Question: How can I fetch the finest resolution while specifying e-2days for the start time?
I am rather new to working with RRDs and would like some assistance with using the fetch command to fetch data for the finest resolution. In referring to the fetch documentation, I noticed that the finest resolution should be the default. However, I have noticed (see RRD Information below) that the rra with a pdp_per_row of 168 is being accessed when a start time of e-2days is used. This results in (168 * 15) / 60 = 42 minutes. If the start time is not specified, then the rra with a pdp_per_row of 24 is being accessed. This results in (24 * 15) / 60 = 6 minutes. What I really want is to access the rra with a pdp_per_row of 1. I discovered that if I specify the start time as e-1hour, then the rra with a pdp_per_row of 1 is accessed. The question is how to access this rra with the start time of e-2days. I tried to follow the fetch documentation for Resolution Interval using Perl like this without success: PERL Code: use File::Spec; $rrdres = 1; open(STDERR, '> ' . File::Spec->devnull); $ctime = time; $file = '/data/rrd_data/cpu_speed.rrd'; my($cmd) = " \"/usr/bin/rrdtool\" fetch \"$file\" AVERAGE -r $rrdres -e @{[int($ctime/$rrdres)*$rrdres]} -s e-2days |"; open(RRD, $cmd) or die "Unable to run rrdtool command:\n $cmd\n"; my(@values) = <RRD>; chomp @values; print "RRDFILE=$file \n \n"; print "Command=$cmd \n \n"; print "CF= \n"; for my $instance (@values) { print "$instance \n"; } RRD Information (partial): rrd_version = "0003" step = 15 last_update = 1342112399 ds[sum].type = "GAUGE" ds[sum].minimal_heartbeat = 120 ds[sum].min = NaN ds[sum].max = NaN ds[sum].last_ds = "2.85" ds[sum].value = 3.9900000000e+01 ds[sum].unknown_sec = 0 rra[0].cf = "AVERAGE" rra[0].rows = 244 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 rra[1].cf = "AVERAGE" rra[1].rows = 244 rra[1].pdp_per_row = 24 rra[1].xff = 5.0000000000e-01 rra[1].cdp_prep[0].value = 6.8923333333e+01 rra[1].cdp_prep[0].unknown_datapoints = 0 rra[2].cf = "AVERAGE" rra[2].rows = 244 rra[2].pdp_per_row = 168 rra[2].xff = 5.0000000000e-01 rra[2].cdp_prep[0].value = 1.3681000000e+02 rra[2].cdp_prep[0].unknown_datapoints = 0 Output from generated fetch command: /usr/bin/rrdtool" fetch "/data/rrd_data/cpu_speed.rrd" AVERAGE -r 1 -e 1342114745 -s e-2days 1341942840: 2.5270000000e+03 1341945360: 2.5270000000e+03 1341947880: 2.5270000000e+03 1341950400: 2.5270000000e+03 1341952920: 2.5270000000e+03 1341955440: 2.5270000000e+03 1341957960: 2.5270000000e+03 1341960480: 2.5270000000e+03 1341963000: 2.5270000000e+03 1341965520: 2.5270000000e+03 1341968040: 2.5270000000e+03 1341970560: 2.5270000000e+03 1341973080: 2.5270000000e+03 1341975600: 2.5270000000e+03 1341978120: 2.5270000000e+03 1341980640: 2.5270000000e+03 1341983160: 2.5270000000e+03 1341985680: 2.5270000000e+03 1341988200: 2.5270000000e+03 1341990720: 2.5270000000e+03 1341993240: 2.5270000000e+03 1341995760: 2.5270000000e+03 1341998280: 2.5270000000e+03 1342000800: 2.5270000000e+03 1342003320: 2.5270000000e+03 1342005840: 2.5270000000e+03 1342008360: 2.5270000000e+03 1342010880: 2.5270000000e+03 1342013400: 2.5270000000e+03 1342015920: 2.5270000000e+03 1342018440: 2.5270000000e+03 1342020960: 2.5270000000e+03 1342023480: 2.5270000000e+03 1342026000: 2.5270000000e+03 1342028520: 2.5270000000e+03 1342031040: 2.5270000000e+03 1342033560: 2.5270000000e+03 1342036080: 2.5270000000e+03 1342038600: 2.5270000000e+03 1342041120: 2.5270000000e+03 1342043640: 2.5270000000e+03 1342046160: 2.5270000000e+03 1342048680: 2.5270000000e+03 1342051200: 2.5270000000e+03 1342053720: 2.5270000000e+03 1342056240: 2.5270000000e+03 1342058760: 2.5270000000e+03 1342061280: 2.5270000000e+03 1342063800: 2.5270000000e+03 1342066320: 2.5270000000e+03 1342068840: 2.5270000000e+03 1342071360: 2.5270000000e+03 1342073880: 2.5270000000e+03 1342076400: 2.5270000000e+03 1342078920: 2.5270000000e+03 1342081440: 2.5270000000e+03 1342083960: 2.5270000000e+03 1342086480: 2.5270000000e+03 1342089000: 2.5270000000e+03 1342091520: 2.5270000000e+03 1342094040: 2.5270000000e+03 1342096560: 2.5270000000e+03 1342099080: 2.5270000000e+03 1342101600: 2.5270000000e+03 1342104120: 2.5270000000e+03 1342106640: 2.5270000000e+03 1342109160: 2.5270000000e+03 1342111680: 2.5270000000e+03 1342114200: 2.5270000000e+03 1342116720: nan -- Thanks, Jim
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