I agree, to the point. I have my RRAs defined with avg, min and max values and full resolution is not necessary for 2 whole weeks because of that. Minimum and maximum values get preserved and I can still see when spikes or dips have occured.
But you have to modify the frontend's graphing code to take advantage of such feature. b. PS: In the beginning I was very disappointed with gmetad's graphs, very low res, and shabby color in frontend (gray - yuck:) On 15 December 2010 17:49, Vladimir Vuksan <[email protected]> wrote: > > I was fortunate enough to receive a response from Tobi Oetiker clearing up > some of my misconceptions about RRD ie. you can read the response here > > http://vuksan.com/blog/2010/12/14/misconceptions-about-rrd-storage/#comment-7728 > > When you update an rrd file only the data which changed is written to the > rrd file (hence the circular buffers) ... due to the way hard diskts work, > a whole block has to be written for every write (which is ~4096 bytes) it > is still much less than the whole file ... run rrdtool with strace to see > for yourself. > > When using rrdcached, it will collect multiple updates before writing them > to disk. Theoretically you could see a performance improvement by a factor > of 512 since it would only write a single block 8 * 512 bytes for 512 > updates of one 8 Byte number. > > Based on this input I propose we change the default storage options for > Gmetad. Currently settings are as follows in gmetad/conf.c.in > > config->num_RRAs = 5; > config->RRAs[0] = "RRA:AVERAGE:0.5:1:244"; > config->RRAs[1] = "RRA:AVERAGE:0.5:24:244"; > config->RRAs[2] = "RRA:AVERAGE:0.5:168:244"; > config->RRAs[3] = "RRA:AVERAGE:0.5:672:244"; > config->RRAs[4] = "RRA:AVERAGE:0.5:5760:374"; > > I propose we change it to have full resolution for up to two weeks ie. > 244*24*14 = 81984 and have averages for 2 years ie. > > config->num_RRAs = 3; > config->RRAs[0] = "RRA:AVERAGE:0.5:1:81984"; > config->RRAs[3] = "RRA:AVERAGE:0.5:672:244"; > config->RRAs[4] = "RRA:AVERAGE:0.5:5760:748"; > > You can still override the settings in gmetad.conf but we should start > with higher defaults. > > Does this sound reasonable ? > > Vladimir > > ------------------------------------------------------------------------------ > Lotusphere 2011 > Register now for Lotusphere 2011 and learn how > to connect the dots, take your collaborative environment > to the next level, and enter the era of Social Business. > http://p.sf.net/sfu/lotusphere-d2d > _______________________________________________ > Ganglia-general mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/ganglia-general > ------------------------------------------------------------------------------ Lotusphere 2011 Register now for Lotusphere 2011 and learn how to connect the dots, take your collaborative environment to the next level, and enter the era of Social Business. http://p.sf.net/sfu/lotusphere-d2d _______________________________________________ Ganglia-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/ganglia-general
