On Mon, Feb 10, 2003 at 12:39:51PM -0800, John Giordano wrote: > > no beginning and no end. within is contained the knowledge we seek.
true, provided you also have a clue about the pointer to "now". > what I am not sure on is what I have heard on how RRD "compresses" the data > over time. What does this mean? It doesn't compress data. It does however do the following: inputs: A, B, C, D, E, F, G, H, I, J, K, L ... archives: p,q,r ... in archive p, each individual input is stored in archive q, the average of two inputs is stored in archive r, the average of four inputs is stored A --> p B --> p >and< avg(A,B) --> q C --> p D --> p >and< avg(C,D) --> q >and< avg(A,B,C,D) --> r E --> p F --> p >and< avg(E,F) --> q G --> p H --> p >and< avg(G,H) --> q >and< avg(E,F,G,H) --> r ...and so on... > I understand that the .RRD logs don't grow and this is one of the many things > that are cool about RRD and the fact it only generates the graphs when need > be. If you need to graph one day per pixel (say for a yearly graph), it is nice to have the data available >>>in that resolution<<<. You don't want to spend time on computing the average of (86400/300) samples for each pixel at graph time. RRDtool will do this averaging (when instructed!) at storage. Also, if you never need to graph the data of last year's January in a high resolution image, why keep that data ? What this means is that it usually is a good thing to have, for instance: about 600 lines of 300 seconds per bucket about 600 lines of 30 minutes per bucket about 600 lines of 2 hours per bucket about 600 lines of 1 day per bucket This doesn't allow you to fetch data in a 300-second-per-bucket resolution from more than (300*600) seconds ago. It does allow you to get the same average in a lower resolution. If you want to know more, there's detailed documentation available. -- Much of what looks like rudeness in hacker circles is not intended to give offence. Rather, it's the product of the direct, cut-through-the-bullshit communications style that is natural to people who are more concerned about solving problems than making others feel warm and fuzzy. http://www.tuxedo.org/~esr/faqs/smart-questions.html -- Unsubscribe mailto:[EMAIL PROTECTED] Help mailto:[EMAIL PROTECTED] Archive http://www.ee.ethz.ch/~slist/rrd-users WebAdmin http://www.ee.ethz.ch/~slist/lsg2.cgi
