dss.ggo: Disable inode monitoring by default.

[dss.git] / dss.ggo

diff --git a/dss.ggo b/dss.ggo
index 295e9ed18bd9347a91cf86f1f277b69c696452cc..5c3783774420c9297e3d970a3f61adf434ddd791 100644 (file)
--- a/dss.ggo
+++ b/dss.ggo
@@ -1,6 +1,6 @@
 #
 package "dss"
 #
 package "dss"

-version "0.0.3"
+version "0.0.4"

 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


@@ -21,6 +21,14 @@ 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


@@ -30,8 +38,11 @@ flag off
 dependon="logfile"
 details="
        Note that dss refuses to start in daemon mode if no logfile
 dependon="logfile"
 details="
        Note that dss refuses to start in daemon mode if no logfile

-       was specified. This option makes sense only in conjuction
+       was specified. This option is mostly useful in conjuction

        with the -R option described below.
        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


@@ -55,7 +66,7 @@ int typestr="level"
 default="3"
 optional
 details="
 default="3"
 optional
 details="

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

 "
 
 option "logfile" -
 "
 
 option "logfile" -


@@ -71,8 +82,9 @@ 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
 
 "
 required
 


@@ -81,9 +93,10 @@ groupoption "create" C
 "Create a new snapshot"
 group="command"
 details="
 "Create a new snapshot"
 group="command"
 details="

-       Execute the rsync command to create a new snapshot. Note 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
 #~~~~~~~~~~~~~~~~~~~~
 "Remove a redundant snapshot"
 groupoption "prune" P
 #~~~~~~~~~~~~~~~~~~~~
 "Remove a redundant snapshot"


@@ -146,7 +159,7 @@ option "source-dir" -
 #~~~~~~~~~~~~~~~~~~~~
 "The data directory"
 string typestr="dirname"
 #~~~~~~~~~~~~~~~~~~~~
 "The data directory"
 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


@@ -157,7 +170,7 @@ option "dest-dir" -
 #~~~~~~~~~~~~~~~~~~
 "Snapshot dir"
 string typestr="dirname"
 #~~~~~~~~~~~~~~~~~~
 "Snapshot dir"
 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


@@ -192,29 +205,21 @@ int typestr="days"
 default="4"
 optional
 details="
 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 a 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


@@ -232,29 +237,34 @@ 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.

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


@@ -268,15 +278,15 @@ int typestr="megabytes"
 default="100"
 optional
 details="
 default="100"
 optional
 details="

-       If less than this many megabytes of space is available on
-       the file system containing the destination directory, \"dss
-       --run\" will suspend 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


@@ -286,7 +296,26 @@ int typestr="percent"
 default="2"
 optional
 details="
 default="2"
 optional
 details="

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