[rrd-users] Fetching from the beginning of an RRD file
travislspencer at gmail.com
Thu Mar 1 02:05:30 CET 2007
I am trying to fetch all data from the begging of an RRD file. I'm
not sure when the first entry was added to it, however, so I thought I
could just set the start time to zero. For example, something like
rrdtool fetch foo.rrd AVERAGE -s 0
That doesn't seem to work though. At first, I thought it was because
I was using an old version of rrdtool (1.0.49). I got a newer version
(1.2.10), but the unexpected behavior remained. Then, I discovered
that if I set the start time to something more recent than epoch, I
got non-NaN values.
To test things more systematically, I wrote a little script:
if [[ "$1" == "new" ]]; then
$R fetch $RRD_FILE AVERAGE -s $2 2>&1 | \
tail -n +3 | fgrep -v "#IND" | wc -l
echo "\tZero Start Time\t\tNon-Zero Start Time"
RESULT1=$(test_start_time old 0)
RESULT2=$(test_start_time old $START_TIME)
echo "Old RRD\t$RESULT1\t\t\t$RESULT2"
RESULT1=$(test_start_time new 0)
RESULT2=$(test_start_time new $START_TIME)
echo "New RRD\t$RESULT1\t\t\t$RESULT2"
Here is some sample output from that script:
Zero Start Time Non-Zero Start Time
Old RRD 0 20
New RRD 0 20
I don't understand this. Can RRD only cope with start times that are
more recent than some particular date? Can someone shed some light on
this for me?
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