From 52b2ca93729d41dc41b811493c560d63637c9d9f Mon Sep 17 00:00:00 2001 From: Andre Noll Date: Tue, 29 Dec 2015 15:52:32 +0000 Subject: [PATCH 1/1] 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. --- dss.ggo | 35 +++++++++++++++++++---------------- 1 file changed, 19 insertions(+), 16 deletions(-) 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" -- 2.39.2