X-Git-Url: http://git.tuebingen.mpg.de/?p=dss.git;a=blobdiff_plain;f=dss.ggo;h=506fbf105433fed61631ad965e5b8295068cbfe7;hp=a6644ee3954222db0ed21a568e0ce8e0717e7763;hb=1e77c93a4da4dae8b75fcd305552e56ccae89b90;hpb=20afe2a3b5467c42610a5587ad6914c035930fc8 diff --git a/dss.ggo b/dss.ggo index a6644ee..506fbf1 100644 --- a/dss.ggo +++ b/dss.ggo @@ -1,9 +1,9 @@ -# Copyright (C) 2008 Andre Noll +# Copyright (C) 2008-2009 Andre Noll # # Licensed under the GPL v2. For licencing details see COPYING. package "dss" -version "0.0.5" +version "0.1.3" purpose "the dyadic snapshot scheduler dss creates hardlink-based snapshots of a given directory on a remote @@ -107,13 +107,20 @@ details=" groupoption "prune" P #~~~~~~~~~~~~~~~~~~~~ -"Remove a redundant snapshot" +"Remove redundant and outdated snapshots" group="command" details=" - A snapshot is considered redundant if it ether belongs to - an interval greater than the maximum number of intervals, - or if it belongs to an interval that already contains more - than the desired number of snapshots. + A snapshot is considered outdated if its interval number + is greater or equal than the specified number of unit + intervals. See the \"Intervals\" section below for the precise + definition of these terms. + + A snapshot is said to be redundant if it belongs to an + interval that already contains more than the desired number + of snapshots. + + The prune command gets rid of both outdated and redundant + snapshots. " groupoption "ls" L @@ -132,7 +139,9 @@ groupoption "run" R group="command" details=" This is the main mode of operation. Snapshots will be created - as needed and pruned automatically. + in an endless loop as needed and pruned automatically. The loop + only terminates on fatal errors or if a terminating signal was + received. See also the --exit-hook option. " ############################### @@ -192,8 +201,12 @@ string typestr="option" optional multiple details=" - These option may be given multiple times. The arguments passed - to that option are passed verbatim to the rsync command. + This option may be given multiple times. The given argument is + passed verbatim to the rsync command. Note that in order to use + rsync options that require an argument, you have to specify the + option and its argument as separate --rsync-options, like this: + + --rsync-option --exclude --rsync-option /proc " ################### @@ -213,13 +226,14 @@ details=" 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. + keep 2^(n - 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 + 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. " @@ -269,6 +283,55 @@ details=" store them in a database for further analysis. " +option "pre-remove-hook" - +#~~~~~~~~~~~~~~~~~~~~~~~~~~ +"Executed before snapshot removal" +string typestr="command" +optional +details=" + Execute this command before removing a snapshot. The full + path to the snapshot about to be deleted is passed to the + command as the first argument. If the command returns with + a non-zero exit status, no snapshot is being removed and the + operation is retried later. + + For example, one might want to execute a script that checks + whether the snapshot to be deleted is currently used by + another process, e.g. by a tape-based backup system that runs + concurrently to dss. + + Another possible application of this is to record disk-usage + patterns before and after snapshot removal. +" + +option "post-remove-hook" - +#~~~~~~~~~~~~~~~~~~~~~~~~~~ +"Executed after snapshot removal" +string typestr="command" +optional +details=" + Execute this after a snapshot has successfully been removed. As + for the pre-remove hook, the full path of the removed snapshot + is passed to the hook as the first argument. The exit code + of this hook is ignored. +" + +option "exit-hook" e +#~~~~~~~~~~~~~~~~~~~ +"Executed if run command exits" +string typestr="command" +optional +details=" + This hook is only used if the --run command was given which + instructs dss to run in an endless loop. The exit-hook gets + executed whenever this endless loop terminates. The reason + for terminating the loop is passed as the first argument. + + One possible application for this hook is to send email to the + system administrator to let her know that no more snapshots + are going to be created. +" + ############################### section "Disk space monitoring" ############################### @@ -321,3 +384,17 @@ details=" A value of zero (the default) deactivates this check. " + +option "keep-redundant" k +#~~~~~~~~~~~~~~~~~~~~~~~~ +"Prune by disk space only" +flag off +details=" + If this flag is not given dss removes redundant and outdated + snapshots automatically. + + Otherwise, this feature is deactivated so that snapshots are + only being removed in case disk space or number of free inodes + becomes low. Use this flag if the file system containing the + destination directory is used for snapshots only. +"