NET-SNMP Tutorial -- MRTG
Monitoring CPU load
There are several ways to try to monitor CPU usage, because the system maintains several CPU counters: Idle, System, User, Nice. As MRTG does not allow you to graph more than two values at a time, it is possible to select any two values ang graoh aginst each other, but it it also possible to compute a combined value.
User vs Idle CPU usage
An example of such a graph is here.
The corresponding MRTG configuration is LoadMIBs: /usr/local/share/snmp/mibs/UCD-SNMP-MIB.txt
Target[kontor.cpu]:ssCpuRawUser.0&ssCpuRawIdle.0:public@10.10.11.2
RouterUptime[kontor.cpu]: public@10.10.11.2
MaxBytes[kontor.cpu]: 100
Title[kontor.cpu]: CPU LOAD
PageTop[kontor.cpu]:
User CPU Load %
Unscaled[kontor.cpu]: ymwd
ShortLegend[kontor.cpu]: %
YLegend[kontor.cpu]: CPU Utilization
Legend1[kontor.cpu]: User CPU in % (Load)
Legend2[kontor.cpu]: Idle CPU in % (Load)
Legend3[kontor.cpu]:
Legend4[kontor.cpu]:
LegendI[kontor.cpu]: User
LegendO[kontor.cpu]: Idle
Options[kontor.cpu]: growright,nopercent
User vs System CPU usage
An example of such a graph is here.
The corresponding MRTG configuration is LoadMIBs: /usr/local/share/snmp/mibs/UCD-SNMP-MIB.txt
Target[kontor.usrsys]:ssCpuRawUser.0&ssCpuRawSystem.0:public@10.10.11.2
RouterUptime[kontor.usrsys]: public@10.10.11.2
MaxBytes[kontor.usrsys]: 100
Title[kontor.usrsys]: CPU LOAD
PageTop[kontor.usrsys]:
CPU (user and system) Load %
Unscaled[kontor.usrsys]: ymwd
ShortLegend[kontor.usrsys]: %
YLegend[kontor.usrsys]: CPU Utilization
Legend1[kontor.usrsys]: User CPU in % (Load)
Legend2[kontor.usrsys]: System CPU in % (Load)
Legend3[kontor.usrsys]:
Legend4[kontor.usrsys]:
LegendI[kontor.usrsys]: User
LegendO[kontor.usrsys]: System
Options[kontor.usrsys]: growright,nopercent
Active CPU usage
An example of such a graph is here. This example sums User, System and Nice and plots it as a single value.
The corresponding MRTG configuration is LoadMIBs: /usr/local/share/snmp/mibs/UCD-SNMP-MIB.txt
Target[kontor.cpusum]:ssCpuRawUser.0&ssCpuRawUser.0:public@10.10.11.2 + ssCpuRawSystem.0&ssCpuRawSystem.0:public@10.10.11.2 + ssCpuRawNice.0&ssCpuRawNice.0:public@10.10.11.2
RouterUptime[kontor.cpusum]: public@10.10.11.2
MaxBytes[kontor.cpusum]: 100
Title[kontor.cpusum]: CPU LOAD
PageTop[kontor.cpusum]:
Active CPU Load %
Unscaled[kontor.cpusum]: ymwd
ShortLegend[kontor.cpusum]: %
YLegend[kontor.cpusum]: CPU Utilization
Legend1[kontor.cpusum]: Active CPU in % (Load)
Legend2[kontor.cpusum]:
Legend3[kontor.cpusum]:
Legend4[kontor.cpusum]:
LegendI[kontor.cpusum]: Active
LegendO[kontor.cpusum]:
Options[kontor.cpusum]: growright,nopercent
Monitoring DISK space
There are two tables that can be used when monitoring disk space, UCD-SNMP-MIB:dskTable and HOST-RESOURCES-MIB:hrStorageTable. There are two noticeable differences bwtween these tables: UCD-SNMP-MIB:dskTable requires a configuration directive in snmpd.conf, but it also gives a direct measure of the percentage of free space
