dss-0.0.5.

[dss.git] / dss.ggo

diff --git a/dss.ggo b/dss.ggo
index 03ab294f65515693d325c10f388caf34834a6f04..e473d88446a6be1c4a2cf70d5e3e540a73d09290 100644 (file)
--- a/dss.ggo
+++ b/dss.ggo
@@ -1,6 +1,6 @@
 #
 package "dss"
 #
 package "dss"

-version "0.0.3"
+version "0.0.5"

 purpose "the dyadic snapshot scheduler
 
 dss creates hardlink-based snapshots of a given directory on a remote
 purpose "the dyadic snapshot scheduler
 
 dss creates hardlink-based snapshots of a given directory on a remote


@@ -21,24 +21,36 @@ details="
        configuration file. As usual, if an option is given both at
        the command line and in the configuration file, the command
        line option takes precedence.
        configuration file. As usual, if an option is given both at
        the command line and in the configuration file, the command
        line option takes precedence.

+
+       However, there is an important exception to this rule:
+       If the --run option was given (see below) then dss honors
+       SIGHUP and re-reads its configuration file whenever it
+       receives this signal. In this case the options in the config
+       file override any options that were previously given at the
+       command line. This allows to change the configuration of a
+       running dss process on the fly by sending SIGHUP.

 "
 
 option "daemon" d
 #~~~~~~~~~~~~~~~~
 "
 
 option "daemon" d
 #~~~~~~~~~~~~~~~~

-"run as background daemon"
+"Run as background daemon"

 flag off
 dependon="logfile"
 details="
        Note that dss refuses to start in daemon mode if no logfile
 flag off
 dependon="logfile"
 details="
        Note that dss refuses to start in daemon mode if no logfile

-       was specified.
+       was specified. This option is mostly useful in conjuction
+       with the -R option described below.
+
+       Note that it is not possible to change whether dss runs as
+       background daemon by sending SIGHUP.

 "
 
 option "dry-run" D
 #~~~~~~~~~~~~~~~~~
 "
 
 option "dry-run" D
 #~~~~~~~~~~~~~~~~~

-"only print what would be done"
+"Only print what would be done"

 flag off
 details="
 flag off
 details="

-       This flag does not makes sense for all commands. The run
+       This flag does not make sense for all commands. The run

        command refuses to start if this option was given. The ls
        command silently ignores this flag.
 "
        command refuses to start if this option was given. The ls
        command silently ignores this flag.
 "


@@ -49,17 +61,17 @@ section "Logging"
 
 option "loglevel" l
 #~~~~~~~~~~~~~~~~~~
 
 option "loglevel" l
 #~~~~~~~~~~~~~~~~~~

-"set loglevel (0-6)"
+"Set loglevel (0-6)"

 int typestr="level"
 default="3"
 optional
 details="
 int typestr="level"
 default="3"
 optional
 details="

-       Lower values mean less verbose logging.
+       Lower values mean more verbose logging.

 "
 
 option "logfile" -
 #~~~~~~~~~~~~~~~~~
 "
 
 option "logfile" -
 #~~~~~~~~~~~~~~~~~

-"logfile for the dss daemon process"
+"Logfile for the dss daemon process"

 string typestr="filename"
 optional
 details="
 string typestr="filename"
 optional
 details="


@@ -70,22 +82,24 @@ details="
 defgroup "command"
 #=================
 groupdesc="
 defgroup "command"
 #=================
 groupdesc="

-       dss supports a couple of commands each of which corresponds to a different
-       command line option. Exactly one of these options must be given.
+       dss supports a couple of commands each of which corresponds
+       to a different command line option. Exactly one of these
+       options must be given.

