rrdupdate - Store a new set of values into the RRD
rrdtool {update | updatev} filename [--template|-t ds-name[:ds-name]...] [--daemon address] [--] N|timestamp:value[:value...] at-timestamp@value[:value...] [timestamp:value[:value...] ...]
The update function feeds new data values into an RRD. The data is time aligned (interpolated) according to the properties of the RRD to which the data is written.
This alternate version of update takes the same arguments and performs the same function. The v stands for verbose, which describes the output returned. updatev returns a list of any and all consolidated data points (CDPs) written to disk as a result of the invocation of update. The values are indexed by timestamp (time_t), RRA (consolidation function and PDPs per CDP), and data source (name). Note that depending on the arguments of the current and previous call to update, the list may have no entries or a large number of entries.
Since updatev requires direct disk access, the --daemon option cannot be used with this command.
The name of the RRD you want to update.
By default, the update function expects its data input in the order the data sources are defined in the RRD, excluding any COMPUTE data sources (i.e. if the third data source DST is COMPUTE, the third input value will be mapped to the fourth data source in the RRD and so on). This is not very error resistant, a---!---!---!---!---!---!---!---!---!---> now shift 1 t0 <-----------------------> window <---------------> shift 2 <-----------------------------------------------> window <---------------> shift 1 t1 <-----------------------> window <---------------> shift 2 <-----------------------------------------------> window <--------------->
Value at sample (t0) will be the average between (t0-shift1-window) and (t0-shift1)
and between (t0-shift2-window) and (t0-shift2)
Value at sample (t1) will be the average between (t1-shift1-window) and (t1-shift1)
and between (t1-shift2-window) and (t1-shift2)
The function is by design NAN-safe. This also allows for extrapolation into the future (say a few days) - you may need to define the data series whit the optional start= parameter, so that the source data series has enough data to provide prediction also at the beginning of a graph...
Here an example, that will create a 10 day graph that also shows the prediction 3 days into the future with its uncertainty value (as defined by avg+-4*sigma) This also shows if the prediction is exceeded at a certain point.
rrdtool graph image.png --imgformat=PNG \ --start=-7days --end=+3days --width=1000 --height=200 --alt-autoscale-max \ DEF:value=value.rrd:value:AVERAGE:start=-14days \ LINE1:value#ff0000:value \ CDEF:predict=86400,-7,1800,value,PREDICT \ CDEF:sigma=86400,-7,1800,value,PREDICTSIGMA \ CDEF:upper=predict,sigma,3,*,+ \ CDEF:lower=predict,sigma,3,*,- \ LINE1:predict#00ff00:prediction \ LINE1:upper#0000ff:upper\ certainty\ limit \ LINE1:lower#0000ff:lower\ certainty\ limit \ CDEF:exceeds=value,UN,0,value,lower,upper,LIMIT,UN,IF \ TICK:exceeds#aa000080:1
Note: Experience has shown that a factor between 3 and 5 to scale sigma is a good discriminator to detect abnormal behavior. This obviously depends also on the type of data and how "noisy" the data series is.
This prediction can only be used for short term extrapolations - say a few days into the future-
UNKN
Pushes an unknown value on the stack
INF, NEGINF
Pushes a positive or negative infinite value on the stack. When such a value is graphed, it appears at the top or bottom of the graph, no matter what the actual value on the y-axis is.
PREV
Pushes an unknown value if this is the first value of a data set or otherwise the result of this CDEF at the previous time step. This allows you to do calculations across the data. This function cannot be used in VDEF instructions.
PREV(vname)
Pushes an unknown value if this is the first value of a data set or otherwise the result of the vname variable at the previous time step. This allows you to do calculations across the data. This function cannot be used in VDEF instructions.
COUNT
Pushes the number 1 if this is the first value of the data set, the number 2 if it is the second, and so on. This special value allows you to make calculations based on the position of the value within the data set. This function cannot be used in VDEF instructions.
Time inside RRDtool is measured in seconds since the epoch. The
epoch is defined to be Thu Jan 1 00:00:00 UTC 1970.
NOW
Pushes the current time on the stack.
TIME
Pushes the time the currently processed value was taken at onto the stack.
LTIME
Takes the time as defined by TIME, applies the time zone offset valid at that time including daylight saving time if your OS supports it, and pushes the result on the stack. There is an elaborate example in the examples section below on how to use this.
DUP, POP, EXC
Duplicate the top element, remove the top element, exchange the two top elements.
These operators work only on VDEF statements. Note that currently ONLY these work for VDEF.
Return the corresponding value, MAXIMUM and MINIMUM also return the first occurrence of that value in the time component.
Example: VDEF:avg=mydata,AVERAGE
Returns the standard deviation of the values.
Example: VDEF:stdev=mydata,STDEV