On the system I used for these examples, I have the following disks: $ df
Filesystem Size Used Avail Use% Mounted on
/dev/hda6 289M 56M 218M 21% /
/dev/hda1 7.3G 3.2G 4.1G 44% /mnt/windows
/dev/hda7 1.7G 1.2G 429M 74% /usr
/dev/hdc1 19G 6.7G 11G 37% /space
and I have put the following lines into snmpd.conf: disk / 100000
disk /usr 100000
disk /space 100000
Monitoring from dskTable
I used the direct percentage of disk full for the root and /usr partitions in this example It plot the usage of the root and the /usr partitions in one graph. LoadMIBs: /usr/local/share/snmp/mibs/UCD-SNMP-MIB.txt
Target[kontor.root]:dskPercent.1&dskPercent.2:public@10.10.11.2
RouterUptime[kontor.root]: public@10.10.11.2
MaxBytes[kontor.root]: 100
Title[kontor.root]: DISK USAGE
PageTop[kontor.root]:
DISK / and /usr Usage %
Unscaled[kontor.root]: ymwd
ShortLegend[kontor.root]: %
YLegend[kontor.root]: DISK Utilization
Legend1[kontor.root]: Root disk
Legend2[kontor.root]: /usr disk
Legend3[kontor.root]:
Legend4[kontor.root]:
LegendI[kontor.root]: Root disk
LegendO[kontor.root]: /usr disk
Options[kontor.root]: growright,gauge,nopercent
Monitoring from hrStorageTable
Use of hrStorageTable requires no preceding configuration, as in this example It plot the partition size as one value, and the used space as another. Note:the values returned here are in units of hrStorageUnits, which, dependent on the file system type, may or may not be 1K. LoadMIBs: /usr/local/share/snmp/mibs/HOST-RESOURCES-MIB.txt
Target[kontor.hrroot]:hrStorageSize.1&hrStorageUsed.1:public@10.10.11.2
RouterUptime[kontor.hrroot]: public@10.10.11.2
MaxBytes[kontor.hrroot]: 300000
Title[kontor.hrroot]: DISK / USAGE
PageTop[kontor.hrroot]:
DISK / Usage
ShortLegend[kontor.hrroot]: B
kMG[kontor.hrroot]: k,M,G,T,P
kilo[kontor.hrroot]: 1024
YLegend[kontor.hrroot]: DISK / Utilization
Legend1[kontor.hrroot]: Root disk size
Legend2[kontor.hrroot]: Root disk usage
Legend3[kontor.hrroot]:
Legend4[kontor.hrroot]:
LegendI[kontor.hrroot]: Root disk size
LegendO[kontor.hrroot]: Root disk usage
Options[kontor.hrroot]: growright,gauge,nopercent
Two further examples that have been offered:
Monitoring TCP connections
Target[tcpopen]:
.1.3.6.1.2.1.6.9.0&.1.3.6.1.2.1.6.9.0:public@localhost
Options[tcpopen]: nopercent,growright,gauge,noinfo
Title[tcpopen]: Open TCP connections
PageTop[tcpopen]: Open TCP connections
MaxBytes[tcpopen]: 1000000
YLegend[tcpopen]: # conns
ShortLegend[tcpopen]: connections
LegendI[tcpopen]: Connections:
LegendO[tcpopen]:
Legend1[tcpopen]: Open TCP connections
and
Monitoring Free Memory
Target[freemem]:
.1.3.6.1.4.1.2021.4.11.0&.1.3.6.1.4.1.2021.4.11.0:public@localhost
Options[freemem]: nopercent,growright,gauge,noinfo
Title[freemem]: Free Memory
PageTop[freemem]: Free Memory
MaxBytes[freemem]: 1000000
kMG[freemem]: k,M,G,T,P,X
YLegend[freemem]: bytes
ShortLegend[freemem]: bytes
LegendI[freemem]: Free Memory:
LegendO[freemem]:
Legend1[freemem]: Free memory, not including swap, in bytes
The complete picture
