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Oracle Light Weight Availability Collection Tool User Guide

Understanding Availability Datagram Structure

The availability data collected by the Oracle Lightweight Availability Collection Tool is stored in the form of datagram within the file system of the monitored host. The availability data is embedded in between XML tags. The Availability datagram can be broadly categorized into two sections:

The following is a sample of an Oracle Lightweight Availability Collection Tool Availability datagram file.


<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<single_system_availability_results>
    <systemInfo>
       <hostName>bs6-s0</hostName>
       <hostId>83254cb1</hostId>
       <zoneName>global</zoneName>
       <timeZone>US/Mountain</timeZone>
       <sysSerialNumber>unknown</sysSerialNumber>
       <OSName>SunOS</OSName>
       <OSVersion>5.10</OSVersion>
       <cpuArchitecture>sparc</cpuArchitecture>
       <productType>Serverblade1</productType>
       <lwactVersion>3.1</lwactVersion>
    </systemInfo>
  <event type="epoch" utc="1207784519" timeStamp="Wed Apr  9 17:41:59 2008" 
    up="0" dwnPlnd="0" dwnUnplnd="0" dwnUndef="0" cksum="13c8" />
  <event type="boot" utc="1207784519" timeStamp="Wed Apr  9 17:41:59 2008" 
   up="76820" dwnPlnd="0" dwnUnplnd="0" dwnUndef="0" cksum="13e4" />
  <event type="panic" utc="1207861339" timeStamp="Thu Apr 10 15:02:19 
    2008 -06:00" up="0" dwnPlnd="0" dwnUnplnd="1" dwnUndef="0" L1causeCode="Unplanned" 
    L2causeCode="Undefined" L3causeCode="Undefined" wasPlanned="2" cksum="2708" />
  <event type="boot" utc="1207861340" timeStamp="Thu Apr 10 15:02:20 2008 -06:00" 
   up="8931" dwnPlnd="0" dwnUnplnd="0" dwnUndef="0" cksum="143b" />
  <event type="time" utc="1207870271" timeStamp="Thu Apr 10 17:31:11 2008 -06:00" 
   up="85751" dwnPlnd="0" dwnUnplnd="1" dwnUndef="0" elapsed="85752" totAvail="99.999" 
    adjAvail="99.999" cksum="1c95" />
</single_system_availability_results>
Note –

In this sample datagram file, the epoch and boot events do not have a time zone offset. This might happen if you upgrade the Oracle Lightweight Availability Collection Tool from a pre-3.0 version to a later one. The latest Oracle Lightweight Availability Collection Tool will always contain time zone offset information in the event timestamps.

The information collected in between the tags <systemInfo> and </systemInfo> constitutes the system information section. This section provides details about the monitored host, such as the following:

The Availability Data section contains the availability events (boot, epoch, halt, panic) and its corresponding timestamp. All the availability calculations are done based on the data collected under this section.

Important Fields in the Availability Datagram

This section identifies and describes the important fields of the Availability datagram (listed here in alphabetical order).

Field Name

Definition

Adjusted availability

Represented in percentage as: ((Total uptime + Total Planned downtime) /Total elapsed time) * 100

Note –

Planned downtime is considered as uptime in this instance; hence, the term adjusted availability.

Downtime

The duration during which the host was out of run level 3 is considered as downtime (that is, the difference in coordinated universal time (UTC) between the outage event and its corresponding boot event). Downtime is recorded as a part of the outage event (panic/halt). It is decided by the wasPlanned field. wasPlanned can be one of the following designations:

  • Undefined (value of 0)

  • Planned (value of 1)

  • Unplanned (value of 2)

In the sample datagram (above), event #2 is a panic event, and event #3 is its corresponding boot event; the difference in UTC of event #3 and event #2 is the downtime. Therefore, downtime = 1207861340 - 1207861339 (= 1 sec)

Since the wasPlanned flag is 2, the downtime is marked against the field dwnUnplnd (Unplanned downtime)

Total availability

Represented in percentage as: (Total uptime/Total elapsed time) * 100

Types of Events

The following types of events are recorded in the Availability datagram by the Oracle Lightweight Availability Collection Tool:

  • epoch

    Marks the beginning of event tracking. It is recorded only once in the Availability datagram (at the inception). The UTC of this event marks the inception time of the Oracle Lightweight Availability Collection Tool on the monitored host.

  • boot

    Whenever the host returns to run level 3, a boot event is recorded in the datagram along with the corresponding timestamp.

  • halt

    Whenever the host leaves run level 3 to any other level, a halt event is created with the time of halt being the time the host left run level 3.

  • panic

    If the host encounters an un-natural downing such as system crash, upon the subsequent boot of the host (that is, a return to run level 3), a panic event is recorded where the time of the panic event is the time at which the Oracle Lightweight Availability Collection Tool stopped running.

  • time

    Indicates the last recorded UTC for offline reporting. This event contains the consolidated uptime and downtime information. It also reports the elapsed time (measured as the duration in UTC that the Oracle Lightweight Availability Collection Tool is monitoring this host since inception). Apart from this information, the time event also reports system availability in two forms: Total availability and Adjusted availability.

Uptime

The difference in UTC between the current outage event and the last event before it, which would be a boot event, is measured as uptime.

In the sample datagram (above), if the uptime field in event #1 (boot event) is calculated as the difference in UTC between event #3 and event #2uptime = 1207861339 - 1207784519 (= 76820 secs)