X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=doc%2Frrdtutorial.pod;h=e29cd503c081fe1225831be49a3532a8d50e5ba7;hb=a57bc62667ff447309c0ed2d1a14aa387261bcfb;hp=d6ec09d25af097cbb13ff53f7019563c94f0183c;hpb=074e7a02198142cd0e270baae5dc4b42a942addb;p=rrdtool.git diff --git a/doc/rrdtutorial.pod b/doc/rrdtutorial.pod index d6ec09d..e29cd50 100644 --- a/doc/rrdtutorial.pod +++ b/doc/rrdtutorial.pod @@ -56,7 +56,7 @@ element. As we are on a circle there is neither a beginning nor an end, you can go on and on and on. After a while, all the available places will be used and the process automatically reuses old locations. This way, the dataset will not grow in size and therefore requires no maintenance. -RRDtool works with with Round Robin Databases (RRDs). It stores and retrieves +RRDtool works with Round Robin Databases (RRDs). It stores and retrieves data from them. =head2 What data can be put into an RRD? @@ -323,13 +323,18 @@ It should return the following output: 920808600: 6.6666666667e-03 920808900: 3.3333333333e-03 920809200: nan - -If it doesn't, something may be wrong. Perhaps your OS will print -"NaN" in a different form. "NaN" stands for "Not A Number". If your OS -writes "U" or "UNKN" or something similar that's okay. If something -else is wrong, it will probably be due to an error you made (assuming -that my tutorial is correct of course :-). In that case: delete the -database and try again. + 920809500: nan + +Note that you might get more rows than you expect. The reason for this is +that you ask for a time range that ends on 920809200. The number that is +written behind 920809200: in the list above covers the time range from +920808900 to 920809200, EXCLUDING 920809200. Hence to be on the sure side, +you receive the entry from 920809200 to 920809500 as well since it INCLUDES +920809200. You may also see "NaN" instead of "nan" this is OS dependent. +"NaN" stands for "Not A Number". If your OS writes "U" or "UNKN" or +something similar that's okay. If something else is wrong, it will probably +be due to an error you made (assuming that my tutorial is correct of course +:-). In that case: delete the database and try again. The meaning of the above output will become clear below.