Provided by: rsbackup_8.0-1build3_amd64 bug

NAME

       /etc/rsbackup/config - configuration for rsync-based backup utility

DESCRIPTION

       This describes the configuration file syntax for for rsbackup(1).

SYNTAX

   Line Splitting
       Line  are  split  into space-separated words.  To include spaces in a word, quote it using
       "double  quotes".   Quotes  and  backslashes  within  quoted  strings  are  escaped   with
       backslashes (and cannot appear in an unquoted word).

   Comments and Blank Lines
       Anything after the first (unquoted) "#" to appear on a line is ignored.

       Lines with no words on (whether they are completely empty, or contain just spaces, or have
       a "#" before any non-space characters)  are  ignored  (and  do  not  have  to  follow  the
       indentation rules below).

   Directives and Stanzas
       The  first  word  of  a  line  is called a directive.  The remaining words if any form its
       arguments.

       A stanza consists of  a  directive  introducing  the  stanza  followed  by  zero  or  more
       directives  within  the  stanza.   These  must  be indented, consistently, relative to the
       directive that introduced the stanza.

       A configuration file contains global directives (which must not be indented)  and  one  or
       more host stanzas.  Each host stanza contains one or more volume stanzas.

       Global directives may appear after host stanzas (and host directives after volume stanzas)
       provided they are indented correctly.

   Time Intervals
       A time interval, denoted INTERVAL below, can be either a raw integer, or an  integer  with
       the suffix "s", "m", "h" or "d" for seconds, hours, minutes or days respectively.

       If there is no suffix then the interpretation is contextual.  This behavior is deprecated;
       suffixes will become mandatory in future.

GLOBAL DIRECTIVES

       Global directives control some general aspect of the program.

       database PATH
              The path to the backup database.  By default this is LOGS/backups.db where LOGS  is
              controlled by the logs directive below.

       device DEVICE
              Names  a  device.   This  can  be  used multiple times.  The store must have a file
              called STORE/device-id which contains a known device name.  Backups  will  only  be
              made to known devices.

              When  a  device  is  lost  or  destroyed,  remove  its  device  entry  and  use the
              --prune-unknown option to delete records of backups on it.

              Device names may contain letters, digits, dots and underscores.

       include PATH
              Include another file as part of the configuration.  If PATH is a directory then the
              files within it are included (excluding dotfiles, backup and recovery files).

       keep-prune-logs INTERVAL
              The time period to keep records of pruned backups for.  The default is 31 days.

       lock PATH
              Enable  locking.  If this directive is present then PATH will be used as a lockfile
              for operations that change anything (--backup, --prune, etc).

              The lock is made by opening PATH and calling flock(2) on it with LOCK_EX.

       logs PATH
              The  directory  to  store  logfiles   and   backup   records.    The   default   is
              /var/log/backup.

       post-access-hook COMMAND...

       post-device-hook COMMAND...
              A  command to execute after all backup and prune operations.  This is executed only
              once per invocation of rsbackup.  A backup is still considered  to  have  succeeded
              even if the post-access hook fails (i.e. exits nonzero).  See HOOKS below.

       pre-access-hook COMMAND...

       pre-device-hook COMMAND...
              A  command to execute before anything that accesses any backup devices (i.e. backup
              and prune operations).  This is executed only once per invocation of  rsbackup  and
              if  it  fails (i.e. exits nonzero) then rsbackup terminates immediately.  See HOOKS
              below.

       prune-timeout INTERVAL
              The maximum amount of time to spend pruning, in a single invocation.  0 means  that
              there is no limit (which is the default).

              Note that, if this is directive is used, prune operations timing out are considered
              to be normal behavior, and the exit status will be  0.   Most  of  the  diagnostics
              relating to timeouts are suppressed unless the -v option is used.

       public true|false
              If  true,  backups  are  public.   Normally  backups must only be accessible by the
              calling user.  This directive suppresses the check.

       store [--mounted|--no-mounted] PATH
              A path at which a backup device may be mounted.  This can be used multiple times.

