pmlogcheck - Man Page

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 PCP archives.

Each archive has the base name archive and must have been previously created using pmlogger(1). Alternatively, archive can be the name of a physical file that forms part of a PCP archive.

When multiple archive options are present, all of the corresponding PCP archives will be checked, however if the archive options are file names, then each associated PCP archive will be checked at most once.

Options

The available command line options are:

-l, --label: Print the archive label, showing the archive 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.
-w, --nowrap: Suppress reporting of counter wraps.
-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 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 traversed.

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).

Examples

The following are all equivalent:

$ pmlogcheck myarchive
$ pmlogcheck myarchive.0
$ pmlogcheck myarchive.meta
$ pmlogcheck myarchive.0 myarchive.meta

If the current directory contains multiple PCP archives, then the command

$ pmlogcheck *.meta*

will check them all, as there is one .meta file for each PCP archive, but this file may have been compressed (hence the trailing *).

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).

Referenced By

pmlogdump(1), pmloglabel(1), pmlogsize(1).

PCP Performance Co-Pilot