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1 #
2 package "dss"
3 version "0.0.1"
4 purpose "the dyadic snapshot scheduler"
5
6 text "
7 dss snapshot aging is implemented in terms of intervals. There are
8 two command line options related to intervals: the duration of a
9 'unit' interval and the number of those intervals.
10
11 dss removes any snapshots older than the given number of intervals
12 times the duration of an unit interval and tries to keep the following
13 amount of snapshots per interval:
14
15 interval number number of snapshots
16 ===============================================
17 0 2 ^ (num_intervals - 1)
18 1 2 ^ (num_intervals - 2)
19 2 2 ^ (num_intervals - 3)
20 ...
21 num_intervals - 2 2
22 num_intervals - 1 1
23 num_intervals 0
24
25 In other words, the oldest snapshot will at most be unit_interval *
26 num_intervala old (= 5 days * 4 = 20 days if default values are used).
27 Moreover, there are at most 2^num_intervals - 1 snapshots in total
28 (i.e. 31 by default). Observe that you have to create at least
29 num_intervals snapshots each interval for this to work out. "
30
31
32
33 option "config_file" c
34 #~~~~~~~~~~~~~~~~~~~~~
35 "(default='~/.dssrc')"
36
37 string typestr="filename"
38 optional
39
40 section "Logging"
41 #~~~~~~~~~~~~~~~~
42
43 option "loglevel" l
44 #~~~~~~~~~~~~~~~~~~
45
46 "set loglevel (0-6)"
47
48 int typestr="level"
49 default="4"
50 optional
51
52 defgroup "command"
53 groupdesc="
54 dss supports a couple of commands each of which corresponds to a different
55 command line option. Exactly one of these options must be given.
56 "
57 required
58
59 groupoption "create" C
60 #~~~~~~~~~~~~~~~~~~~~~
61 "create a new snapshot"
62 group="command"
63 details="
64 Execute the rsync command to create a new snapshot.Mote that this
65 command does not care about free disk space.
66 "
67 groupoption "prune" P
68 #~~~~~~~~~~~~~~~~~~~~
69 "remove a redundant snapshot"
70 group="command"
71 details="
72 A snapshot is considered redundant if it ether belongs to
73 an interval greater than the maximum nuber of intervals,
74 or if it belongs to an interval that already contains more
75 than the desired number of snapshots.
76 "
77
78 groupoption "ls" L
79 #~~~~~~~~~~~~~~~~~
80 "print a list of all snapshots"
81 group="command"
82 details="
83 The list will contain all snapshots not matter of their state,
84 i.e. incomplete snapshots and snapshots being deleted will
85 also be listed.
86 "
87
88 groupoption "run" R
89 #~~~~~~~~~~~~~~~~~~
90 "start creating and pruning snapshots"
91 group="command"
92 details="
93 This is the main mode of operation. Snapshots will be created
94 as needed and pruned automatically.
95 "
96
97 option "logfile" -
98 #~~~~~~~~~~~~~~~~~
99
100 "logfile for the dss daemon process"
101
102 string typestr="filename"
103 optional
104
105 section "rsync-related options"
106 #==============================
107
108 option "remote_user" U
109 #~~~~~~~~~~~~~~~~~~~~~
110
111 "remote user name (default: current user)"
112
113 string typestr="username"
114 optional
115
116 option "remote_host" H
117 #~~~~~~~~~~~~~~~~~~~~~
118
119 "remote host"
120
121 string typestr="hostname"
122 default="localhost"
123 optional
124
125 option "source_dir" S
126 #~~~~~~~~~~~~~~~~~~~~
127
128 "directory to backup on the remote host"
129
130 string typestr="dirname"
131 optional
132
133 option "dest_dir" D
134 #~~~~~~~~~~~~~~~~~~
135
136 "snapshots dir on the local host"
137
138 string typestr="dirname"
139 optional
140
141 option "rsync_option" O
142 #~~~~~~~~~~~~~~~~~~~~~~
143
144 "further rsync options that are passed
145 verbatim to the rsync command."
146
147 string typestr="option"
148 optional
149 multiple
150
151
152 option "exclude_patterns" e
153 #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
154
155 "rsync exclude patterns"
156
157 string typestr="path"
158 optional
159
160
161 section "Intervals"
162 #~~~~~~~~~~~~~~~~~~
163
164
165 option "unit_interval" u
166 #~~~~~~~~~~~~~~~~~~~~~~~
167 "the duration of a unit interval"
168
169 int typestr="days"
170 default="4"
171 optional
172
173 option "num_intervals" n
174 #~~~~~~~~~~~~~~~~~~~~~~~
175 "the number of unit intervals"
176
177 int typestr="num"
178 default="5"
179 optional
180
181 section "Hooks"
182 #==============
183
184 option "pre_create_hook" r
185 #~~~~~~~~~~~~~~~~~~~~~~~~~~
186 "Executed before snapshot creation"
187
188 string typestr="command"
189 default="/bin/true"
190 optional
191
192 details="
193 Execute this command before trying to create a new snapshot
194 If this command returns with a non-zero exit status, do not
195 perform the backup. One possible application of this is to
196 return non-zero during office hours in order to not slow down
197 the file systems by taking snapshots.
198 "
199
200
201 option "post_create_hook" o
202 #~~~~~~~~~~~~~~~~~~~~~~~~~~
203 "Executed after snapshot creation"
204
205 string typestr="command"
206 default="/bin/true"
207 optional
208
209 details="
210 Execute this after a snapshot has successfully been created
211 The return value on the command is ignored. For instance one
212 could count the number of files per user and/or the disk
213 usage patterns in order to store them in a database for
214 further treatment.
215 "
216 option "creation_sleep" s
217 #~~~~~~~~~~~~~~~~~~~~~~~~
218 "sleep interval"
219
220 int typestr="minutes"
221 default="60"
222 optional
223
224 details="
225 The sleep interval for snapshot creation in minutes.
226 The daemon will, in an endlees loop, create a snapshot and
227 then sleep that many minutes.
228 "
229
230
231 option "min_free" m
232 #~~~~~~~~~~~~~~~~~~
233
234 "minimal amount of free space"
235
236 int typestr="gigabytes"
237 default="50"
238 optional
239
240 details="
241 If less that this many gigabytes of space is available,
242 dss will start to remove snapshots (starting from the oldest
243 snapshot) until the free disk space exeecds this value.
244 "