              With the --mounted option (which is the default), PATH must be a mount point.  With
              --no-mounted it need not be a mount point.

       store-pattern [-mounted|-nomounted] PATTERN
              A glob(7) pattern matching paths at which a backup device may be mounted.  This can
              be used multiple times.

              See the description of store above for the meanings of the options.

   Report Directives
       These are global directives that affect only the HTML report.

       color-bad COLOR
              The color used to represent bad states  (no  sufficiently  recent  backup)  in  the
              report.  See below for the interpretation of COLOR.

       color-good COLOR
              The color used to represent good states (a recent backup) in the report.

       report [+] [KEY][:VALUE][?CONDITION] ...
              Defines  the  report  contents.   The arguments to this directive are a sequence of
              keys, optionally parameterized by a value and/or a condition.

              If the first argument  is  a  +  then  the  arguments  are  added  to  the  current
              configuration; otherwise they replace it.

              The possible keys, with values where appropriate, are:

              generated
                     A timestamp stating when the report was generated.

              history-graph
                     A graphic showing the backups available for each volume.  This only works if
                     rsbackup-graph(1) is installed.

              h1:HEADING

              h2:HEADING

              h3:HEADING
                     Headings at levels 1, 2 and 3.

              logs   A list of logs of failed backups.

              p:PARAGRAPH
                     A paragraph of text.

              prune-logs[:DAYS]
                     A list of logs of pruned backups.

                     DAYS is the number of days of pruning  logs  to  put  in  the  report.   The
                     default is 3.

              summary
                     A table summarizing the backups available for each volume.

              title:TITLE
                     The document title.

              warnings
                     A list of warning messages.

              If  a  condition  is  specified then the key is only used if the condition is true.
              The possible conditions are:

              warnings
                     True if there are any warnings to display  (i.e.  if  the  warnings  key  is
                     nonempty).

              Within a VALUE the following sequences undergo substitution:

              \CHAR  Replaced with the single character CHAR.

              ${VARIABLE}
                     Replaced with the value of the environment variable VARIABLE, if it is set.

              The following environment variables are set:

              RSBACKUP_CTIME
                     The local date and time in ctime(3) format.

              RSBACKUP_DATE
                     The local date in YYYY-MM-DD format.

              The default is equivalent to:

                         report "title:Backup report (${RSBACKUP_DATE})"
                         report + "h1:Backup report (${RSBACKUP_DATE})"
                         report + h2:Warnings?warnings warnings
                         report + "h2:Summary" summary
                         report + history-graph
                         report + h2:Logfiles logs
                         report + "h3:Pruning logs" prune-logs
                         report + "p:Generated ${RSBACKUP_CTIME}"

       sendmail PATH
              The  path  to  the  executable  to use for sending email.  The default is platform-
              dependent but typically /usr/sbin/sendmail.  The executable should support the  -t,
              -oee, -oi and -odb options.

       stylesheet PATH
              The  path  to  the  stylesheet to use in the HTML report.  If this is absent then a
              built-in default stylesheet is used.

   Graph Directives
       These are global directives that affect the output of rsbackup-graph(1).

       color-graph-background COLOR
              The background color.  See below for the interpretation of COLOR.

       color-graph-foreground COLOR
              The foreground color, i.e. for text.

       color-month-guide COLOR
              The color for the vertical month guides.

       color-host-guide COLOR
              The color for the horizontal guides between hosts.

       color-volume-guide COLOR
              The color for the horizontal guides between volumes.

       device-color-strategy STRATEGY
              The strategy to use for picking device colors.

              A strategy is a name and a sequence of parameters, all of which are optional.

              The possible strategies are:

              equidistant-value HUE SATURATION MINVALUE MAXVALUE
                     Colors are picked with chosen hue and saturation, with values equally spaced
                     within a range.

                     The  default  hue  is  0 and the default saturation is 1.  The default value
                     range is from 0 to 1.

              equidistant-hue HUE SATURATION VALUE
                     Colors are picked with chosen saturation and value and equally spaced  hues,
                     starting from HUE.

                     The default starting hue is 0 and the default saturation and value are 1.

