(Fedora: Lesson 13)

{ Setting up SAR (System Activity Reporting) }

• What is SAR? 
  • SAR is the system activity reporter.
  • By interpreting the reports that sar produces, you can locate system bottlenecks and suggest some possible solutions to those annoying performance problems.
  • The Linux kernel maintains internal counters that keep track of requests, completion times, I/O block counts, etc.
  • From this and other information, sar calculates rates and ratios that give insight into where the bottlenecks are occurring.

   

1. Play virtual machine. (See Below)
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1. Login As student
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2. Start Up A Terminal.
   • Applications --> System Tools --> Terminal
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3. Switch User to root
   • Command: su - root
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4. Determine IP Address and Network Connection.
   • Command: ifconfig -a
   • Note: In my case, the IP Address is 192.168.1.112.
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1. Install the SAR package called sysstat
   • Command: yum install sysstat
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2. Install sysstat's rpm
   • Command: Type "y", and hit enter
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3. Verify Installation Results
   • Note: Just take note of what is getting installed along with the completion notice.
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1. Initialize SAR
   • Command: /usr/lib/sa/sa1 1 1
   • Note:
     • sa1 - Collect and store binary data in the system activity daily data file.
     • The sa1 command collects and store binary data in the /var/log/sa/sadd file, where the dd parameter
       indicates the current day.
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2. Initialize SAR
   • Command: /usr/lib/sa/sa2 -A
   • Note:
     • sa2 - Write a daily report in the /var/log/sa directory.
     • The sa2 command is a shell procedure variant of the sar command which writes a daily report in the
       /var/log/sa/sardd file, where the dd parameter indicates the current day. The sa2 command handles all of the
       flags and parameters of the sar command.
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3. Verify /etc/cron.d/sysstat was created.
   • Command: cat /etc/cron.d/sysstat
   • Note:
     • The sysstat package create a crontab for sar called sysstat located in /etc/cron.d
     • The first uncommented line (i.e., does not start with a #) tells cron to run sar every 10 minutes.
     • The second uncommented line generates a daily summary for the accumulated sar data.
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4. SAR Log Directory
   • Command:
     1. cd /var/log/sa
     2. ls -lrta
   • Note:
     1. sar20
        • The naming convention is "sar" + "day number"  In my case, today is 11-20-2011.
        • This is an ascii file that contain the daily activity for the particular date.
     2. sa20
        • The naming convention is "sa" + "20".
        • The file  is an data file that contain the daily activity, except in binary format.
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1. Basic SAR command
   • Command: sar
   • Note:
     • Notice that after the first three lines, each new line is added every 10 minutes. 
     • This command is looking at CPU for the following:
       • User
         • Percentage of CPU utilization that occurred while executing at the user level (application).
       • Nice
         • Percentage of CPU utilization that occurred while executing at the user level with the nice priority
       • System
         • Percentage of CPU utilization that occurred while executing at the system level (kernel).
       • IO Wait
         • Percentage of time that the CPU or CPUs where idle during which the system had an outstanding disk I/O request.
       • Steal
         • Percentage of time spent in involuntary wait by the virtual CPU or CPUs while the hypervisor was servicing another virtual processor.
       • Idle
         • Percentage of time that the CPU or CPUs were ideal and the system did not have an outstanding disk I/O request.
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2. Swap Usage
   • Command: sar -W
   • Notes:
     • You can use this command to tell if you are running out of ram.
     • Being swapped out is normal for the Linux kernel, which will swap from time to time.
     • Constant swapping is bad, and generally means you need more Ram.
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3. System Load
   • Command:  sar -q
   • Notes:  sar -q
     • Here we are checking to see if the processes are waiting too long to run on the CPU.
     • Servers that are not doing much, should see something lower that 1.
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4. Report I/O and transfer rate statistics
   • Command: sar -b
   • Notes:
     • tps
       • Total number of transfers per second that were issued to physical devices. A transfer is an I/O
         request to a physical device. Multiple logical requests can be combined into a single I/O request
         to the device. A transfer is of indeterminate size.
     • rtps
       • Total number of read requests per second issued to physical devices.
     • wtps
       • Total number of write requests per second issued to physical devices.
     • bread/s
       • Total amount of data read from the devices in blocks per second. Blocks are equivalent to sectors
         with 2.4 kernels and newer and therefore have a size of 512 bytes. With older kernels, a block is
         of indeterminate size
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5. Real Time CPU Utilization
   • Command: sar -u 2 5
   • Notes: Report CPU utilization for each 2 seconds and display only 5 lines.
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6. Real Time Network Utilization
   • Command: sar -n DEV 2 3
   • Notes: With the DEV keyword, statistics from the network devices are reported. The following values are displayed:
     • IFACE
       • Name of the network interface for which statistics are reported.
     • rxpck/s
       • Total number of packets received per second.
     • txpck/s
       • Total number of packets transmitted per second.
     • rxkB/s
       • Total number of kilobytes received per second.
     • txkB/s
       • Total number of kilobytes transmitted per second.
     • rxcmp/s
       • Number of compressed packets received per second (for cslip etc.).
     • txcmp/s
       • Number of compressed packets transmitted per second.
     • rxmcst/s
       • Number of multicast packets received per second.
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7. Real Time Network Utilization
   • Command: sar -n EDEV 2 3
   • Notes: With the EDEV keyword, statistics on failures (errors) from the network devices are reported. The following values are displayed:
     • IFACE
       • Name of the network interface for which statistics are reported.
     • rxerr/s
       • Total number of bad packets received per second.
     • txerr/s
       • Total number of errors that happened per second while transmitting packets.
     • coll/s
       • Number of collisions that happened per second while transmitting packets.
     • rxdrop/s
       • Number of received packets dropped per second because of a lack of space in linux buffers.
     • txdrop/s
       • Number of transmitted packets dropped per second because of a lack of space in linux buffers.
     • txcarr/s
       • Number of carrier-errors that happened per second while transmitting packets.
     • rxfram/s
       • Number of frame alignment errors that happened per second on received packets.
     • rxfifo/s
       • Number of FIFO overrun errors that happened per second on received packets.
     • txfifo/s
       • Number of FIFO overrun errors that happened per second on transmitted packets.
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8. Display data collected by sar in multiple formats.
   • Command: sadf -d /var/log/sa/sa20 -- -B
     • Remember, sa20 will be different in your case.  It will be today's date.
   • Notes:
     • sadf -d extracts data in a format that can be easily ingested by a relational database.
     • Both Excel and Open Office will allow us to specify a semicolon as a field delimiter. Then we can generate our performance report and graph.
   • Proof of Lab:
     • Do a PrtScn, Paste into a word document, Upload to Moodle.
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1. Cut and Paste a screen shot of Section 5, Step 8 into a word document and upload to Moodle.