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diff --git a/doc/rrdcreate.txt b/doc/rrdcreate.txt
index eaa70c156b29c7826bfb9f998fbbac1678072e31..197959d5335442217aa8d2cc56ec6582bbc41ff0 100644 (file)
--- a/doc/rrdcreate.txt
+++ b/doc/rrdcreate.txt
with _\b*_\bU_\bN_\bK_\bN_\bO_\bW_\bN_\b* data.
_\bf_\bi_\bl_\be_\bn_\ba_\bm_\be
- The name of the R\bRR\bRD\bD you want to create. R\bRR\bRD\bD files should end with
- the extension _\b._\br_\br_\bd. However, R\bRR\bRD\bDt\bto\boo\bol\bl will accept any filename.
+ The name of the R\bRR\bRD\bD you want to create. R\bRR\bRD\bD files should end
+ with the extension _\b._\br_\br_\bd. However, R\bRR\bRD\bDt\bto\boo\bol\bl will accept any file-
+ name.
-\b--\b-s\bst\bta\bar\brt\bt|-\b-b\bb _\bs_\bt_\ba_\br_\bt _\bt_\bi_\bm_\be (default: now - 10s)
- Specifies the time in seconds since 1970-01-01 UTC when the first
- value should be added to the R\bRR\bRD\bD. R\bRR\bRD\bDt\bto\boo\bol\bl will not accept any data
- timed before or at the time specified.
+ Specifies the time in seconds since 1970-01-01 UTC when the
+ first value should be added to the R\bRR\bRD\bD. R\bRR\bRD\bDt\bto\boo\bol\bl will not accept
+ any data timed before or at the time specified.
- See also AT-STYLE TIME SPECIFICATION section in the _\br_\br_\bd_\bf_\be_\bt_\bc_\bh docu-
- mentation for other ways to specify time.
+ See also AT-STYLE TIME SPECIFICATION section in the _\br_\br_\bd_\bf_\be_\bt_\bc_\bh
+ documentation for other ways to specify time.
-\b--\b-s\bst\bte\bep\bp|-\b-s\bs _\bs_\bt_\be_\bp (default: 300 seconds)
- Specifies the base interval in seconds with which data will be fed
- into the R\bRR\bRD\bD.
+ Specifies the base interval in seconds with which data will be
+ fed into the R\bRR\bRD\bD.
D\bDS\bS:\b:_\bd_\bs_\b-_\bn_\ba_\bm_\be:\b:_\bD_\bS_\bT:\b:_\bd_\bs_\bt _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs
- A single R\bRR\bRD\bD can accept input from several data sources (D\bDS\bS), for
- example incoming and outgoing traffic on a specific communication
- line. With the D\bDS\bS configuration option you must define some basic
- properties of each data source you want to store in the R\bRR\bRD\bD.
-
- _\bd_\bs_\b-_\bn_\ba_\bm_\be is the name you will use to reference this particular data
- source from an R\bRR\bRD\bD. A _\bd_\bs_\b-_\bn_\ba_\bm_\be must be 1 to 19 characters long in
- the characters [a-zA-Z0-9_].
-
- _\bD_\bS_\bT defines the Data Source Type. The remaining arguments of a data
- source entry depend on the data source type. For GAUGE, COUNTER,
- DERIVE, and ABSOLUTE the format for a data source entry is:
-
- D\bDS\bS:\b:_\bd_\bs_\b-_\bn_\ba_\bm_\be:\b:_\bG_\bA_\bU_\bG_\bE _\b| _\bC_\bO_\bU_\bN_\bT_\bE_\bR _\b| _\bD_\bE_\bR_\bI_\bV_\bE _\b| _\bA_\bB_\bS_\bO_\bL_\bU_\bT_\bE:\b:_\bh_\be_\ba_\br_\bt_\bb_\be_\ba_\bt:\b:_\bm_\bi_\bn:\b:_\bm_\ba_\bx
-
- For COMPUTE data sources, the format is:
-
- D\bDS\bS:\b:_\bd_\bs_\b-_\bn_\ba_\bm_\be:\b:_\bC_\bO_\bM_\bP_\bU_\bT_\bE:\b:_\br_\bp_\bn_\b-_\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn
-
- In order to decide which data source type to use, review the defi-
- nitions that follow. Also consult the section on "HOW TO MEASURE"
- for further insight.
-
- G\bGA\bAU\bUG\bGE\bE
- is for things like temperatures or number of people in a room
- or the value of a RedHat share.