              The default strategy is equivalent to:
                         device-color-strategy equidistant-value 120 0.75

       horizontal-padding PIXELS
              The  number pixels to place between horizontally adjacent elements.  The default is
              8.

       vertical-padding PIXELS
              The number pixels to place between vertically adjacent elements.  The default is 2.

       host-name-font FONT
              The font description used for host names.  See  below  for  the  interpretation  of
              FONT.

       volume-name-font FONT
              The font description used for volume names.

       device-name-font FONT
              The font description used for device names.

       time-label-font FONT
              The font description used for time labels.

       graph-layout [+] PART:COLUMN,ROW[:HV] ...
              Defines the graph layout.

              The arguments to this directive are a sequence of graph component specifications of
              the form PART:COLUMN,ROW[:HV], where:

              PART   The name of this component.  The following parts are recognized:

                     host-labels
                            The host name labels for the graph.  This is expected to  be  in  the
                            same row as content.

                     volume-labels
                            The  volume name labels for the graph.  This is expected to be in the
                            same row as content.

                     content
                            The graph content.

                     time-labels
                            The time labels for the graph.  This is expected to be  in  the  same
                            column as content.

                     device-key
                            The key mapping device names to colors.

              COLUMN The column number for this component.  0 is the leftmost column.

              ROW    The row number for this component.  0 is the top row.

              HV     The (optional) justification specification for this component.  H may be one
                     of the following:

                     L      Left justification.

                     C      Centre justification.

                     R      Right justification.

                     V may be one of the following:

                     T      Top justification.

                     C      Centre justification.

                     B      Bottom justification.

              Parts may be repeated or omitted.

              The default layout is equivalent to:

                         graph-layout host-labels:0,0
                         graph-layout + volume-labels:1,0
                         graph-layout + content:2,0
                         graph-layout + time-labels:2,1
                         graph-layout + device-key:2,3:RC

   Colors
       COLOR may be one of the following:

       DECIMAL or 0xRRGGBB
              An integer value representing  an  RGB  triple.   It  is  most  convenient  to  use
              hexadecimal.  For example, black is 0x000000, red is 0xFF0000, and so on.

       rgb RED GREEN BLUE
              Three numbers in the range 0 to 1 representing red, green and blue components.

       hsv HUE SATURATION VALUE
              HUE  chooses  between  different primary colors and mixtures of them.  0 represents
              red, 120 represents green and 240 represents blue;  intermediate  values  represent
              mixed hues.

              Normally it would be in the range 0 <= HUE < 360, but values outside this range are
              mapped into it.

              SATURATION is a number in the range 0 to 1 and (roughly)  represents  how  colorful
              the color is.  0 is a shade of grey and 1 is maximally colorful.

              VALUE is a number in the range 0 to 1 and represents the brightness of the color.

              See  https://en.wikipedia.org/wiki/HSL_and_HSV  for  a  fuller  discussion of these
              terms.

   Fonts
       FONT is a Pango font description.  The syntax is  "[FAMILY-LIST]  [STYLE-OPTIONS]  [SIZE]"
       where:

       FAMILY-LIST
              A  comma-separate  list  of  font  families.  These necessarily depend on the fonts
              installed locally but Pango recognizes monospace, sans and  and  serif  as  generic
              family names.

              To get a list of Pango fonts:

                  rsbackup-graph --fonts

       STYLE-OPTIONS
              A whitespace-separated list of style, variant, weight, stretch and gravity options.

              The possible style options are roman (the default), oblique and italic.

              The possible variant options are small-caps.

              The possible weight options are thin, ultra-light, light, semi-light, book, regular
              (the default), medium, semi-bold, bold, ultra-bold, heavy and ultra-heavy.

              The  possible  stretch  options  are  ultra-condensed,  condensed,  semi-condensed,
              semi-expanded, expanded and ultra-expanded.

              The possible gravity options are south (the default), north, east and west.

       SIZE   The font size in points, or PIXELSpx for a font size in pixels.

       The  details  of  the syntax are entirely under the control of the Pango library; for full
       details you must consult its documentation or source code.

