[rrd-users] Newbie -- Trouble adding 2 values to RRD DB

[Neil Saunders]

Hi All,

I'm getting to grips with RRD tool for the first time, but I'm running in to
problems getting even a simple example working.

The problem:

I have a historical set of data (bytes received per minute) that I wish to
"preload" in to an RRDB
before providing regular (per minute) updates going forward. I'm using
rrdtool 1.2.15 on Cygwin. My datasource has
periodic gaps - I'm presuming these gaps will automatically be marked as
unknown.

C:/cygwin/bin/rrdtool.exe create
c:/logmunge.dbt.pacs.com/rrd_db/RC1DBWF01.rrd --start 1199967600 --step 60
DS:bytes:ABSOLUTE:600:U:U RRA:LAST:0.5:1:600

How I interpret this: "Create a new RRD database storing times from Thu, 10
Jan 2008 12:20:00 GMT.
Records are added every 60 seconds. There is a single datasource called
"bytes", consisting of a ABSOLUTE datasource,
that is each record is counted from 0, and is not dependant on the last. If
no data is received in 600 seconds, mark it as "unknown".
Create 1 round robin archive, consisting of the LAST value (As we guarantee
only a single update in a minute), and xff of 0.5, and with PDP
calculated from a single update. Store 600 rows (10hr 1min)."

(RRD File Created)

Add a single record:

C:/cygwin/bin/rrdtool.exe updatev
c:/logmunge.dbt.pacs.com/www/../rrd_db/RC1DBWF01.rrd -t bytes
"1199967601:1432694"

$ rrdtool.exe info ../rrd_db/RC1DBWF01.rrd
filename = "../rrd_db/RC1DBWF01.rrd"
rrd_version = "0003"
step = 60
last_update = 1199967601
ds[bytes].type = "ABSOLUTE"
ds[bytes].minimal_heartbeat = 600
ds[bytes].min = NaN
ds[bytes].max = NaN
ds[bytes].last_ds = "UNKN"
ds[bytes].value = 1.4326940000e+06  <<< VALUE ADDED
ds[bytes].unknown_sec = 0
rra[0].cf = "LAST"
rra[0].rows = 600
rra[0].pdp_per_row = 1
rra[0].xff = 5.0000000000e-01
rra[0].cdp_prep[0].value = NaN
rra[0].cdp_prep[0].unknown_datapoints = 0

Immediately add another record for 23 minutes later:

C:/cygwin/bin/rrdtool.exe update
c:/logmunge.dbt.pacs.com/www/../rrd_db/RC1DBWF01.rrd -t bytes
"1199968981:5990214"

$ rrdtool.exe info ../rrd_db/RC1DBWF01.rrd
filename = "../rrd_db/RC1DBWF01.rrd"
rrd_version = "0003"
step = 60
last_update = 1199968981
ds[bytes].type = "ABSOLUTE"
ds[bytes].minimal_heartbeat = 600
ds[bytes].min = NaN
ds[bytes].max = NaN
ds[bytes].last_ds = "UNKN"
ds[bytes].value = NaN  <<< Why is this NaN???
ds[bytes].unknown_sec = 1
rra[0].cf = "AVERAGE"
rra[0].rows = 600
rra[0].pdp_per_row = 1
rra[0].xff = 5.0000000000e-01
rra[0].cdp_prep[0].value = NaN
rra[0].cdp_prep[0].unknown_datapoints = 0

Why is this value marked as unknown? I'm itching to generate a graph but
don't seem to be able to get my head around the basics - What am I missing?

Any help gratefully received!

Kind Regards,

Neil Saunders.
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