-
- C\bCO\bOU\bUN\bNT\bTE\bER\bR
- is for continuous incrementing counters like the ifInOctets
- counter in a router. The C\bCO\bOU\bUN\bNT\bTE\bER\bR data source assumes that the
- counter never decreases, except when a counter overflows. The
- update function takes the overflow into account. The counter
- is stored as a per-second rate. When the counter overflows,
- RRDtool checks if the overflow happened at the 32bit or 64bit
- border and acts accordingly by adding an appropriate value to
- the result.
-
- D\bDE\bER\bRI\bIV\bVE\bE
- will store the derivative of the line going from the last to
- the current value of the data source. This can be useful for
- gauges, for example, to measure the rate of people entering or
- leaving a room. Internally, derive works exactly like COUNTER
- but without overflow checks. So if your counter does not reset
- at 32 or 64 bit you might want to use DERIVE and combine it
- with a MIN value of 0.
-
- NOTE on COUNTER vs DERIVE
-
- by Don Baarda <don.baarda@baesystems.com>
-
- If you cannot tolerate ever mistaking the occasional counter
- reset for a legitimate counter wrap, and would prefer
- "Unknowns" for all legitimate counter wraps and resets, always
- use DERIVE with min=0. Otherwise, using COUNTER with a suitable
- max will return correct values for all legitimate counter
- wraps, mark some counter resets as "Unknown", but can mistake
- some counter resets for a legitimate counter wrap.
-
- For a 5 minute step and 32-bit counter, the probability of mis-
- taking a counter reset for a legitimate wrap is arguably about
- 0.8% per 1Mbps of maximum bandwidth. Note that this equates to
- 80% for 100Mbps interfaces, so for high bandwidth interfaces
- and a 32bit counter, DERIVE with min=0 is probably preferable.
- If you are using a 64bit counter, just about any max setting
- will eliminate the possibility of mistaking a reset for a
- counter wrap.
-
- A\bAB\bBS\bSO\bOL\bLU\bUT\bTE\bE
- is for counters which get reset upon reading. This is used for
- fast counters which tend to overflow. So instead of reading
- them normally you reset them after every read to make sure you
- have a maximum time available before the next overflow. Another
- usage is for things you count like number of messages since the
- last update.
-
- C\bCO\bOM\bMP\bPU\bUT\bTE\bE
- is for storing the result of a formula applied to other data
- sources in the R\bRR\bRD\bD. This data source is not supplied a value on
- update, but rather its Primary Data Points (PDPs) are computed
- from the PDPs of the data sources according to the rpn-expres-
- sion that defines the formula. Consolidation functions are then
- applied normally to the PDPs of the COMPUTE data source (that
- is the rpn-expression is only applied to generate PDPs). In
- database software, such data sets are referred to as "virtual"
- or "computed" columns.
-
- _\bh_\be_\ba_\br_\bt_\bb_\be_\ba_\bt defines the maximum number of seconds that may pass
- between two updates of this data source before the value of the
- data source is assumed to be _\b*_\bU_\bN_\bK_\bN_\bO_\bW_\bN_\b*.
-
- _\bm_\bi_\bn and _\bm_\ba_\bx define the expected range values for data supplied by a
- data source. If _\bm_\bi_\bn and/or _\bm_\ba_\bx any value outside the defined range
- will be regarded as _\b*_\bU_\bN_\bK_\bN_\bO_\bW_\bN_\b*. If you do not know or care about min
- and max, set them to U for unknown. Note that min and max always
- refer to the processed values of the DS. For a traffic-C\bCO\bOU\bUN\bNT\bTE\bER\bR type
- DS this would be the maximum and minimum data-rate expected from
- the device.
-
- _\bI_\bf _\bi_\bn_\bf_\bo_\br_\bm_\ba_\bt_\bi_\bo_\bn _\bo_\bn _\bm_\bi_\bn_\bi_\bm_\ba_\bl_\b/_\bm_\ba_\bx_\bi_\bm_\ba_\bl _\be_\bx_\bp_\be_\bc_\bt_\be_\bd _\bv_\ba_\bl_\bu_\be_\bs _\bi_\bs _\ba_\bv_\ba_\bi_\bl_\ba_\bb_\bl_\be_\b,
- _\ba_\bl_\bw_\ba_\by_\bs _\bs_\be_\bt _\bt_\bh_\be _\bm_\bi_\bn _\ba_\bn_\bd_\b/_\bo_\br _\bm_\ba_\bx _\bp_\br_\bo_\bp_\be_\br_\bt_\bi_\be_\bs_\b. _\bT_\bh_\bi_\bs _\bw_\bi_\bl_\bl _\bh_\be_\bl_\bp _\bR_\bR_\bD_\bt_\bo_\bo_\bl _\bi_\bn
- _\bd_\bo_\bi_\bn_\bg _\ba _\bs_\bi_\bm_\bp_\bl_\be _\bs_\ba_\bn_\bi_\bt_\by _\bc_\bh_\be_\bc_\bk _\bo_\bn _\bt_\bh_\be _\bd_\ba_\bt_\ba _\bs_\bu_\bp_\bp_\bl_\bi_\be_\bd _\bw_\bh_\be_\bn _\br_\bu_\bn_\bn_\bi_\bn_\bg
- _\bu_\bp_\bd_\ba_\bt_\be_\b.