INHERITABLE DIRECTIVES

       Inheritable directives control an aspect of one or more backups.  They can be specified at
       the  global  level  or in a host or volume stanza (see below).  If one appears in multiple
       places then volume settings override host  settings  and  host  settings  override  global
       settings.

       backup-parameter NAME VALUE
              Set a parameter for the backup policy.  See BACKUP POLICIES below.

       backup-parameter --remove NAME
              Remove a parameter for the backup policy.  See BACKUP POLICIES below.

       backup-policy NAME
              The backup policy to use.  See BACKUP POLICIES below.

       hook-timeout INTERVAL
              How  long to wait before concluding a hook has hung.  The default is 0, which means
              to wait indefinitely.

       host-check always-up
              Assume that the host is always up.

       host-check ssh
              Check whether the host is up using SSH.  This is the default host check behavior.

       host-check command COMMAND...
              Check whether the host is up by executing a command.  The name of the host will  be
              appended  to the command line.  If it exits with status 0 the host is assumed to be
              up.  If it exits with nonzero status the host is assumed to be down.

       max-age INTERVAL
              The maximum age of the most recent  backup  before  you  feel  uncomfortable.   The
              default  is  3  days,  meaning that if a volume hasn't been backed up in the last 3
              days it will have red ink in the HTML report.

       post-backup-hook COMMAND...

       post-volume-hook COMMAND...
              A command to execute after finishing backups of a volume, or after they failed.   A
              backup  is  still  considered  to have succeeded even if the post-backup hook fails
              (exits nonzero).  See HOOKS below.

              The hook can be suppressed with an empty COMMAND (e.g. if you have  a  global  hook
              and which to suppress it for a single volume).

       pre-backup-hook COMMAND...

       pre-volume-hook COMMAND...
              A  command  to  execute  before starting a backups of a volume.  If this hook fails
              (i.e. exits nonzero) then the backups are not made and  the  post-volume-hook  will
              not be run.  See HOOKS below.

              The  hook  can  be suppressed with an empty COMMAND (e.g. if you have a global hook
              and which to suppress it for a single volume).

              This hook can override the source path for the volume by writing a new source  path
              to standard output.

       prune-parameter NAME VALUE
              Set a parameter for the pruning policy.  See PRUNING below.

       prune-parameter --remove NAME
              Remove a parameter for pruning policy.

       prune-policy NAME
              The pruning policy to use.  See PRUNING below.

       backup-job-timeout INTERVAL
              How  long  to wait before concluding rsync has hung.  The default is 0, which means
              to wait indefinitely.

       rsync-command COMMAND
              The command to execute to make a backup.  The default is rsync.

       rsync-base-options OPTIONS ...
              The options to supply to the rsync command.   The  default  is  --archive  --sparse
              --numeric-ids --compress --fuzzy --hard-links --delete --stats.

       rsync-extra-options OPTIONS ...
              Additional options to supply to the rsync command.  The default is --xattrs --acls.

              See  PLATFORMS  for  how  to  use  this  directive when backing up macOS or Windows
              platforms.

       rsync-io-timeout INTERVAL
              The I/O timeout (passed as --timeout) to rsync.   The  default  is  0,  meaning  no
              timeout.

       rsync-link-dest true|false
              If  true,  use rsync's --link-dest option to save space in backups.  The default is
              true.

       rsync-remote COMMAND
              If nonempty, passed to rsync as the --rsync-path option.

       ssh-timeout INTERVAL
              How long to wait before concluding a host is down.  The default is 60 seconds.

HOST DIRECTIVES

       A host stanza is started by a host directive.

       host HOST
              Introduce a host stanza.  The name is used for the backup directory for this host.

       The following directives, and volume stanzas (see below), can appear in a host stanza:

       devices PATTERN
              A glob(3) pattern restricting the devices that this host will be backed up to.

              Note that only backup creation honors this restriction.  Pruning  and  retiring  do
              not.

       group GROUP
              The concurrency group for this host.  The default is the name from the host stanza.
              See CONCURRENCY below.

       hostname HOSTNAME
              The SSH hostname for this host.  The default is the name from the host stanza.

