 and 3, stdio will be retained and the daemon will log
|
|
messages to stdout and stderr that match the specified verbosity
|
|
level.
|
|
.
|
|
.
|
|
.SH MODES
|
|
.
|
|
The file map monitoring daemon can monitor files in two distinct
|
|
ways: the mode affects the behaviour of the daemon when a file
|
|
under monitoring is renamed or unlinked, and the conditions which
|
|
cause the daemon to terminate.
|
|
|
|
In both modes, the daemon will always shut down when the group
|
|
being monitored is deleted.
|
|
|
|
.P
|
|
.B Follow inode
|
|
.P
|
|
The daemon follows the inode of the file, as it was at the time the
|
|
daemon started. The file descriptor referencing the file is kept
|
|
open at all times, and the daemon will exit when it detects that
|
|
the file has been unlinked and it is the last holder of a reference
|
|
to the file.
|
|
|
|
This mode is useful if the file is expected to be renamed, or moved
|
|
within the file system, while it is being monitored.
|
|
|
|
.P
|
|
.B Follow path
|
|
.P
|
|
The daemon follows the path that was given on the daemon command
|
|
line. The file descriptor referencing the file is re-opened on each
|
|
iteration of the daemon, and the daemon will exit if no file exists
|
|
at this location (a tolerance is allowed so that a brief delay
|
|
between removal and replacement is permitted).
|
|
|
|
This mode is useful if the file is updated by unlinking the original
|
|
and placing a new file at the same path.
|
|
.
|
|
.SH LIMITATIONS
|
|
.
|
|
The daemon attempts to maintain good synchronisation between the file
|
|
extents and the regions contained in the group, however, since the
|
|
daemon can only react to new allocations once they have been written,
|
|
there are inevitably some IO events that cannot be counted when a
|
|
file is growing, particularly if the file is being extended by a
|
|
single thread writing beyond EOF (for example, the \fBdd\fP program).
|
|
|
|
There is a further loss of events in that there is currently no way
|
|
to atomically resize a \fBdmstats\fP region and preserve its current
|
|
counter values. This affects files when they grow by extending the
|
|
final extent, rather than allocating a new extent: any events that
|
|
had accumulated in the region between any prior operation and the
|
|
resize are lost.
|
|
|
|
File mapping is currently most effective in cases where the majority
|
|
of IO does not trigger extent allocation. Future updates may address
|
|
these limitations when kernel support is available.
|
|
.
|
|
.SH EXAMPLES
|
|
.
|
|
Normally the daemon is started automatically by the \fBdmstats\fP
|
|
\fBcreate\fP or \fBupdate_filemap\fP commands but it can be run
|
|
manually for debugging or testing purposes.
|
|
.P
|
|
Start the daemon in the background, in follow-path mode
|
|
.br
|
|
#
|
|
.B dmfilemapd 3 0 /srv/images/vm.img path 0 0 3< /srv/images/vm.img
|
|
.br
|
|
.P
|
|
Start the daemon in follow-inode mode, disable forking and enable
|
|
verbose logging
|
|
.br
|
|
#
|
|
.B dmfilemapd 3 0 /var/tmp/data inode 1 3 3< /var/tmp/data
|
|
.br
|
|
Starting dmfilemapd with fd=3, group_id=0 mode=inode, path=/var/tmp/data
|
|
.br
|
|
dm version [ opencount flush ] [16384] (*1)
|
|
.br
|
|
dm info (253:0) [ opencount flush ] [16384] (*1)
|
|
.br
|
|
dm message (253:0) [ opencount flush ] @stats_list dmstats [16384] (*1)
|
|
.br
|
|
Read alias 'data' from aux_data
|
|
.br
|
|
Found group_id 0: alias="data"
|
|
.br
|
|
dm_stats_walk_init: initialised flags to 4000000000000
|
|
.br
|
|
starting stats walk with GROUP
|
|
.br
|
|
exiting _filemap_monitor_get_events() with deleted=0, check=0
|
|
.br
|
|
Waiting for check interval
|
|
.br
|
|
.P
|
|
.
|
|
.SH AUTHORS
|
|
.
|
|
Bryn M. Reeves <bmr@redhat.com>
|
|
.
|
|
.SH SEE ALSO
|
|
.
|
|
.BR dmstats (8)
|
|
|
|
LVM2 resource page: https://www.sourceware.org/lvm2/
|
|
.br
|
|
Device-mapper resource page: http://sources.redhat.com/dm/
|
|
.br
|