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Memory Checks
Memory checks vary depending on the following factors:
- Memory Free - Percentage
- Memory Free - Specific Value
- Memory Used - Percentage
- Memory Used - Specific Value
It is common for memory checks to be a combination of physical memory + swap/page. If the check supports checking the physical memory separately then an example will be provided for that as well.
The sections below provide examples of how to perform these checks using different methods.
Memory Free - Percentage
These are memory free checks based on percentages, they are best used when you want to be notified if the amount of free memory is running out.
Nagios Plugins
Nagios Plugins does not include a memory plugin however the linux-nrpe-agent does provide custom_check_mem. The thresholds for the plugin are triggered if the free memory is less than the supplied value.
| Unit: | % |
| Warning: | 20% Free |
| Critical: | 10% Free |
Command:
./custom_check_mem -w 20 -c 10
Output:
OK - 1517 / 1893 MB (80%) Free Memory, Used: 375 MB, Shared: 0 MB, Buffers: 122 MB, Cached: 189 MB | total=1893MB free=1517MB used=375MB shared=0MB buffers=122MB cached=189MB
If you do not want the cached memory to be part of the thresholds calculations the -n argument is used:
Command:
./custom_check_mem -w 20 -c 10 -n
Output:
OK - 1706 / 1893 MB (90%) Free Memory, Used: 375 MB, Shared: 0 MB, Buffers: 122 MB, Cached: 189 MB | total=1893MB free=1706MB used=375MB shared=0MB buffers=122MB cached=189MB
NCPA
NPCA includes a memory module however it only reports on used memory for percentages, please see the Memory Used - Percentage section.
If you wanted a free memory check then you will need to specify a value as demonstrated in the Memory Free - Specific Value section.
NSClient++ via check_nt
NSClient++ includes a memory module. The checks only support percentage values for used memory.
NSClient++ via check_nrpe
NSClient++ includes a memory module. The thresholds for the memory checks are triggered if the free memory is less than the supplied value.
| Unit: | % |
| Warning: | 20% Free |
| Critical: | 10% Free |
Command:
./check_nrpe -H 10.25.14.10 -c check_memory -a 'warn=free<20%' 'crit=free<10%'
Output:
OK: committed = 2.314GB, physical = 2.089GB|'committed'=4.68562GB;1.39991;0.69995;0;6.99956 'committed %'=66%;19;9;0;100 'physical'=3.91086GB;1.19991;0.59995;0;5.99956 'physical %'=65%;19;9;0;100
To only check the physical memory the type= argument can be used:
Command:
./check_nrpe -H 10.25.14.10 -c check_memory -a type=physical 'warn=free<20%' 'crit=free<10%'
Output:
OK: physical = 2.101GB|'physical'=3.89902GB;1.19991;0.59995;0;5.99956 'physical %'=64%;19;9;0;100
WMI
Check WMI Plus includes a memory module. Using the Nagios Plugin Threshold standards, the thresholds are triggered if the free memory is less than the supplied value.
| Unit: | % |
| Warning: | 20% Free |
| Critical: | 10% Free |
Command:
./check_wmi_plus.pl -H 10.25.14.3 -u wmiagent -p Str0ngP@ssw0rd -m checkmem -w '_MemFree%=20:' -c '_MemFree%=10:'
Output:
OK - Physical Memory: Total: 1,023.492MB - Used: 483.531MB (47%) - Free: 539.961MB (53%)|'Physical Memory Used'=507019264Bytes; 'Physical Memory Utilisation'=47%;
SNMP
The check_snmp_storage_wizard.pl plugin allows you to target physical memory using SNMP and regular expressions. The thresholds for the memory checks are triggered if the free memory is less than the supplied value.
| Unit: | % |
| Warning: | 10% Free |
| Critical: | 5% Free |
Command:
./check_snmp_storage_wizard.pl -H 10.25.13.15 -C public --v2c -m "Physical" -T pl -w 10 -c 5 -f
Output:
Physical memory: 79%left(1450MB/1840MB) (>10%) : OK | 'Physical_memory'=390MB;1656;1748;0;1840
Memory Free - Specific Value
These are memory free checks based on specific values, they are best used when you want to be notified if the amount of free memory is running out.
Nagios Plugins
Nagios Plugins does not include a memory plugin however the linux-nrpe-agent does provide custom_check_mem. The checks only support percentage values for free memory.
NCPA
NPCA includes a memory module. Using the Nagios Plugin Threshold standards, the thresholds are triggered if the free memory is less than the supplied value.
| Unit: | GB |
| Warning: | 4GB Free |
| Critical: | 2GB Free |
Command:
./check_ncpa.py -H 10.25.254.50 -t Str0ngT0k3n -M memory/virtual/free -u G -w 4: -c 2:
Output:
OK: Free was 10.66 GB | 'free'=10.66GB;4:;2:;
NSClient++ via check_nt
NSClient++ includes a memory module. The checks only support percentage values for used memory.