 "
 required
 
 groupoption "create" C
 #~~~~~~~~~~~~~~~~~~~~~
 "
 required
 
 groupoption "create" C
 #~~~~~~~~~~~~~~~~~~~~~

-"create a new snapshot"
+"Create a new snapshot"

 group="command"
 details="
 group="command"
 details="

-       Execute the rsync command to create a new snapshot.Mote that this
-       command does not care about free disk space.
+       Execute the rsync command to create a new snapshot. Note that
+       this command does not care about free disk space.

 "
 "

+

 groupoption "prune" P
 #~~~~~~~~~~~~~~~~~~~~
 groupoption "prune" P
 #~~~~~~~~~~~~~~~~~~~~

-"remove a redundant snapshot"
+"Remove a redundant snapshot"

 group="command"
 details="
        A snapshot is considered redundant if it ether belongs to
 group="command"
 details="
        A snapshot is considered redundant if it ether belongs to


@@ -96,17 +110,17 @@ details="
 
 groupoption "ls" L
 #~~~~~~~~~~~~~~~~~
 
 groupoption "ls" L
 #~~~~~~~~~~~~~~~~~

-"print a list of all snapshots"
+"Print a list of all snapshots"

 group="command"
 details="
 group="command"
 details="

-       The list will contain all snapshots not matter of their state,
-       i.e. incomplete snapshots and snapshots being deleted will
+       The list will contain all snapshots no matter of their state,
+       i. e. incomplete snapshots and snapshots being deleted will

        also be listed.
 "
 
 groupoption "run" R
 #~~~~~~~~~~~~~~~~~~
        also be listed.
 "
 
 groupoption "run" R
 #~~~~~~~~~~~~~~~~~~

-"start creating and pruning snapshots"
+"Start creating and pruning snapshots"

 group="command"
 details="
        This is the main mode of operation. Snapshots will be created
 group="command"
 details="
        This is the main mode of operation. Snapshots will be created


@@ -117,35 +131,35 @@ details="
 section "Rsync-related options"
 ###############################
 
 section "Rsync-related options"
 ###############################
 

-option "remote-user" U
+option "remote-host" H

 #~~~~~~~~~~~~~~~~~~~~~
 #~~~~~~~~~~~~~~~~~~~~~

-"remote user name (default: current user)"
-string typestr="username"
+"Remote host"
+string typestr="hostname"
+default="localhost"

 optional
 details="
 optional
 details="

-       If a user is specified that differs from the user running
-       dss, then rsync will use ssh for taking snapshots.  This will
-       only work if you set up a key-pair to allow rsync to proceed
-       without asking for passwords.
+       If this option is given and its value differs from the local
+       host, then rsync uses ssh. Make sure there is no password
+       needed for the ssh connection. To achieve that, use public key
+       authentication for ssh and, if needed, set the remote user name
+       by using the --remote-user option.

 "
 
 "
 

-option "remote-host" H
+option "remote-user" U

 #~~~~~~~~~~~~~~~~~~~~~
 #~~~~~~~~~~~~~~~~~~~~~

-"remote host"
-string typestr="hostname"
-default="localhost"
+"Remote user name (default: current user)"
+string typestr="username"

 optional
 details="
 optional
 details="

-       If this option is given and its value differs from the local
-       host, then rsync uses ssh, so make sure the user running dss
-       does not need a password to connect to the remote host.
+       Set this if the user running dss is different from the
+       user at the remote host when using ssh.

 "
 
 option "source-dir" -
 #~~~~~~~~~~~~~~~~~~~~
 "
 
 option "source-dir" -
 #~~~~~~~~~~~~~~~~~~~~

-"the data directory"
+"The data directory"

 string typestr="dirname"
 string typestr="dirname"

-optional
+required

 details="
        The directory on the remote host from which snapshots are
        taken.  Of course, the user specified as --remote-user must
 details="
        The directory on the remote host from which snapshots are
        taken.  Of course, the user specified as --remote-user must


@@ -154,9 +168,9 @@ details="
 
 option "dest-dir" -
 #~~~~~~~~~~~~~~~~~~
 
 option "dest-dir" -
 #~~~~~~~~~~~~~~~~~~

-"snapshot dir"
+"Snapshot dir"

 string typestr="dirname"
 string typestr="dirname"

