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Manual: Volume Replicator Advisor 4.1 User's Guide   

Collecting the Sample of Data on AIX

VRAdvisor handles input from several tools for AIX. The tools are listed in order of preference. For example, if you have VERITAS Volume Manager, you should use vxstat to collect data for analysis with VRAdvisor.

On AIX, collect the sample of data using one of the following methods:

Collecting Data Using the vxstat Command

If VxVM is installed on your system, use the vxstat command to collect data for analysis.

  To collect data using vxstat

  1. Set the locale to C:
       # export LC_ALL=C
  2. To collect the data in the format required for analysis, use the following command with exactly the parameters shown:
       # vxstat -g dgname -i interval -c count volumes > filename

    where:

    interval is the data collection interval in seconds.

    count is the number of samples to collect.

    volumes is a list of volume names separated by spaces.

    For example, use the following command to collect a sample of data every 120 seconds and to collect 5040 samples. The volumes are the data volumes hr_dv01 and hr_dv02 in the disk group hrdg. The results are collected in the file vra_in.


       # vxstat -g hrdg -i 120 -c 5040 hr_dv01 hr_dv02 > vra_in

After the data collection completes, the file filename (for example, vra_in) contains the sample of data in the vxstat format, which can be used for analysis by VRAdvisor. To proceed, see Analyzing the Sample of Data.

Collecting Data Using the lvmstat Command

If VxVM is not installed on your system, you can collect data using the lvmstat command and use the script provided with VRAdvisor to convert the output of the lvmstat command into the VRAdvisor format.

  To collect data using lvmstat

  1. Set the locale to C:
       # export LC_ALL=C
  2. Enable stat collection on the volume group using the command:
      # lvmstat -v volgrpname -e
  3. Include a start date at the beginning of the file, because lvmstat does not print the date.
      # date > lvmstat_out.aix
  4. To collect the data in the format required by the conversion script, use the following command with exactly the parameters shown:
      # lvmstat -v volgrpname 120 5040 >> lvmstat_out.aix

    This command tells lvmstat to collect the statistics for all logical volumes in the volume group volgrpname every 120 seconds and to collect 5040 samples. This is seven days' worth of sampling.

The sample of data that you have collected now needs to be converted to a format which can be analyzed with VRAdvisor. Proceed with the following section to run the appropriate conversion script.

Converting the Data to the Required Format

After the data has been collected with the lvmstat command, run the conversion script located in the following directory on the VERITAS software disc containing VRAdvisor:


volume_replicator/tools/vradvisor/scripts/lvmstat2csv_aix.pl

  To convert the lvmstat data for AIX

  1. Ensure that perl is installed on the system on which the script is to be run.
    Note   Note    The script can be run on any system that has perl installed. It does not need to be the same system on which the sar command was run.
  2. To run the script, use the following command:
      # perl lvmstat2csv_aix.pl lvmstat_out.aix interval > vra_in.aix

    where interval is the data collection interval (in seconds) that was used in the lvmstat command to collect the data.

The resulting file, vra_in.aix, contains the sample of data in the VRAdv CSV format, which can be used for analysis by VRAdvisor. To proceed, see Analyzing the Sample of Data.

Collecting Data Using the iostat Command

If VxVM is not installed on your system, you can collect data using the iostat command and use the script provided with VRAdvisor for AIX to convert the output of the iostat command into the VRAdvisor format.


Note   Note    When VRAdvisor calculates the SRL size, it includes the SRL header overhead, which is calculated based on the number of IO operations to volumes. If the sample data is collected using the iostat utility, VRAdvisor uses the number of transfers per second (tps) to calculate the SRL header overhead. Because a transfer can combine multiple logical requests, the number of transfers is smaller than the number of actual logical requests. Consequently, VRAdvisor gives a significantly smaller SRL size than expected. Add 30 percent to the suggested SRL size to get an appropriate SRL size.

  To collect data using iostat

  1. Set the locale to C:
       # export LC_ALL=C
  2. To collect the data in the format required by the conversion script, use the following command with exactly the parameters shown:
      # iostat -T -d interval count > filename

    where:

    interval is the data collection interval in seconds.

    count is the number of samples to collect.

    For example, use the following command to collect the buffer and device activity every 120 seconds and to collect 5040 samples. The results are collected in the file vra_in.


       # iostat -T -d 120 5040 > iostat.out.aix
    Note   Note    The -T option may be omitted if it is not supported in the iostat command. You must then specify the data collection interval when running the conversion script to convert from the iostat format to the VRAdvisor format.

To improve performance, disable the collection of disk input/output statistics on a continuous basis. This causes the first disk report of iostat output to display the message "Disk history since boot not available." instead of disk statistics. The subsequent interval reports generated by the iostat command contain disk statistics collected during the report interval.


Note   Note    If collection of disk input/output statistics is enabled on the system, the first block of statistics displayed by the iostat command will contain cumulative statistics since the system was last booted, and this block needs to be deleted from the file iostat.out.aix before the script is invoked on it.

Converting the Data to the Required Format

After the data has been collected with the iostat command, run the conversion script located in the following directory on the VERITAS software disc containing VRAdvisor:


volume_replicator/tools/vradvisor/scripts/iostat2csv_aix.pl

  To convert the iostat data on AIX

  1. Ensure that perl is installed on the system on which the script is to be run.
    Note   Note    The script can be run on any system that has perl installed. It is not necessary to run the script on the same system on which the iostat command was run.
  2. Run the conversion script. If the -T option was specified in the iostat command when collecting the data, use the following command:
      # perl iostat2csv_aix.pl iostat.out.aix > vra_in.aix

    If the -T option was not specified in the iostat command when collecting the data, then the interval time in seconds must be specified when running the conversion script, as shown below:


      # perl iostat2csv_aix.pl iostat.out.aix 120 > vra_in.aix 

The resulting file, vra_in.aix, contains the sample of data in the VRAdv CSV format, which can be used for analysis by VRAdvisor. To proceed, see Analyzing the Sample of Data.

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Product: Volume Replicator Guides  
Manual: Volume Replicator Advisor 4.1 User's Guide  
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