-
- _\br_\bp_\bn_\b-_\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn defines the formula used to compute the PDPs of a
- COMPUTE data source from other data sources in the same <RRD>. It
- is similar to defining a C\bCD\bDE\bEF\bF argument for the graph command.
- Please refer to that manual page for a list and description of RPN
- operations supported. For COMPUTE data sources, the following RPN
- operations are not supported: COUNT, PREV, TIME, and LTIME. In
- addition, in defining the RPN expression, the COMPUTE data source
- may only refer to the names of data source listed previously in the
- create command. This is similar to the restriction that C\bCD\bDE\bEF\bFs must
- refer only to D\bDE\bEF\bFs and C\bCD\bDE\bEF\bFs previously defined in the same graph
- command.
+ A single R\bRR\bRD\bD can accept input from several data sources (D\bDS\bS),
+ for example incoming and outgoing traffic on a specific commu-
+ nication line. With the D\bDS\bS configuration option you must define
+ some basic properties of each data source you want to store in
+ the R\bRR\bRD\bD.
+
+ _\bd_\bs_\b-_\bn_\ba_\bm_\be is the name you will use to reference this particular
+ data source from an R\bRR\bRD\bD. A _\bd_\bs_\b-_\bn_\ba_\bm_\be must be 1 to 19 characters
+ long in the characters [a-zA-Z0-9_].
+
+ _\bD_\bS_\bT defines the Data Source Type. The remaining arguments of a
+ data source entry depend on the data source type. For GAUGE,
+ COUNTER, DERIVE, and ABSOLUTE the format for a data source
+ entry is:
+
+ D\bDS\bS:\b:_\bd_\bs_\b-_\bn_\ba_\bm_\be:\b:_\bG_\bA_\bU_\bG_\bE _\b| _\bC_\bO_\bU_\bN_\bT_\bE_\bR _\b| _\bD_\bE_\bR_\bI_\bV_\bE _\b| _\bA_\bB_\bS_\bO_\bL_\bU_\bT_\bE:\b:_\bh_\be_\ba_\br_\bt_\b-
+ _\bb_\be_\ba_\bt:\b:_\bm_\bi_\bn:\b:_\bm_\ba_\bx
+
+ For COMPUTE data sources, the format is:
+
+ D\bDS\bS:\b:_\bd_\bs_\b-_\bn_\ba_\bm_\be:\b:_\bC_\bO_\bM_\bP_\bU_\bT_\bE:\b:_\br_\bp_\bn_\b-_\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn
+
+ In order to decide which data source type to use, review the
+ definitions that follow. Also consult the section on "HOW TO
+ MEASURE" for further insight.
+
+ G\bGA\bAU\bUG\bGE\bE
+ is for things like temperatures or number of people in a
+ room or the value of a RedHat share.
+
+ C\bCO\bOU\bUN\bNT\bTE\bER\bR
+ is for continuous incrementing counters like the ifInOctets
+ counter in a router. The C\bCO\bOU\bUN\bNT\bTE\bER\bR data source assumes that
+ the counter never decreases, except when a counter over-
+ flows. The update function takes the overflow into
+ account. The counter is stored as a per-second rate. When
+ the counter overflows, RRDtool checks if the overflow hap-
+ pened at the 32bit or 64bit border and acts accordingly by
+ adding an appropriate value to the result.
+
+ D\bDE\bER\bRI\bIV\bVE\bE
+ will store the derivative of the line going from the last
+ to the current value of the data source. This can be useful
+ for gauges, for example, to measure the rate of people
+ entering or leaving a room. Internally, derive works
+ exactly like COUNTER but without overflow checks. So if
+ your counter does not reset at 32 or 64 bit you might want
+ to use DERIVE and combine it with a MIN value of 0.
+
+ NOTE on COUNTER vs DERIVE
+ by Don Baarda <don.baarda@baesystems.com>
+
+ If you cannot tolerate ever mistaking the occasional
+ counter reset for a legitimate counter wrap, and would
+ prefer "Unknowns" for all legitimate counter wraps and
+ resets, always use DERIVE with min=0. Otherwise, using
+ COUNTER with a suitable max will return correct values
+ for all legitimate counter wraps, mark some counter
+ resets as "Unknown", but can mistake some counter
+ resets for a legitimate counter wrap.
