[rrd-users] Time Zone problem

[Nelson test]

Hi,

I am in Hong Kong (UTC+8) and the time zone is CST displayed in Red Hat Linux.

It seems there is a problem with the database created if the interval is 1 day.

The database is good if interval is 5 minutes:

# rrdtool create test1.rrd -b 963417600 -s 300 DS:speed:GAUGE:130000:U:U 
RRA:LAST:0.5:1:10

The database is good as the last record is 7/13 00:00:00 CST:

<!-- Round Robin Database Dump -->
<rrd>
        <version> 0001 </version>
        <step> 300 </step> <!-- Seconds -->
        <lastupdate> 963417600 </lastupdate> <!-- 2000-07-13 00:00:00 CST -->

        <ds>
                <name> speed </name>
                <type> GAUGE </type>
                <minimal_heartbeat> 130000 </minimal_heartbeat>
                <min> NaN </min>
                <max> NaN </max>

                <!-- PDP Status -->
                <last_ds> UNKN </last_ds>
                <value> 0.0000000000e+00 </value>
                <unknown_sec> 0 </unknown_sec>
        </ds>

<!-- Round Robin Archives -->
        <rra>
                <cf> LAST </cf>
                <pdp_per_row> 1 </pdp_per_row> <!-- 300 seconds -->

                <cdp_prep>
                        <ds><value> NaN </value>  <unknown_datapoints> 0 </unkno
wn_datapoints></ds>
                </cdp_prep>
                <database>
                        <!-- 2000-07-12 23:15:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-12 23:20:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-12 23:25:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-12 23:30:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-12 23:35:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-12 23:40:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-12 23:45:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-12 23:50:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-12 23:55:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-13 00:00:00 CST --> <row><v> NaN </v></row>
                </database>
        </rra>
</rrd>


However, if the interval is 1 day (86400 seconds):

# rrdtool create test.rrd -b 963417600 -s 86400 DS:speed:GAUGE:130000:U:U 
RRA:LAST:0.5:1:10

As you can see, the last update time is good 7/13 00:00:00 but all records are 
08:00:00 CST !!! It seems it is saving data using 00:00:00 UTC time.

<!-- Round Robin Database Dump -->
<rrd>
        <version> 0001 </version>
        <step> 86400 </step> <!-- Seconds -->
        <lastupdate> 963417600 </lastupdate> <!-- 2000-07-13 00:00:00 CST -->

        <ds>
                <name> speed </name>
                <type> GAUGE </type>
                <minimal_heartbeat> 130000 </minimal_heartbeat>
                <min> NaN </min>
                <max> NaN </max>

                <!-- PDP Status -->
                <last_ds> UNKN </last_ds>
                <value> 0.0000000000e+00 </value>
                <unknown_sec> 57600 </unknown_sec>
        </ds>

<!-- Round Robin Archives -->
        <rra>
                <cf> LAST </cf>
                <pdp_per_row> 1 </pdp_per_row> <!-- 86400 seconds -->

                <cdp_prep>
                        <ds><value> NaN </value>  <unknown_datapoints> 0 </unkno
wn_datapoints></ds>
                </cdp_prep>
                <database>
                        <!-- 2000-07-03 08:00:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-04 08:00:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-05 08:00:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-06 08:00:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-07 08:00:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-08 08:00:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-09 08:00:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-10 08:00:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-11 08:00:00 CST --> <row><v> NaN </v></row>
                        <!-- 2000-07-12 08:00:00 CST --> <row><v> NaN </v></row>
                </database>
        </rra>
</rrd>


It is a problem as if I am updating data, values saved are recalculate.

e.g. previous value is 80 and now 60. But it will saved as 80 and 73.333.
This is because, while I am updating at 00:00:00 CST time but it is saving as 
08:00:00 CST time!

I have no problem with small intervals.

Thanks for any help

-nc

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