NSClient++ via check_nrpe
NSClient++ includes a memory module. The thresholds for the memory checks are triggered if the free memory is less than the supplied value.
| Unit: | GB |
| Warning: | 4GB Free |
| Critical: | 2GB Free |
Command:
./check_nrpe -H 10.25.14.10 -c check_memory -a 'warn=free<4G' 'crit=free<2G'
Output:
WARNING: committed = 2.315GB, physical = 2.092GB|'committed'=4.68453GB;4;2;0;6.99956 'committed %'=66%;57;28;0;100 'physical'=3.90794GB;4;2;0;5.99956 'physical %'=65%;66;33;0;100
To only check the physical memory the type= argument can be used:
Command:
./check_nrpe -H 10.25.14.10 -c check_memory -a type=physical 'warn=free<4G' 'crit=free<2G'
Output:
WARNING: physical = 2.217GB|'physical'=3.78282GB;4;2;0;5.99956 'physical %'=63%;66;33;0;100
WMI
Check WMI Plus includes a memory module. Using the Nagios Plugin Threshold standards, the thresholds are triggered if the free memory is less than the supplied value.
| Unit: | GB |
| Warning: | 4GB Free (must be expressed as 4000000000 bytes) |
| Critical: | 2GB Free (must be expressed as 2000000000 bytes) |
Command:
./check_wmi_plus.pl -H 10.25.14.3 -u wmiagent -p Str0ngP@ssw0rd -m checkmem -w '_MemFree=4000000000:' -c '_MemFree=2000000000:'
Output:
CRITICAL - [Triggered by _MemFree<2000000000] - Physical Memory: Total: 1,023.492MB - Used: 483.527MB (47%) - Free: 539.965MB (53%)|'Physical Memory Used'=507015168Bytes; 'Physical Memory Utilisation'=47%;
SNMP
The check_snmp_storage_wizard.pl plugin allows you to target physical memory using SNMP and regular expressions. The thresholds for the memory checks are triggered if the free memory is less than the supplied value.
| Unit: | MB |
| Warning: | 4GB Free (must be expressed as 4000 MB) |
| Critical: | 2GB Free (must be expressed as 2000 MB) |
Command:
./check_snmp_storage_wizard.pl -H 10.25.13.15 -C public --v2c -m "Physical" -T bl -w 4000 -c 2000 -f
Output:
Physical memory: 1450MBleft/1840MB (79%) (<2000MB) : CRITICAL | 'Physical_memory'=390MB;-2160;-160;0;1840
Memory Used - Percentage
These are memory usage checks based on percentages, they are best used when you want to be notified if the amount of used memory exceeds a threshold.
Nagios Plugins
The check_disk plugin is part of Nagios Plugins. Checks on Percentage Used are not possible with the plugin, you will need to perform a memory free check instead.
NCPA
NPCA includes a memory module. The thresholds are triggered if the used memory is greater than the supplied value.
| Unit: | % |
| Warning: | 90% Used |
| Critical: | 95% Used |
Command:
./check_ncpa.py -H 10.25.254.50 -t Str0ngT0k3n -M memory/virtual/percent -w 90 -c 95
Output:
OK: Percent was 25.20 % | 'percent'=25.20%;90;95;
NSClient++ via check_nt
NSClient++ includes a memory module. The thresholds for the memory checks are triggered if the used memory is greater than the supplied value.
| Unit: | % |
| Warning: | 90% Used |
| Critical: | 95% Used |
Command:
./check_nt -H 10.25.14.10 -p 12489 -s 'Str0ngP@ssw0rd' -v MEMUSE -w 90 -c 95
Output:
Memory usage: total:7167.61 MB - used: 2372.04 MB (33%) - free: 4795.58 MB (67%) | 'Memory usage'=2372.04MB;6450.85;6809.23;0.00;7167.61
NSClient++ via check_nrpe
NSClient++ includes a memory module. The thresholds for the memory checks are triggered if the used memory is greater than the supplied value.
| Unit: | % |
| Warning: | 90% Used |
| Critical: | 95% Used |
Command:
./check_nrpe -H 10.25.14.10 -c check_memory -a 'warn=used>90%' 'crit=used>95%'
Output:
OK: committed = 2.391GB, physical = 2.21GB|'committed'=2.39108GB;6.2996;6.64958;0;6.99956 'committed %'=34%;89;94;0;100 'physical'=2.21012GB;5.3996;5.69958;0;5.99956 'physical %'=36%;89;94;0;100
To only check the physical memory the type= argument can be used:
Command:
./check_nrpe -H 10.25.14.10 -c check_memory -a type=physical 'warn=used>90%' 'crit=used>95%'
Output:
OK: physical = 2.211GB|'physical'=2.21104GB;5.3996;5.69958;0;5.99956 'physical %'=36%;89;94;0;100
WMI
Check WMI Plus includes a memory module. The thresholds are triggered if the used memory is greater than the supplied value.