+
+ For a 5 minute step and 32-bit counter, the probability
+ of mistaking a counter reset for a legitimate wrap is
+ arguably about 0.8% per 1Mbps of maximum bandwidth.
+ Note that this equates to 80% for 100Mbps interfaces,
+ so for high bandwidth interfaces and a 32bit counter,
+ DERIVE with min=0 is probably preferable. If you are
+ using a 64bit counter, just about any max setting will
+ eliminate the possibility of mistaking a reset for a
+ counter wrap.
+
+ A\bAB\bBS\bSO\bOL\bLU\bUT\bTE\bE
+ is for counters which get reset upon reading. This is used
+ for fast counters which tend to overflow. So instead of
+ reading them normally you reset them after every read to
+ make sure you have a maximum time available before the next
+ overflow. Another usage is for things you count like number
+ of messages since the last update.
+
+ C\bCO\bOM\bMP\bPU\bUT\bTE\bE
+ is for storing the result of a formula applied to other
+ data sources in the R\bRR\bRD\bD. This data source is not supplied a
+ value on update, but rather its Primary Data Points (PDPs)
+ are computed from the PDPs of the data sources according to
+ the rpn-expression that defines the formula. Consolidation
+ functions are then applied normally to the PDPs of the COM-
+ PUTE data source (that is the rpn-expression is only
+ applied to generate PDPs). In database software, such data
+ sets are referred to as "virtual" or "computed" columns.
+
+ _\bh_\be_\ba_\br_\bt_\bb_\be_\ba_\bt defines the maximum number of seconds that may pass
+ between two updates of this data source before the value of the
+ data source is assumed to be _\b*_\bU_\bN_\bK_\bN_\bO_\bW_\bN_\b*.
+
+ _\bm_\bi_\bn and _\bm_\ba_\bx define the expected range values for data supplied
+ by a data source. If _\bm_\bi_\bn and/or _\bm_\ba_\bx any value outside the
+ defined range will be regarded as _\b*_\bU_\bN_\bK_\bN_\bO_\bW_\bN_\b*. If you do not know
+ or care about min and max, set them to U for unknown. Note that
+ min and max always refer to the processed values of the DS. For
+ a traffic-C\bCO\bOU\bUN\bNT\bTE\bER\bR type DS this would be the maximum and minimum
+ data-rate expected from the device.
+
+ _\bI_\bf _\bi_\bn_\bf_\bo_\br_\bm_\ba_\bt_\bi_\bo_\bn _\bo_\bn _\bm_\bi_\bn_\bi_\bm_\ba_\bl_\b/_\bm_\ba_\bx_\bi_\bm_\ba_\bl _\be_\bx_\bp_\be_\bc_\bt_\be_\bd _\bv_\ba_\bl_\bu_\be_\bs _\bi_\bs _\ba_\bv_\ba_\bi_\bl_\ba_\bb_\bl_\be_\b,
+ _\ba_\bl_\bw_\ba_\by_\bs _\bs_\be_\bt _\bt_\bh_\be _\bm_\bi_\bn _\ba_\bn_\bd_\b/_\bo_\br _\bm_\ba_\bx _\bp_\br_\bo_\bp_\be_\br_\bt_\bi_\be_\bs_\b. _\bT_\bh_\bi_\bs _\bw_\bi_\bl_\bl _\bh_\be_\bl_\bp _\bR_\bR_\bD_\b-
+ _\bt_\bo_\bo_\bl _\bi_\bn _\bd_\bo_\bi_\bn_\bg _\ba _\bs_\bi_\bm_\bp_\bl_\be _\bs_\ba_\bn_\bi_\bt_\by _\bc_\bh_\be_\bc_\bk _\bo_\bn _\bt_\bh_\be _\bd_\ba_\bt_\ba _\bs_\bu_\bp_\bp_\bl_\bi_\be_\bd _\bw_\bh_\be_\bn
+ _\br_\bu_\bn_\bn_\bi_\bn_\bg _\bu_\bp_\bd_\ba_\bt_\be_\b.
+
+ _\br_\bp_\bn_\b-_\be_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn defines the formula used to compute the PDPs of
+ a COMPUTE data source from other data sources in the same
+ <RRD>. It is similar to defining a C\bCD\bDE\bEF\bF argument for the graph
+ command. Please refer to that manual page for a list and
+ description of RPN operations supported. For COMPUTE data
+ sources, the following RPN operations are not supported: COUNT,
+ PREV, TIME, and LTIME. In addition, in defining the RPN expres-
+ sion, the COMPUTE data source may only refer to the names of
+ data source listed previously in the create command. This is
+ similar to the restriction that C\bCD\bDE\bEF\bFs must refer only to D\bDE\bEF\bFs
+ and C\bCD\bDE\bEF\bFs previously defined in the same graph command.
