IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

288 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

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Average:4 57 0.64 0.67

05:00:01 PM DEV tps blks/s

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Average:dev3-0 0.87 96.40

Average:dev8-0 10.01 406.08

8.3.7 isag

The output of sar is straight text and can be very time consuming to process. Instead, the

isag command (Interactive System Activity Grapher) can show the data gathered by sar in a

graphical format (see Figure 8-5).

Figure 8-5 Paging statistics

When you start isag you must first select a data source. Click the - button to the right of data

source. A menu will appear showing the different data sources available. The data sources

are named sa01, sa02, sa03, etc., each standing for a day of the month when recorded (for

example, sa11 would mean the log file recorded on the 11th day of the current month).

However, only the last nine days are available for analysis.

The slider on the left of the window (see Figure 8-5) is used to adjust the vertical scale of the

graph. By default, isag will display the paging statistics, but you can change the view by

clicking Chart and then choosing the data you are interested in:

򐂰 I/O transfer rate

򐂰 Paging statistics

򐂰 Process creation

򐂰 Run queue

򐂰 Memory and swap

򐂰 Memory activities

򐂰 CPU utilization

򐂰 node status

򐂰 System switching

򐂰 System swapping

Chapter 8. Open system servers - Linux for xSeries 289

Paging statistics

Paging statistics has the following counters:

pgpgin/s Total number of blocks the system paged in from disk per second

pgpgout/s Total number of blocks the system paged out to disk per second

activepg Number of active (recently touched) pages in memory

inadtypg Number of inactive dirty (modified or potentially modified) pages in

memory

inaclnpg Number of inactive clean (not modified) pages in memory

I/O transfer rate

I/O transfer rate has the following counters:

rtps Total number of read requests issued to physical disk.

wtps Total number of write requests issued to physical disk.

bread/s Total amount of data read from the drive in blocks per second. A block

is of indeterminate size.

bwrtn/s Total amount of data written to the drive in blocks per second.

Figure 8-6 illustrates a sample I/O transfer rate graphic report.

Figure 8-6 I/O transfer rate report

Run Queue

Run Queue has the following counters:

runq-sz Run queue length (number of processes waiting for runtime)

plist-sz Number of processes in the process list

Note: isag keeps data for only one week. After one week, the collected data for the

seventh day will be deleted. This might not be enough to do a proper bottleneck analysis or

to make a trend analysis of the server.

290 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

ldavg-1 System load average for the last minute

ldavg-5 System load average for the last five minutes

Figure 8-7 illustrates a sample Run Queue graphic report.

Figure 8-7 Run Queue report

Memory and Swap

Memory and Swap has the following counters:

kbmemfree Amount of free memory in KB

kbmemused Amount of used memory in KB (without memory used by the kernel)

kbmemshrd Amount of memory shared by the system in KB (always 0 with kernel

2.4)

kbbuffers Amount of memory used as buffers

kbcached Amount of memory used for caching

kbswpfree Amount of free swap space

kbswpused Amount of used swap space

Figure 8-8 on page 291 illustrates a sample Memory and Swap graphic report.

Chapter 8. Open system servers - Linux for xSeries 291

Figure 8-8 Memory and Swap report

Memory Activities

Memory Activities has the following counters:

frmpg/s Number of memory pages freed by the system per second. (A

negative value represents the number of pages allocated by the

system.)

shmpg/s Number of additional memory pages shared by the system per

second. A negative value means fewer pages shared by the system.

bufpg/s Number of additional memory pages used as buffers by the system

per second. A negative value means fewer pages used as buffers by

the system.

camp/s Number of additional memory pages cached by the system per

second. A negative value means fewer pages in the cache.

Figure 8-9 on page 292 illustrates a sample Memory Activities graphic report.

292 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

Figure 8-9 Memory Activities report

CPU Utilization

CPU Utilization has the following counters:

%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 nice priority

%system Percentage of CPU utilization that occurred while executing at the

system level (kernel)

Figure 8-10 on page 293 illustrates a sample CPU Utilization graphic report.