| Unit: | % |
| Warning: | 90% Used |
| Critical: | 95% Used |
Command:
./check_wmi_plus.pl -H 10.25.14.3 -u wmiagent -p Str0ngP@ssw0rd -m checkmem -w '_MemUsed%=90' -c '_MemUsed%=95'
Output:
OK - Physical Memory: Total: 1,023.492MB - Used: 484.043MB (47%) - Free: 539.449MB (53%)|'Physical Memory Used'=507555840Bytes; 'Physical Memory Utilisation'=47%;90;95;
SNMP
The check_snmp_storage_wizard.pl plugin allows you to target physical memory using SNMP and regular expressions. The thresholds for the memory checks are triggered if the used memory is greater than the supplied value.
| Unit: | % |
| Warning: | 90% Used |
| Critical: | 95% Used |
Command:
./check_snmp_storage_wizard.pl -H 10.25.13.15 -C public --v2c -m "Physical" -T pu -w 90 -c 95 -f
Output:
Physical memory: 21%used(390MB/1840MB) (<90%) : OK | 'Physical_memory'=390MB;1656;1748;0;1840
Memory Used - Specific Value
These are memory usage checks based on a specific value, they are best used when you want to be notified if the amount of used memory exceeds a threshold.
Nagios Plugins
The check_disk plugin is part of Nagios Plugins. Checks on Used amount are not possible with the plugin, you will need to perform a memory free check instead.
NCPA
NPCA includes a memory module. The thresholds are triggered if the used memory is greater than the supplied value.
| Unit: | GB |
| Warning: | 8GB Used |
| Critical: | 16GB Used |
Command:
./check_ncpa.py -H 10.25.254.50 -t Str0ngT0k3n -M memory/virtual/used -u G -w 8 -c 16
Output:
OK: Used was 3.25 GB | 'used'=3.25GB;8;16;
NSClient++ via check_nt
NSClient++ includes a memory module. The checks only support percentage values for used memory space.
NSClient++ via check_nrpe
NSClient++ includes a memory module. The thresholds for the memory checks are triggered if the used memory is greater than the supplied value.
| Unit: | GB |
| Warning: | 8GB Used |
| Critical: | 16GB Used |
Command:
./check_nrpe -H 10.25.14.10 -c check_memory -a 'warn=used>8G' 'crit=used>16G'
Output:
OK: committed = 2.39GB, physical = 2.211GB|'committed'=2.38975GB;8;16;0;6.99956 'committed %'=34%;114;228;0;100 'physical'=2.21126GB;8;16;0;5.99956 'physical %'=36%;133;266;0;100
To only check the physical memory the type= argument can be used:
Command:
./check_nrpe -H 10.25.14.10 -c check_memory -a type=physical 'warn=used>8G' 'crit=used>16G'
Output:
OK: physical = 2.211GB|'physical'=2.21138GB;8;16;0;5.99956 'physical %'=36%;133;266;0;100
WMI
Check WMI Plus includes a memory module. The thresholds are triggered if the used memory is greater than the supplied value.
| Unit: | GB |
| Warning: | 8GB Used (must be expressed as 8000000000 bytes) |
| Critical: | 16GB Used (must be expressed as 16000000000 bytes) |
Command:
./check_wmi_plus.pl -H 10.25.14.3 -u wmiagent -p Str0ngP@ssw0rd -m checkmem -w '_MemUsed=8000000000' -c '_MemUsed=16000000000'
Output:
OK - Physical Memory: Total: 1,023.492MB - Used: 484.129MB (47%) - Free: 539.363MB (53%)|'Physical Memory Used'=507645952Bytes;8000000000;16000000000; 'Physical Memory Utilisation'=47%;
SNMP
The check_snmp_storage_wizard.pl plugin allows you to target physical memory using SNMP and regular expressions. The thresholds for the memory checks are triggered if the used memory is greater than the supplied value.
| Unit: | MB |
| Warning: | 8GB Used (must be expressed as 8000 MB) |
| Critical: | 16GB Used (must be expressed as 16000 MB) |
Command:
./check_snmp_storage_wizard.pl -H 10.25.13.15 -C public --v2c -m "Physical" -T bu -w 8000 -c 16000 -f
Output:
Physical memory: 390MBused/1840MB (21%) (<8000MB) : OK | 'Physical_memory'=390MB;8000;16000;0;1840
Final Thoughts
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