R\bRR\bRA\bA:\b:_\bC_\bF:\b:_\bc_\bf _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs
- The purpose of an R\bRR\bRD\bD is to store data in the round robin archives
- (R\bRR\bRA\bA). An archive consists of a number of data values or statistics
- for each of the defined data-sources (D\bDS\bS) and is defined with an
- R\bRR\bRA\bA line.
+ The purpose of an R\bRR\bRD\bD is to store data in the round robin
+ archives (R\bRR\bRA\bA). An archive consists of a number of data values
+ or statistics for each of the defined data-sources (D\bDS\bS) and is
+ defined with an R\bRR\bRA\bA line.
- When data is entered into an R\bRR\bRD\bD, it is first fit into time slots
- of the length defined with the -\b-s\bs option, thus becoming a _\bp_\br_\bi_\bm_\ba_\br_\by
- _\bd_\ba_\bt_\ba _\bp_\bo_\bi_\bn_\bt.
+ When data is entered into an R\bRR\bRD\bD, it is first fit into time
+ slots of the length defined with the -\b-s\bs option, thus becoming a
+ _\bp_\br_\bi_\bm_\ba_\br_\by _\bd_\ba_\bt_\ba _\bp_\bo_\bi_\bn_\bt.
- The data is also processed with the consolidation function (_\bC_\bF) of
- the archive. There are several consolidation functions that consol-
- idate primary data points via an aggregate function: A\bAV\bVE\bER\bRA\bAG\bGE\bE, M\bMI\bIN\bN,
- M\bMA\bAX\bX, L\bLA\bAS\bST\bT. The format of R\bRR\bRA\bA line for these consolidation functions
- is:
+ The data is also processed with the consolidation function (_\bC_\bF)
+ of the archive. There are several consolidation functions that
+ consolidate primary data points via an aggregate function:
+ A\bAV\bVE\bER\bRA\bAG\bGE\bE, M\bMI\bIN\bN, M\bMA\bAX\bX, L\bLA\bAS\bST\bT.
- R\bRR\bRA\bA:\b:_\bA_\bV_\bE_\bR_\bA_\bG_\bE _\b| _\bM_\bI_\bN _\b| _\bM_\bA_\bX _\b| _\bL_\bA_\bS_\bT:\b:_\bx_\bf_\bf:\b:_\bs_\bt_\be_\bp_\bs:\b:_\br_\bo_\bw_\bs
+ AVERAGE
+ the average of the data points is stored.
- _\bx_\bf_\bf The xfiles factor defines what part of a consolidation interval
- may be made up from _\b*_\bU_\bN_\bK_\bN_\bO_\bW_\bN_\b* data while the consolidated value is
- still regarded as known. It is given as the ratio of allowed
- _\b*_\bU_\bN_\bK_\bN_\bO_\bW_\bN_\b* PDPs to the number of PDPs in the interval. Thus, it
- ranges from 0 to 1 (exclusive).
+ MIN the smallest of the data points is stored.
- _\bs_\bt_\be_\bp_\bs defines how many of these _\bp_\br_\bi_\bm_\ba_\br_\by _\bd_\ba_\bt_\ba _\bp_\bo_\bi_\bn_\bt_\bs are used to
- build a _\bc_\bo_\bn_\bs_\bo_\bl_\bi_\bd_\ba_\bt_\be_\bd _\bd_\ba_\bt_\ba _\bp_\bo_\bi_\bn_\bt which then goes into the archive.
+ MAX the largest of the data points is stored.
- _\br_\bo_\bw_\bs defines how many generations of data values are kept in an
- R\bRR\bRA\bA.
+ LAST
+ the last data points is used.
+
+ Note that data aggregation inevitably leads to loss of preci-
+ sion and information. The trick is to pick the aggregate func-
+ tion such that the _\bi_\bn_\bt_\be_\br_\be_\bs_\bt_\bi_\bn_\bg properties of your data is kept
+ across the aggregation process.
