Ubuntu Manpage: pmlogcheck - checks for invalid data in a PCP archive

NAME

       pmlogcheck - checks for invalid data in a PCP archive

SYNOPSIS

       pmlogcheck [-lmvwz?]  [-n pmnsfile] [-S start] [-T finish] [-Z timezone] archive

DESCRIPTION

       pmlogcheck prints information about the nature of any invalid data which it detects in the
       files of a PCP archive.

       The archive has the base  name  archive  and  must  have  been  previously  created  using
       pmlogger(1).

OPTIONS

The available command line options are:

-l, --label
Print the archive label, showing the log format version, the time and date for the
start and (current) end of the archive, and the host from which the performance
metrics values were collected.

-m, --metadataonly
Skip Pass 3 (see below) and only check the archive meta data. This can run
substantially faster in cases where the volume data doesn't need to be checked,
especially on archives with compressed data volume(s).

-n pmnsfile, --namespace=pmnsfile
Load an alternative Performance Metrics Name Space (PMNS(5)) from the file pmnsfile.

-S starttime, --start=starttime
Specify the starttime of time window over which metrics should be checked in Pass 3
(see below). Refer to PCPIntro(1) for a complete description of the syntax for
starttime.

-T endtime, --finish=endtime
Specify the endtime of time window over which metrics should be checked in Pass 3
(see below). Refer to PCPIntro(1) for a complete description of the syntax for
endtime.

-v, --verbose
Enable verbose mode.

-z, --hostzone
Use the local timezone of the host that is the source of the performance metrics
archive. The default is to use the timezone of the local host.

-Z timezone, --timezone=timezone
Use timezone for the date and time. Timezone is in the format of the environment
variable TZ as described in environ(7). The default is to use the timezone of the
local host.

-?, --help
Display usage message and exit.

OPERATION

The checking proceeds in a number of passes, each designed to validate progressively more
complex semantic relationships between the information in a PCP archive.

Pass 0
Each physical file of the PCP archive is processed to ensure the label records are valid
and consistent, and that each file contains an integral number of physical records with
correct header and trailer fields.

Any errors at this stage are usually fatal. The PCP archive is probably damaged beyond
repair, and no more passes of pmlogcheck are attempted.

Pass 1
Validates the integrity of the temporal index, usually archive.index.

As the temporal index is (strictly speaking) optional, errors at this stage are handled by
marking the index as bad and ignoring it for the remainder of the pmlogcheck passes.

Permanent repair can be achieved by removing the temporal index file and then making a
copy of the PCP archive using pmlogrewrite(1) or pmlogextract(1). This will create a new
temporal index for the copied archive as a side-effect.

Pass 2
Validates the integrity of the metadata file, usually archive.meta.

Pass 3
Validates the integrity of each of the log volumes of the PCP archive, usually archive.0,
archive.1, etc.

There is some basic integrity checks to ensure the encoding of values for each metric
remains consistent and the values are well formed across all the observations in the
archive.

Also the timestamps for the observations are expected to be monotonically increasing as
the archive is tranversed.

Additional attention is given to counter metrics (type from pmLookupDesc(3) is
PM_SEM_COUNTER) which are expected to have monotonically increasing values. If the values
are not monotonic increasing this may suggest a counter wrap has happened or there has
been some interruption or reset to the underlying source of the performance data that is
no captured in the archive.

For each counter metric which has been detected as having wrapped at some point in the
archive, pmlogcheck produces output describing the metric name (with instance identifiers
where appropriate), the internal storage type for the metric, the value of the metric
before the counter wrap (with its associated timestamp), and the value of the metric after
the wrap (also with a timestamp).

The -w option may be used to suppress reporting of counter wraps.

pmlogcheck produces two different timestamp formats, depending on the interval over which
it is run. For an interval greater than 24 hours, the date is displayed in addition to
the time at which the counter wrap occurred. If the extent of the data being checked is
less than 24 hours, a more precise format is used (time is displayed with millisecond
precision, but without the date).

DIAGNOSTICS

       All are generated on standard error and are intended to be self- explanatory.

FILES

       $PCP_VAR_DIR/pmns/*
            default PMNS specification files

       $PCP_LOG_DIR/pmlogger/<hostname>
            default  directory  for  PCP  archives containing performance data collected from the
            host hostname.

PCP ENVIRONMENT

       Environment variables with the prefix PCP_ are used to parameterize the file and directory
       names used by PCP.  On each installation, the file /etc/pcp.conf contains the local values
       for these variables.  The $PCP_CONF  variable  may  be  used  to  specify  an  alternative
       configuration file, as described in pcp.conf(5).