              The hostname localhost is treated specially: it is assumed to always  be  identical
              to the local system, so files will be read from the local filesystem.

       priority INTEGER
              The  priority of this host.  Hosts are backed up in descending priority order.  The
              default priority is 0.

       user USERNAME
              The SSH username for this host.  The default is not to supply a username.

       In addition, inheritable directives  can  appear  in  a  host  stanza,  and  override  any
       appearance of them at the global level.

       The contents of a host stanza must be indented consistently relative to the host directive
       that introduces it.

       Remote hosts are accessed by SSH.  The user rsbackup runs as must be able  to  connect  to
       the  remote  host (and without a password being entered if it is to be run from a cron job
       or similar).

VOLUME DIRECTIVES

       A volume stanza is started by a volume directive.   It  can  only  appear  within  a  host
       stanza.

       volume VOLUME PATH
              Introduce  a  volume  stanza.   The  name is used for the backup directory for this
              volume.  The path is the absolute path on the host.

       The following directives can appear in a volume stanza:

       check-file PATH
              Checks that PATH exists before backing up  the  volume.   PATH  may  be  either  an
              absolute  path  or  a  relative  path  (to the root of the volume).  It need not be
              inside the volume though the usual use would be to check for a file which is always
              present there.

              This  check is done before executing the pre-volume-hook, so it applies to the real
              path to the volume, not the rewritten path.

       check-mounted true|false
              If true, checks that the volume's path is a  mount  point  before  backing  up  the
              volume.

              This  check is done before executing the pre-volume-hook, so it applies to the real
              path to the volume, not the rewritten path.

              Note that if multiple check- options are used, all checks must pass for the  volume
              to be backed up.

       exclude PATTERN
              An exclusion for this volume.  The pattern is passed to the rsync --exclude option.
              This directive may appear multiple times per volume.

              See the rsync man page for full details.

       traverse true|false
              If true, traverse  mount  points.   This  suppresses  the  rsync  --one-file-system
              option.

       In  addition,  inheritable  directives  can  appear  in  a volume stanza, and override any
       appearance of them at the host or global level.

       The contents of a volume stanza must be  indented  consistently  relative  to  the  volume
       directive that introduces it.

BACKUP POLICIES

       Backup policies determine when a backup is made.  The available policies are listed below.
       The default policy is daily.

   always
       This policy creates a backup at every opportunity.

   daily
       This policy creates at most one backup per calendar day, as understood in local time.

   interval
       This policy enfores a minimum interval between backups.  The following  backup  parameters
       are supported:

       min-interval INTERVAL
              The minimum interval between backups.

       The  --force  option can be used to override backup policies, forcing all selected volumes
       to be backed up unconditionally.

PRUNING

       This is process of removing old backups (using the --prune option).   The  pruning  policy
       used  to  determine  which  backups  to  remove  is  set with the inheritable prune-policy
       directive, and parameters to the policy set via the prune-parameter directive.

       The available policies are listed below.  The default policy is age.

   age
       This policy deletes backups older than a minimum age, provided a minimum number of backups
       on a device remain available.  The following pruning parameters are supported:

       min-backups BACKUPS
              The  minimum  number  of  backups of the volume to maintain on the device.  Pruning
              will never cause the number of backups to fall below this value.  The default  (and
              minimum) is 1.

       prune-age INTERVAL
              The  age  after  backups  become eligible for pruning.  Only backups more than this
              many days old will be pruned.  The default is 366 days and the minimum is 1 day.

       For backwards compatibility, these values can also be set using the directives of the same
       name.  This will be disabled in a future version.

   decay
       This policy thins out backups older than a minimum age, using a configurable decay pattern
       that arranges to keep a declining number of backups with age.

       The idea is that backup history is partitioned into a series of windows.  Each window is a
       fixed multiple of the size of the previous one.  The pruning policy arranges that only one
       backup (per device) is preserved within each window.