+
+ The format of R\bRR\bRA\bA line for these consolidation functions is:
+
+ R\bRR\bRA\bA:\b:_\bA_\bV_\bE_\bR_\bA_\bG_\bE _\b| _\bM_\bI_\bN _\b| _\bM_\bA_\bX _\b| _\bL_\bA_\bS_\bT:\b:_\bx_\bf_\bf:\b:_\bs_\bt_\be_\bp_\bs:\b:_\br_\bo_\bw_\bs
+
+ _\bx_\bf_\bf The xfiles factor defines what part of a consolidation
+ interval may be made up from _\b*_\bU_\bN_\bK_\bN_\bO_\bW_\bN_\b* data while the consoli-
+ dated value is still regarded as known. It is given as the
+ ratio of allowed _\b*_\bU_\bN_\bK_\bN_\bO_\bW_\bN_\b* PDPs to the number of PDPs in the
+ interval. Thus, it ranges from 0 to 1 (exclusive).
+
+ _\bs_\bt_\be_\bp_\bs defines how many of these _\bp_\br_\bi_\bm_\ba_\br_\by _\bd_\ba_\bt_\ba _\bp_\bo_\bi_\bn_\bt_\bs are used to
+ build a _\bc_\bo_\bn_\bs_\bo_\bl_\bi_\bd_\ba_\bt_\be_\bd _\bd_\ba_\bt_\ba _\bp_\bo_\bi_\bn_\bt which then goes into the
+ archive.
+
+ _\br_\bo_\bw_\bs defines how many generations of data values are kept in an
+ R\bRR\bRA\bA.
A\bAb\bbe\ber\brr\bra\ban\bnt\bt B\bBe\beh\bha\bav\bvi\bio\bor\br D\bDe\bet\bte\bec\bct\bti\bio\bon\bn w\bwi\bit\bth\bh H\bHo\bol\blt\bt-\b-W\bWi\bin\bnt\bte\ber\brs\bs F\bFo\bor\bre\bec\bca\bas\bst\bti\bin\bng\bg
In addition to the aggregate functions, there are a set of specialized
@@ -184,9 +206,13 @@ A\bAb\bbe\ber\brr\bra\ban\bnt\bt B\bBe\beh\bha\bav\bvi\bio\bor\br D\bDe\bet\bte\bec\bct\bti\bio\bon\bn w\b
· R\bRR\bRA\bA:\b:_\bH_\bW_\bP_\bR_\bE_\bD_\bI_\bC_\bT:\b:_\br_\bo_\bw_\bs:\b:_\ba_\bl_\bp_\bh_\ba:\b:_\bb_\be_\bt_\ba:\b:_\bs_\be_\ba_\bs_\bo_\bn_\ba_\bl _\bp_\be_\br_\bi_\bo_\bd[:\b:_\br_\br_\ba_\b-_\bn_\bu_\bm]
- · R\bRR\bRA\bA:\b:_\bS_\bE_\bA_\bS_\bO_\bN_\bA_\bL:\b:_\bs_\be_\ba_\bs_\bo_\bn_\ba_\bl _\bp_\be_\br_\bi_\bo_\bd:\b:_\bg_\ba_\bm_\bm_\ba:\b:_\br_\br_\ba_\b-_\bn_\bu_\bm
+ · R\bRR\bRA\bA:\b:_\bM_\bH_\bW_\bP_\bR_\bE_\bD_\bI_\bC_\bT:\b:_\br_\bo_\bw_\bs:\b:_\ba_\bl_\bp_\bh_\ba:\b:_\bb_\be_\bt_\ba:\b:_\bs_\be_\ba_\bs_\bo_\bn_\ba_\bl _\bp_\be_\br_\bi_\bo_\bd[:\b:_\br_\br_\ba_\b-_\bn_\bu_\bm]
- · R\bRR\bRA\bA:\b:_\bD_\bE_\bV_\bS_\bE_\bA_\bS_\bO_\bN_\bA_\bL:\b:_\bs_\be_\ba_\bs_\bo_\bn_\ba_\bl _\bp_\be_\br_\bi_\bo_\bd:\b:_\bg_\ba_\bm_\bm_\ba:\b:_\br_\br_\ba_\b-_\bn_\bu_\bm
+ · R\bRR\bRA\bA:\b:_\bS_\bE_\bA_\bS_\bO_\bN_\bA_\bL:\b:_\bs_\be_\ba_\bs_\bo_\bn_\ba_\bl _\bp_\be_\br_\bi_\bo_\bd:\b:_\bg_\ba_\bm_\bm_\ba:\b:_\br_\br_\ba_\b-_\bn_\bu_\bm[:\b:s\bsm\bmo\boo\bot\bth\bhi\bin\bng\bg-\b-w\bwi\bin\bnd\bdo\bow\bw=\b=_\bf_\br_\ba_\bc_\b-
+ _\bt_\bi_\bo_\bn]
+
+ · R\bRR\bRA\bA:\b:_\bD_\bE_\bV_\bS_\bE_\bA_\bS_\bO_\bN_\bA_\bL:\b:_\bs_\be_\ba_\bs_\bo_\bn_\ba_\bl _\bp_\be_\br_\bi_\bo_\bd:\b:_\bg_\ba_\bm_\bm_\ba:\b:_\br_\br_\ba_\b-_\bn_\bu_\bm[:\b:s\bsm\bmo\boo\bot\bth\bhi\bin\bng\bg-\b-w\bwi\bin\bn-\b-
+ d\bdo\bow\bw=\b=_\bf_\br_\ba_\bc_\bt_\bi_\bo_\bn]
· R\bRR\bRA\bA:\b:_\bD_\bE_\bV_\bP_\bR_\bE_\bD_\bI_\bC_\bT:\b:_\br_\bo_\bw_\bs:\b:_\br_\br_\ba_\b-_\bn_\bu_\bm
@@ -195,20 +221,34 @@ A\bAb\bbe\ber\brr\bra\ban\bnt\bt B\bBe\beh\bha\bav\bvi\bio\bor\br D\bDe\bet\bte\bec\bct\bti\bio\bon\bn w\b
These R\bRR\bRA\bAs\bs differ from the true consolidation functions in several
ways. First, each of the R\bRR\bRA\bAs is updated once for every primary data
