[rrd-users] New User Question RRD not updating

[Stephen Green]

Hi,
Currently I'm trying to determine why an RRD will not update
First, I use the following command.
rrdtool create pressure.rrd --step 3600 DS:pres:GAUGE:300:U:U RRA:MIN:0.5:12:300 RRA:AVERAGE:0.5:12:300
The update will take place every hour.

In testing I tried updating the database with the following command
rrdtool update pressure.rrd N:860

The update appears to complete without error.

When I run the following command, the dataset seems to be empty.

rrdtool fetch pressure.rrd MIN  
                     pres

1068379200: nan
1068422400: nan
1068465600: nan
1068508800: nan
rrdtool fetch pressure.rrd AVERAGE
                     pres

1068379200: nan
1068422400: nan
1068465600: nan
1068508800: nan

Can somone explain why I'm unable to update the RRD ds.

Here is the rrdtool info if that helps.

[root at jsg1 Weather]# rrdtool info pressure.rrd
filename = "pressure.rrd"
rrd_version = "0001"
step = 3600
last_update = 1068497838
ds[pres].type = "GAUGE"
ds[pres].minimal_heartbeat = 300
ds[pres].min = NaN
ds[pres].max = NaN
ds[pres].last_ds = "UNKN"
ds[pres].value = 2.5870000000e+04
ds[pres].unknown_sec = 3408
rra[0].cf = "MIN"
rra[0].rows = 300
rra[0].pdp_per_row = 12
rra[0].xff = 5.0000000000e-01
rra[0].cdp_prep[0].value = NaN
rra[0].cdp_prep[0].unknown_datapoints = 8
rra[1].cf = "AVERAGE"
rra[1].rows = 300
rra[1].pdp_per_row = 12
rra[1].xff = 5.0000000000e-01
rra[1].cdp_prep[0].value = NaN
rra[1].cdp_prep[0].unknown_datapoints = 8
--
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