-optional
+required

 details="
        The destination directory on the local host where snapshots
        will be written. This must be writable by the user who runs
 details="
        The destination directory on the local host where snapshots
        will be written. This must be writable by the user who runs


@@ -165,7 +179,7 @@ details="
 
 option "rsync-option" O
 #~~~~~~~~~~~~~~~~~~~~~~
 
 option "rsync-option" O
 #~~~~~~~~~~~~~~~~~~~~~~

-"further rsync options"
+"Further rsync options"

 string typestr="option"
 optional
 multiple
 string typestr="option"
 optional
 multiple


@@ -174,51 +188,37 @@ details="
        to that option are passed verbatim to the rsync command.
 "
 
        to that option are passed verbatim to the rsync command.
 "
 

-option "exclude-patterns" e
-#~~~~~~~~~~~~~~~~~~~~~~~~~~
-"rsync exclude patterns"
-string typestr="path"
-optional
-

 ###################
 section "Intervals"
 ###################
 
 option "unit-interval" u
 #~~~~~~~~~~~~~~~~~~~~~~~
 ###################
 section "Intervals"
 ###################
 
 option "unit-interval" u
 #~~~~~~~~~~~~~~~~~~~~~~~

-"the duration of a unit interval"
+"The duration of a unit interval"

 int typestr="days"
 default="4"
 optional
 details="
 int typestr="days"
 default="4"
 optional
 details="

-       dss snapshot aging is implemented in terms of intervals. There are
-       two command line options related to intervals: the duration of a
-       \"unit\" interval and the number of those unit intervals.
-
-       dss removes any snapshots older than the given number of intervals
-       times the duration of an unit interval and tries to keep the following
-       number of snapshots per interval:
-
-               interval number         number of snapshots
-               ===============================================
-               0                       2 ^ (num-intervals - 1)
-               1                       2 ^ (num-intervals - 2)
-               2                       2 ^ (num-intervals - 3)
-               ...
-               num-intervals - 2                       2
-               num-intervals - 1                       1
-               num-intervals                           0
-
-       In other words, the oldest snapshot will at most be unit_interval *
-       num_intervals old (= 5 days * 4 = 20 days if default values are used).
-       Moreover, there are at most 2^num_intervals - 1 snapshots in total
-       (i.e. 31 by default).  Observe that you have to create at least
-       2 ^ (num_intervals - 1) snapshots each interval for this to work out.
+       dss snapshot aging is implemented in terms of intervals. There
+       are two command line options related to intervals: the
+       duration u of a \"unit\" interval and the number n of those
+       unit intervals.
+
+       dss removes any snapshots older than n times u and tries to
+       keep 2^(k-1) snapshots in interval k, where the interval number
+       k counts from zero, zero being the most recent unit interval.
+
+       In other words, the oldest snapshot will at most be u * n days
+       (= 20 days if default values are used) old.  Moreover, there
+       are at most 2^n - 1 snapshots in total (i. e. 31 by default).
+       Observe that you have to create at least 2 ^ (n - 1) snapshots
+       each interval for this to work out because that is the number
+       of snapshots in interval zero.

 "
 
 option "num-intervals" n
 #~~~~~~~~~~~~~~~~~~~~~~~
 "
 
 option "num-intervals" n
 #~~~~~~~~~~~~~~~~~~~~~~~

-"the number of unit intervals"
+"The number of unit intervals"

 int typestr="num"
 default="5"
 optional
 int typestr="num"
 default="5"
 optional


@@ -231,61 +231,85 @@ option "pre-create-hook" r
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "Executed before snapshot creation"
 string typestr="command"
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "Executed before snapshot creation"
 string typestr="command"

-default="/bin/true"

 optional
 details="
        Execute this command before trying to create a new snapshot.
 optional
 details="
        Execute this command before trying to create a new snapshot.