point. Second, these R\bRR\bRA\bAs\bs are interdependent. To generate real-time
- confidence bounds, a matched set of HWPREDICT, SEASONAL, DEVSEASONAL,
- and DEVPREDICT must exist. Generating smoothed values of the primary
- data points requires both a HWPREDICT R\bRR\bRA\bA and SEASONAL R\bRR\bRA\bA. Aberrant
- behavior detection requires FAILURES, HWPREDICT, DEVSEASONAL, and SEA-
- SONAL.
-
- The actual predicted, or smoothed, values are stored in the HWPREDICT
- R\bRR\bRA\bA. The predicted deviations are stored in DEVPREDICT (think a stan-
- dard deviation which can be scaled to yield a confidence band). The
- FAILURES R\bRR\bRA\bA stores binary indicators. A 1 marks the indexed observa-
- tion as failure; that is, the number of confidence bounds violations in
- the preceding window of observations met or exceeded a specified
- threshold. An example of using these R\bRR\bRA\bAs\bs to graph confidence bounds
- and failures appears in rrdgraph.
+ confidence bounds, a matched set of SEASONAL, DEVSEASONAL, DEVPREDICT,
+ and either HWPREDICT or MHWPREDICT must exist. Generating smoothed val-
+ ues of the primary data points requires a SEASONAL R\bRR\bRA\bA and either an
+ HWPREDICT or MHWPREDICT R\bRR\bRA\bA. Aberrant behavior detection requires FAIL-
+ URES, DEVSEASONAL, SEASONAL, and either HWPREDICT or MHWPREDICT.
+
+ The predicted, or smoothed, values are stored in the HWPREDICT or MHW-
+ PREDICT R\bRR\bRA\bA. HWPREDICT and MHWPREDICT are actually two variations on
+ the Holt-Winters method. They are interchangeable. Both attempt to
+ decompose data into three components: a baseline, a trend, and a sea-
+ sonal coefficient. HWPREDICT adds its seasonal coefficient to the
+ baseline to form a prediction, whereas MHWPREDICT multiplies its sea-
+ sonal coefficient by the baseline to form a prediction. The difference
+ is noticeable when the baseline changes significantly in the course of
+ a season; HWPREDICT will predict the seasonality to stay constant as
+ the baseline changes, but MHWPREDICT will predict the seasonality to
+ grow or shrink in proportion to the baseline. The proper choice of
+ method depends on the thing being modeled. For simplicity, the rest of
+ this discussion will refer to HWPREDICT, but MHWPREDICT may be substi-
+ tuted in its place.
+
+ The predicted deviations are stored in DEVPREDICT (think a standard
+ deviation which can be scaled to yield a confidence band). The FAILURES
+ R\bRR\bRA\bA stores binary indicators. A 1 marks the indexed observation as
+ failure; that is, the number of confidence bounds violations in the
+ preceding window of observations met or exceeded a specified threshold.
+ An example of using these R\bRR\bRA\bAs\bs to graph confidence bounds and failures
+ appears in rrdgraph.
The SEASONAL and DEVSEASONAL R\bRR\bRA\bAs\bs store the seasonal coefficients for
the Holt-Winters forecasting algorithm and the seasonal deviations,
@@ -269,6 +309,13 @@ A\bAb\bbe\ber\brr\bra\ban\bnt\bt B\bBe\beh\bha\bav\bvi\bio\bor\br D\bDe\bet\bte\bec\bct\bti\bio\bon\bn w\b
be the same for both. Note that _\bg_\ba_\bm_\bm_\ba can also be changed via the R\bRR\bRD\bD-\b-
t\bto\boo\bol\bl _\bt_\bu_\bn_\be command.
