[rrd-users] can't update rrd with data.

[John Stile]

I need help to understand why my rrd won't accept data from my updates.

This is to chart a number once a day.

At the end of my backup script, if the rrd does not exist, it is created
via the following:

  rrdtool \
    create \
    "${RRD_File}" \
    --step 86400 \
    "DS:size:GAUGE:87000:U:U" \
    "RRA:LAST:0.5:1:365" \
    "RRA:LAST:0.5:30:60"

which I understand to mean the following:
 Create an rrd database, 
 with a PDP (primary data point) every 86400 seconds (24 hours),
 with a Data Store named='size', 
 of type type=GUAGE, 
 and if it isn't updated every  87000 seconds (a little over 24 hours), 
 the recorded value will be 'unknown' (this is the heartbeat).
 Only half the members of each RRA need to be present, or value will be 'unknown'.
 The first RRA uses 1 PDP and stores 365 records (for a 1 year period tracked).
The second RRA uses 30 PDP and stores 60 records (for a 5 year period tracked).

After this step, I try to add the size of the backup with the following
command:
  rrdtool update "${RRD_File}" "N:${size}"

The script log shows that the two variables ${RRD_File} and ${size} are
populated with the correct data.

I set the heartbeat to 87000 seconds (slightly higher than the step of
86400 seconds) to allow extra time for the backup to complete.

After the update, when I do a dump, nothing is stored in either rra.