       For example, with the default configuration, the first window  is  1  day  long  and  will
       contain  one  backup.   The  second  window  is two days long and again, only contains one
       backup.  The third window is four days long, and so on.

       The effect is that the density of backups over time decays exponentially.

       See decay.pdf ⟨https://www.greenend.org.uk/rjk/rsbackup/decay.pdf⟩ for more information.

       The following pruning parameters are supported:

       decay-start INTERVAL
              The age after backups become eligible for pruning.  Only  backups  more  than  this
              many days old will be pruned.  The default is 1 day and the minimum is 1 day.

       decay-limit INTERVAL
              The age after which backups are always pruned.  Backups older than this will always
              be pruned unless this would leave no backups at all.  The default is 366  days  and
              the minimum is 1 day.

       decay-scale SCALE
              The  scale  at  which  the  decay  window  is  expanded.   The default is 2 and the
              (exclusive) minimum is 1.

       decay-window INTERVAL
              The size of the decay window.  The default is 1 day and the minimum is 1 day.

   exec
       This policy executes a subprogram with parameters and additional information  supplied  in
       the environment.

       The following parameters are supported:

       path   The path to the subprogram to execute.

       Any  additional  parameters  are  supplied  to  the  subprogram via environment variables,
       prefixed with PRUNE_.  Additionally the following environment variables are set:

       PRUNE_DEVICE
              The name of the device containing the backup.

       PRUNE_HOST
              The name of the host.

       PRUNE_ONDEVICE
              The list of backups on the device, by timestamp.  This list excludes any that  have
              already been scheduled for pruning.

       PRUNE_TOTAL
              The  total  number  of backups of this volume on any device.  Note that it does not
              include backups on other devices that  have  just  been  selected  for  pruning  by
              another call to the subprogram.

       PRUNE_VOLUME
              The name of the volume.

       These environment variables all override any parameters with clashing names.

       The  output  should be a list of backups to prune, one per line (in any order).  Each line
       should contain the timestamp of the backup to prune (i.e. the same value  as  appeared  in
       PRUNE_ONDEVICE),  followed  by  a  colon, followed by the reason that this backup is to be
       pruned.

       As a convenience, if the argument to prune-policy starts with / then the  exec  policy  is
       chosen with the policy name as the path parameter.

   never
       This policy never deletes any backups.

HOOKS

       A  hook  is  a  command  executed  by rsbackup just before or just after some action.  The
       command is passed directly to execvp(3); to use a shell command, therefore, either wrap it
       in a script or invoke the shell with the -c option.

       All  hooks  are run in --dry-run mode.  Hook scripts must honor RSBACKUP_ACT which will be
       set to false in this mode and true otherwise.

   Device Hooks
       Device hooks are executed (once) before doing anything that  will  access  backup  devices
       (even just to read them).

       The following environment variables are set when a device hook is executed:

       RSBACKUP_ACT
              Set to false in --dry-run mode and true otherwise.

       RSBACKUP_DEVICES
              A space-separated list of known device names.

       RSBACKUP_HOOK
              The name of the hook (i.e. pre-device-hook, etc).  This allows a single hook script
              to serve as the implementation for multiple hooks.

       Device hooks used to be called access hooks.

   Volume Hooks
       Pre-volume hooks are executed before all the backups of a volume,  and  post-volume  hooks
       after  all  backups  of  the  volume.  Possible uses for volume hooks include snapshotting
       volumes or mounting volumes.

       When a volume hook is executed, the environment variables listed in ENVIRONMENT below  are
       set, along with the following:

       RSBACKUP_HOOK
              The name of the hook (i.e. pre-volume-hook, etc).  This allows a single hook script
              to serve as the implementation for multiple hooks.

       The exit status of the pre-volume-hook is interpreted as follows:

       0      The hook succeeded.  The backup will be attempted.

       75     The volume is temporarily unavailable.  The backup will not  be  attempted,  as  if
              check-file or check-mounted had failed.

       anything else
              Something  went  wrong.   The  backup  will be treated as failed, as if it had been
              attempted and rsync had failed.

       See rsbackup-snapshot-hook(1) for a hook program that can be used to back  up  from  Linux
       LVM snapshots.

