Net-SNMP
Net-SNMP is the F/OSS SNMP agent for POSIX-compatible systems.
Webpage:
Monitoring CPU Usage
Monitoring Memory Usage
Monitoring Network Interface Traffic
Monitoring File System Capacity
Monitoring Processes
Monitoring Uptime
Monitoring TCP/UDP (L4) Sockets
Monitoring Disk I/O Activity
Fixed Disk Storage Device usage access statistics are provided by the UCD-DISKIO-MIB as implemented by the Net-SNMP agent. There is a convenient table in the MIB that maps the I/O operations, bytes read/written, and average load from each device probed by the kernel: UCD-DISKIO-MIB::diskioTable
Example output:
system% snmptable -v2c -c [string] localhost diskIOTable
SNMP table: UCD-DISKIO-MIB::diskIOTable
diskIOIndex diskIODevice diskIONRead diskIONWritten diskIOReads diskIOWrites diskIOLA1 diskIOLA5 diskIOLA15 diskIONReadX diskIONWrittenX
1 da0 93798944 2122439680 1481216 11776749 1 1 1 34453537312 268410412032
2 da1 52808736 2122439680 1481217 11776749 1 1 1 34412547104 268410412032
* Time-metered load averages for the last 1, 5, or 15 minutes are represented in UCD-DISKIO-MIB by diskIOLA[1|5|15](if your agent supports them):
The [1|5|15] minute average load of disk (%)"
* diskION[Read|Written] is defined in the MIB as:
The number of bytes read/writen from/to this device since boot.
Note: diskIONReadX|diskIONWrittenX provide Counter64 versions
* diskIO[Writes|Reads] identifies operations, not bytes:
The number of write/read accesses to this device since boot.
Note: diskIOwrites numbers provide a read-operations count, which, depending on how the Net-SNMP agent code for the UCD-DISKIO-MIB is implemented in your operating system, is likely the number of read()/write() calls from the VFS layer to the device driver within the kernel. Each read operation will result in a byte count from the device sector size identified in (256/512/1024/2048/4096-byte allocation units per HOST-RESOURCES-MIB::hrStorageTable)
Example:
$ snmptable -v2c -c [community] localhost hrStorageTable
SNMP table: HOST-RESOURCES-MIB::hrStorageTable
hrStorageIndex hrStorageType hrStorageDescr hrStorageAllocationUnits hrStorageSize hrStorageUsed hrStorageAllocationFailures
1 HOST-RESOURCES-TYPES::hrStorageOther Memory Buffers 256 Bytes 0 178772 0
2 HOST-RESOURCES-TYPES::hrStorageRam Real Memory 4096 Bytes 198876 38467 0
3 HOST-RESOURCES-TYPES::hrStorageVirtualMemory Swap Space 4096 Bytes 524256 19580 0
4 HOST-RESOURCES-TYPES::hrStorageOther Memory Buffer Clusters 1024 Bytes 25600 -184744 0
5 HOST-RESOURCES-TYPES::hrStorageFixedDisk / 2048 Bytes 506487 30268 0
6 HOST-RESOURCES-TYPES::hrStorageFixedDisk /dev 512 Bytes 2 2 0
7 HOST-RESOURCES-TYPES::hrStorageFixedDisk /opt 2048 Bytes 56734705
Graphing the Data in MRTG:
* Average Load
Unlike most I/O OIDs, this is an Integer/Counter-type data that you would graph like CPU Usage:
diskIOLA1 OBJECT-TYPE
SYNTAX Integer32 (0..100)
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The 1 minute average load of disk (%)"
::= { diskIOEntry 9 }
* I/O Operations
This data is stored in the MIB as a Counter32 variable. You can graph non-linear growth overall to observe patterns (which will reset when the integer overlaps at 232) or you can graph "usage" by letting MRTG calculate bytes/second using the "non-gauge" method.
Examples of both are seen below.
To ensure that MRTG can reference individuals cells of the table, ensure that MRTG parses the MIB file for UCD-DISKIO-MIB on your system:
LoadMIBs: /usr/local/share/snmp/mibs/UCD-DISKIO-MIB.txt [...snip...] PageTop[hostname.diskio.bytes]:Bytes Read/Written gm0
ShortLegend[hostname.diskio.bytes]: Bytes: YLegend[hostname.diskio.bytes]: Bytes: LegendI[hostname.diskio.bytes]: Bytes Read: LegendO[hostname.diskio.bytes]: Bytes Written: Legend1[hostname.diskio.bytes]: Bytes Read: Legend2[hostname.diskio.bytes]: Bytes Written: Target[hostname.diskio.bytestotal]: diskIONRead.1&diskIONWritten.1:community@hostname Maxbytes[hostname.diskio.bytestotal]: 4294967295 Options[hostname.diskio.bytestotal]: nopercent,gauge,growright Title[hostname.diskio.bytestotal]: Bytes Read/Written gm0 total PageTop[hostname.diskio.bytestotal]:Bytes Read/Written gm0 total
ShortLegend[hostname.diskio.bytestotal]: Bytes: YLegend[hostname.diskio.bytestotal]: Bytes: LegendI[hostname.diskio.bytestotal]: Bytes Read: LegendO[hostname.diskio.bytestotal]: Bytes Written: Legend1[hostname.diskio.bytestotal]: Bytes Read: Legend2[hostname.diskio.bytestotal]: Bytes Written: kMG[hostname.diskio.bytestotal]: k,M,G,T,P,X
Screenshot:
And to graph I/O operations (both "usage" and "total"):
Target[system.diskio.rw]: diskIOWrites.1&diskIOReads.1:community@system Maxbytes[system.diskio.rw]: 1000000000 Options[system.diskio.rw]: nopercent,growright Title[system.diskio.rw]: Read/Write I/O ops gm0 (not bytes) PageTop[system.diskio.rw]:Reads/Write I/O ops gm0 (not bytes)
ShortLegend[system.diskio.rw]: IOs: YLegend[system.diskio.rw]: IOs: LegendI[system.diskio.rw]: Writes LegendO[system.diskio.rw]: Reads Legend1[system.diskio.rw]: Writes Legend2[system.diskio.rw]: Reads Target[system.diskio.rwtotal]: diskIOWrites.1&diskIOReads.1:community@system Maxbytes[system.diskio.rwtotal]: 10000000000 Options[system.diskio.rwtotal]: nopercent,gauge,growright Title[system.diskio.rwtotal]: Reads/Write I/O ops gm0 total (not bytes) PageTop[system.diskio.rwtotal]:Reads/Write I/O ops gm0 total (not bytes)
ShortLegend[system.diskio.rwtotal]: IOs: YLegend[system.diskio.rwtotal]: IOs: LegendI[system.diskio.rwtotal]: Writes LegendO[system.diskio.rwtotal]: Reads Legend1[system.diskio.rwtotal]: Writes Legend2[system.diskio.rwtotal]: Reads kMG[system.diskio.rwtotal]: k,M,G,T,P,X
And associated screenshot:
This section was contributed by Brian A. Seklecki