From: Andre Noll <maan@tuebingen.mpg.de>
Date: Tue, 29 Dec 2015 15:52:32 +0000 (+0000)
Subject: Improve documentation of interval-related args.
X-Git-Tag: v0.1.7~22
X-Git-Url: http://git.tuebingen.mpg.de/?p=dss.git;a=commitdiff_plain;h=52b2ca93729d41dc41b811493c560d63637c9d9f;hp=05e75054398c9d39f62f8c4b9be7b874a2019a3c

Improve documentation of interval-related args.

Minor rewording of the help text for the --unit-interval option and
a new sentence which explains that the total number of snapshots
doubles if --num-intervals is increased by one.
---

diff --git a/dss.ggo b/dss.ggo
index 68b7a7a..8a3d304 100644
--- a/dss.ggo
+++ b/dss.ggo
@@ -275,22 +275,21 @@ 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 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^(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
-	each interval for this to work out because that is the number
-	of snapshots in interval zero.
+	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 of unit intervals, denoted n below.
+
+	dss removes snapshots older than n times u and tries to keep 2^(n -
+	k - 1) snapshots in interval k, where the interval number k counts
+	from zero to n - 1, with zero being the most recent unit interval.
+
+	Hence the oldest snapshot will at most be u * n days old (4 days *
+	5 intervals = 20 days, if default values are used). Moreover, there
+	are at most 2^n - 1 snapshots in total (2^5 - 1 = 31 by default). Note
+	that for this to work out your system must be fast enough to create at
+	least 2^(n - 1) snapshots per unit interval (16 snapshots in 4 days =
+	one snapshot in 6 hours), because this is the number of snapshots in
+	interval zero.
 "
 
 option "num-intervals" n
@@ -299,6 +298,10 @@ option "num-intervals" n
 int typestr="num"
 default="5"
 optional
+details="
+	Note that increasing this number by one doubles the total number of
+	snapshots. See the documentation of --unit-interval above.
+"
 
 ###############
 section "Hooks"