       Volume hooks used to be called backup hooks.

ENVIRONMENT

       When a hook or rsync are executed, the following environment variables are set:

       RSBACKUP_ACT
              Set to false in --dry-run mode and true otherwise.

       RSBACKUP_HOST
              The name of the host.

       RSBACKUP_GROUP
              The name of the concurrency group.  See the group directive.

       RSBACKUP_SSH_HOSTNAME
              The SSH hostname of the host.

              Recall  that  rsbackup  treats  the hostname localhost specially.  If the hook also
              needs to do so then it must duplicate this logic.

       RSBACKUP_SSH_TARGET
              The SSH hostname and username combined for passing to ssh(1).

              This will be username@hostname or just hostname depending on whether a SSH username
              was set.

       RSBACKUP_SSH_USERNAME
              The  SSH  username of the host.  If no SSH username was set, this variable will not
              be set.

       RSBACKUP_VOLUME
              The name of the volume.

       RSBACKUP_VOLUME_PATH
              The path to the volume.

CONCURRENCY

       Any given device only gets used for one thing at a time; it will  never  happen  that  two
       backups, or two prunes, access the same device.

       No  concurrency  group  will  ever  have  more  than  one  backup made from it any a time.
       Normally a concurrency group is just a single host, but the group directive can be used to
       add multiple hosts to a single group (for instance, if they share physical hardware).

       No  two  hooks  will be executed concurrently, even if they apply to different concurrency
       groups and different devices.  However, a hook may execute while a backup (for a different
       concurrency group and a different device) is executing.

NOTES

   Resource Control
       Large  backup  jobs  can have unreasonable impacts on kernel memory, evicting applications
       and cache data by the gigabyte just for single-use copies of backup data.

       On Linux this problem can be addressed with with the memory cgroup controller.

       First, a slice is created on each host (both the back server and client machines):

           [Unit]
           Description=Memory-bound slice for rsbackup
           Before=slices.target

           [Slice]
           MemoryAccounting=true
           MemoryHigh=128M
           MemoryMax=256M

       Second, rsbackup is run with a memory use limit:

           systemd-run --quiet --pipe --slice membound rsbackup --backup

       If  you  are  using   the   Debian   cron   job   then   this   can   be   configured   in
       /etc/rsbackup/defaults:

           nicely="systemd-run --quiet --pipe --slice membound"

       Finally,  to  control  resource  use  on  client machines, add the following to their host
       sections:

           rsync-remote "systemd-run --quiet --pipe --slice membound rsync"

       See also:  systemd-run(1),  systemctl(1),  systemd.slice(5),  systemd.resource-control(5),
       rsbackup.cron(1).

   macOS
       Apple's rsync has a nonstandard option to enable backup of extended attributes.  For local
       backups you can configure rsbackup to use it with a host-level directive:

           rsync-extra-options --extended-attributes

       If backing up a macOS host from a host with  a  modern  rsync,  or  vice  versa,  however,
       extended  attributes and ACLs cannot be backed up at all.  In that case the affected hosts
       must disable backup attribute and ACL backup as follows:

           rsync-extra-options

       If an up-to-date rsync is used on macOS hosts, it can be left at the default.

   Windows
       rsbackup does not run on Windows.  However, it may be used to back up Windows filesystems.
       In this case it can happen that the attributes in the Windows filesystem do not fit in the
       backup filesystem; if this happens you may see errors like this:

           rsync: rsync_xal_set: lsetxattr(""/backup7/host/volume/2018-02-04/path/to/file"","attrname") failed: No space left on device (28)
           rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1668) [generator=3.1.2]

       In that case the affected volumes must disable attribute backup and ACL backup as follows:

           rsync-extra-options

SEE ALSO

       rsbackup(1),        rsbackup-graph(1),        rsbackup.cron(1),         rsbackup-mount(1),
       rsbackup-snapshot-hook(1), rsync(1), rsbackup(5)

AUTHOR

       Richard Kettlewell <rjk@greenend.org.uk>

                                                                                      rsbackup(5)