X-Git-Url: http://git.tuebingen.mpg.de/?p=dss.git;a=blobdiff_plain;f=dss.ggo;h=3133d037dc4f8a6ed5f035bd180e29b8d32597ad;hp=15c15a48ad7d9e69536e1be5e28260a031afe1d4;hb=442d1920cb866fb6e0a816d7e175b5cdb8c0e1a8;hpb=cf071bc345919c98c3c0e8737d731bd95411bd67 diff --git a/dss.ggo b/dss.ggo index 15c15a4..3133d03 100644 --- a/dss.ggo +++ b/dss.ggo @@ -1,6 +1,9 @@ +# Copyright (C) 2008 Andre Noll # +# Licensed under the GPL v2. For licencing details see COPYING. + package "dss" -version "0.0.3" +version "0.1.2" purpose "the dyadic snapshot scheduler dss creates hardlink-based snapshots of a given directory on a remote @@ -79,12 +82,17 @@ details=" is also given. " +################## +section "Commands" +################## + 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. + " required @@ -99,13 +107,14 @@ details=" groupoption "prune" P #~~~~~~~~~~~~~~~~~~~~ -"Remove a redundant snapshot" +"Remove redundant and outdated snapshots" group="command" details=" - A snapshot is considered redundant if it ether belongs to - an interval greater than the maximum number of intervals, -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 + A snapshot is considered outdated if it belongs to an interval + greater than the maximum number of intervals. It is said to be + redundant if it belongs to an interval that already contains + more than the desired number of snapshots. This command gets + rid of such snapshots. " groupoption "ls" L @@ -124,7 +133,9 @@ 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. " ############################### @@ -184,15 +195,13 @@ 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: -option "exclude-patterns" e -#~~~~~~~~~~~~~~~~~~~~~~~~~~ -"Rsync exclude patterns" -string typestr="path" -optional + --rsync-option --exclude --rsync-option /proc +" ################### section "Intervals" @@ -211,13 +220,14 @@ 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. " @@ -258,13 +268,62 @@ string typestr="command" optional details=" 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. + created. The full path of the newly created snapshot is + passed to the hook as the first argument. The exit code of + this 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. + 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. " ############################### @@ -304,13 +363,32 @@ option "min-free-percent-inodes" i #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "Minimal percent of free inodes" int typestr="percent" -default="2" +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 + are free, snapshot removal kicks in just as in case of low disk space. - A value of zero deactivates this check. + 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. +" + +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. "