[rrd-users] Re: RRDs::update slowness

[Tobias Oetiker]

Yesterday Chris Snell wrote:

 |
 | Hi All,
 |
 | I'm having a strange problem and I'm wondering if anyone else has run
 | into it.  I'm noticing a lot of slowness when updating an RRD file with
 | many DS'es under Solaris.  Updates are taking as long as 10 seconds on
 | this (unloaded) Enterprise 250 machine.  I've never had this problem
 | before but then again, I've never tried to use 17 DS's in one RRD file.
 |  Here's my rrdcreate call:
 |
 |         RRDs::create ("$rrd_file", "--step", "60", "--start",
 | "$one_month_ago",
 |         "DS:iorps:GAUGE:120:0:U",
 |         "DS:la5:GAUGE:120:0:U",
 |         "DS:nrks:GAUGE:120:0:U",
 |         "DS:nc:GAUGE:120:0:U",
 |         "DS:iowks:GAUGE:120:0:U",
 |         "DS:cpuu:GAUGE:120:0:U",
 |         "DS:cpuw:GAUGE:120:0:U",
 |         "DS:np:GAUGE:120:0:U",
 |         "DS:iowps:GAUGE:120:0:U",
 |         "DS:la15:GAUGE:120:0:U",
 |         "DS:nwks:GAUGE:120:0:U",
 |         "DS:iorks:GAUGE:120:0:U",
 |         "DS:cpui:GAUGE:120:0:U",
 |         "DS:cpuk:GAUGE:120:0:U",
 |         "DS:la1:GAUGE:120:0:U",
 |         "DS:fm:GAUGE:120:0:U",
 |         "DS:sr:GAUGE:120:0:U",
 |         "RRA:AVERAGE:0.5:1:3600",
 |         "RRA:AVERAGE:0.5:12:3600",
 |         "RRA:AVERAGE:0.5:60:7200",
 |         "RRA:MIN:0.5:1:3600",
 |         "RRA:MIN:0.5:12:3600",
 |         "RRA:MIN:0.5:60:7200",
 |         "RRA:MAX:0.5:1:3600",
 |         "RRA:MAX:0.5:12:3600",
 |         "RRA:MAX:0.5:60:7200");
 |         my $ERR=RRDs::error;
 |         print "ERROR while creating $rrd_file: $ERR\n" if $ERR;

Hi Chris,

If the rrd is created 'one month ago' but the update you run into
it is 'now' then rrdtool has to perform 30*24*60 updates to upgrade
the rrd file to the current time ... this takes some time ...

cheers
tobi
 |
 | While the call to RRDs::update is running, I see the following with
 | truss(1):
 |
 | lseek(4, 4244368, SEEK_SET)                     = 4244368
 | write(4, "7FFFFFFFFFFFFFFF7FFFFFFF".., 8192)    = 8192
 | write(4, "7FFFFFFFFFFFFFFF7FFFFFFF".., 8192)    = 8192
 | write(4, "7FFFFFFFFFFFFFFF7FFFFFFF".., 8192)    = 8192
 | write(4, "7FFFFFFFFFFFFFFF7FFFFFFF".., 8192)    = 8192
 | [ the write() call repeats about 100x before another lseek() call is
 | made ... ]
 |
 | Any ideas?
 |
 | thanks,
 |
 | Chris
 |
 |
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