-       If this command returns with a non-zero exit status, do not
-       perform the backup. One possible application of this is to
-       return non-zero during office hours in order to not slow down
-       the file systems by taking snapshots.
-"
+       If this command returns with a non-zero exit status, no
+       snapshot is being created and the operation is retried later.
+
+       For example, one might want to execute a script that checks
+       whether all snapshot-related file systems are properly mounted.

 
 

+       Another possible application of this is to return non-zero
+       during office hours in order to not slow down the file systems
+       by taking snapshots.
+"

 
 option "post-create-hook" o
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "Executed after snapshot creation"
 string typestr="command"
 
 option "post-create-hook" o
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "Executed after snapshot creation"
 string typestr="command"

-default="/bin/true"

 optional
 details="
 optional
 details="

-       Execute this after a snapshot has successfully been created
-       The return value on the command is ignored. For instance one
-       could count the number of files per user and/or the disk
-       usage patterns in order to store them in a database for
-       further treatment.
+       Execute this after a snapshot has successfully been
+       created. The full path of the newly created snapshot is passed
+       to the hook as the first argument.  The return value of that
+       hook is ignored.
+
+       For instance this hook can be used to count the number of
+       files per user and/or the disk usage patterns in order to
+       store them in a database for further treatment.

 "
 
 ###############################
 "
 
 ###############################

-section "disk space monitoring"
+section "Disk space monitoring"

 ###############################
 
 option "min-free-mb" m
 #~~~~~~~~~~~~~~~~~~~~~
 ###############################
 
 option "min-free-mb" m
 #~~~~~~~~~~~~~~~~~~~~~

-"minimal amount of free disk space"
+"Minimal amount of free disk space"

 int typestr="megabytes"
 default="100"
 optional
 details="
 int typestr="megabytes"
 default="100"
 optional
 details="

-       If less that this many megabytes of space is available on
-       the file system containing the destination directory, \"dss
-       --run\" will stop the currently running rsync process and will
-       start to remove snapshots, starting from the oldest snapshot,
-       until the free disk space exceeds this value.  See also the
-       --min_free_percent option.
+       If disk space on the file system containing the destination
+       directory gets low, \"dss --run\" will suspend the currently
+       running rsync process and will start to remove snapshots in
+       order to free disk space. This option specifies the minimal
+       amount of free disk space. If less than the given number of
+       megabytes is available, snapshots are being deleted. See also
+       the --min_free_percent and the min-free-percent-inodes options.

 
        A value of zero deactivates this check.
 
        A value of zero deactivates this check.

-

 "
 
 option "min-free-percent" p
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "
 
 option "min-free-percent" p
 #~~~~~~~~~~~~~~~~~~~~~~~~~~

-"minimal percent of free disk space"
+"Minimal percent of free disk space"

 int typestr="percent"
 default="2"
 optional
 details="
 int typestr="percent"
 default="2"
 optional
 details="

-       See --min_free.  Note that it is not recommended to set both
-       --min_fre_mb and --min_free_percent to zero as this will
+       See --min-free-mb. Note that it is not recommended to set both
+       --min-free-mb and --min-free-percent to zero as this will

        cause your file system to fill up quickly.
 "
        cause your file system to fill up quickly.
 "

+option "min-free-percent-inodes" i
+#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+"Minimal percent of free inodes"
+int typestr="percent"
+default="0"
+optional
+details="
+       Specify the minimum amount of free inodes on the file system
+       containing the destination dir. If less than that many inodes
+       are free, snatshot removal kicks in just as in case of low
+       disk space.
+
+       Note that not every file system supports the concept of inodes.
+       Moreover it is not possible to reliably detect whether this is
+       the case. Therefore this feature is disabled by default. It's
+       safe to enable it for ext3 file systems on linux though.
+
+       A value of zero (the default) deactivates this check.
+"