+ _\bs_\bm_\bo_\bo_\bt_\bh_\bi_\bn_\bg_\b-_\bw_\bi_\bn_\bd_\bo_\bw specifies the fraction of a season that should be
+ averaged around each point. By default, the value of _\bs_\bm_\bo_\bo_\bt_\bh_\bi_\bn_\bg_\b-_\bw_\bi_\bn_\bd_\bo_\bw
+ is 0.05, which means each value in SEASONAL and DEVSEASONAL will be
+ occasionally replaced by averaging it with its (_\bs_\be_\ba_\bs_\bo_\bn_\ba_\bl _\bp_\be_\br_\bi_\bo_\bd*0.05)
+ nearest neighbors. Setting _\bs_\bm_\bo_\bo_\bt_\bh_\bi_\bn_\bg_\b-_\bw_\bi_\bn_\bd_\bo_\bw to zero will disable the
+ running-average smoother altogether.
+
_\br_\br_\ba_\b-_\bn_\bu_\bm provides the links between related R\bRR\bRA\bAs\bs. If HWPREDICT is speci-
fied alone and the other R\bRR\bRA\bAs\bs are created implicitly, then there is no
need to worry about this argument. If R\bRR\bRA\bAs\bs are created explicitly, then
@@ -303,28 +350,24 @@ T\bTh\bhe\be H\bHE\bEA\bAR\bRT\bTB\bBE\bEA\bAT\bT a\ban\bnd\bd t\bth\bhe\be S\bST\bTE\bEP\bP
It may help you to sort out why all this *UNKNOWN* data is popping up
in your databases:
- RRDtool gets fed samples at arbitrary times. From these it builds Pri-
- mary Data Points (PDPs) at exact times on every "step" interval. The
- PDPs are then accumulated into RRAs.
+ RRDtool gets fed samples/updates at arbitrary times. From these it
+ builds Primary Data Points (PDPs) on every "step" interval. The PDPs
+ are then accumulated into the RRAs.
The "heartbeat" defines the maximum acceptable interval between sam-
- ples. If the interval between samples is less than "heartbeat", then an
- average rate is calculated and applied for that interval. If the inter-
- val between samples is longer than "heartbeat", then that entire inter-
- val is considered "unknown". Note that there are other things that can
- make a sample interval "unknown", such as the rate exceeding limits, or
- even an "unknown" input sample.
+ ples/updates. If the interval between samples is less than "heartbeat",
+ then an average rate is calculated and applied for that interval. If
+ the interval between samples is longer than "heartbeat", then that
+ entire interval is considered "unknown". Note that there are other
+ things that can make a sample interval "unknown", such as the rate
+ exceeding limits, or a sample that was explicitly marked as unknown.
The known rates during a PDP's "step" interval are used to calculate an
- average rate for that PDP. Also, if the total "unknown" time during the
- "step" interval exceeds the "heartbeat", the entire PDP is marked as
- "unknown". This means that a mixture of known and "unknown" sample
- times in a single PDP "step" may or may not add up to enough "unknown"
- time to exceed "heartbeat" and hence mark the whole PDP "unknown". So
- "heartbeat" is not only the maximum acceptable interval between sam-
- ples, but also the maximum acceptable amount of "unknown" time per PDP
- (obviously this is only significant if you have "heartbeat" less than
- "step").
+ average rate for that PDP. If the total "unknown" time accounts for
+ more than h\bha\bal\blf\bf the "step", the entire PDP is marked as "unknown". This
+ means that a mixture of known and "unknown" sample times in a single
+ PDP "step" may or may not add up to enough "known" time to warrent for
+ a known PDP.
The "heartbeat" can be short (unusual) or long (typical) relative to
the "step" interval between PDPs. A short "heartbeat" means you require
@@ -356,7 +399,7 @@ T\bTh\bhe\be H\bHE\bEA\bAR\bRT\bTB\bBE\bEA\bAT\bT a\ban\bnd\bd t\bth\bhe\be S\bST\bTE\bEP\bP
u|15|/ "swt" expired
u|16|
|17|----* sample4, restart "hb", create "pdp" for step1 =
- |18| / = unknown due to 10 "u" labled secs > "hb"
+ |18| / = unknown due to 10 "u" labled secs > 0.5 * step
|19| /
|20| /
|21|----* sample5, restart "hb"
-1.2.27 2008-02-17 RRDCREATE(1)
+1.3rc4 2008-05-12 RRDCREATE(1)