UCD-DISKIO-MIB

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Organization: University of California, Davis

Last Updated: 2016-04-04

Category: Net-SNMP and Linux

Description: Defines managed objects for monitoring disk I/O statistics on Net-SNMP agents, including per-device read/write byte counts and operation counters.

IPNetwork Monitor uses several OIDs from this MIB in network discovery and polling the applicable devices. Start monitoring UCD-DISKIO-MIB with a free 30-day trial of IPNetwork Monitor.

What Is UCD-DISKIO-MIB?

UCD-DISKIO-MIB is a Net-SNMP (formerly UCD-SNMP) extension MIB that exposes disk I/O statistics gathered by the Net-SNMP agent running on Unix-like hosts. It provides a table of per-device disk metrics including bytes read/written, read/write operation counts, and system load-average figures. This MIB is squarely aimed at monitoring software/OS-level performance status of a server rather than physical hardware health directly, giving visibility into disk throughput and system load that can signal I/O bottlenecks or overloaded storage subsystems. It depends on the Net-SNMP agent's disk I/O data source (typically /proc/diskstats or platform equivalents) rather than any other standard MIB. It is commonly deployed on Linux/Unix servers running the Net-SNMP daemon (snmpd) for general-purpose performance and capacity monitoring in data centers, where administrators often search for the ucd-diskio-mib documentation to interpret its disk I/O counters correctly.

IPNetwork Monitor allows you to monitor SNMP objects defined in UCD-DISKIO-MIB. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

Supported Devices

Linux/Unix server running Net-SNMP agent

Monitoring Examples

An admin would poll diskIOTable, walking diskIOEntry rows indexed by diskIOIndex to get diskIODevice (e.g., sda, sdb) alongside diskIONRead and diskIONWritten (cumulative bytes) and diskIOReads/diskIOWrites (operation counts). Comparing deltas of diskIONReadX (the high-capacity 64-bit read counter) across polling intervals reveals sudden spikes in disk throughput, while diskIOLA1/diskIOLA5/diskIOLA15 show 1/5/15-minute load averages that, combined with rising I/O counters, can flag a disk-bound performance problem. A steadily climbing diskIOWrites count with flat diskIONWritten bytes could also hint at small, inefficient write patterns worth investigating.

What Can Be Monitored

disk read bytes
disk write bytes
disk read operation count
disk write operation count
1/5/15-minute system load average
per-device disk index/name

Imported Objects

From SNMPv2-SMI

Counter32
Counter64
Integer32
MODULE-IDENTITY
OBJECT-TYPE

From SNMPv2-TC

DisplayString

From UCD-SNMP-MIB

ucdExperimental

OBJECT-IDENTITY

How to Use in IPNetwork Monitor

Example using diskIONRead OID:

Select a Linux/Unix server running Net-SNMP agent (per-device disk read/write throughput status) as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and type diskIONRead into the Find box to locate it in the OID tree, selecting the specific row/instance you want to monitor since this is a table column, then select it and click OK. The number of bytes read from this device since boot. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is a Counter32-type OID, Value bounds is the most useful condition here — trigger an alert if the counter increases sharply between polls relative to its normal baseline, since an unexpected spike often reflects a real change in traffic or activity. Click Finish to create the monitor; you can adjust any parameter later.

OIDs

OID symbolic	OID numeric	Type	Access	Description
ucdDiskIOMIB	1.3.6.1.4.1.2021.13.15			This MIB module defines objects for disk IO statistics.
diskIOTable	1.3.6.1.4.1.2021.13.15.1		not-accessible	Table of IO devices and how much data they have read/written.
diskIOEntry	1.3.6.1.4.1.2021.13.15.1.1		not-accessible	An entry containing a device and its statistics.
I32 diskIOIndex	1.3.6.1.4.1.2021.13.15.1.1.1	Integer32	read-only	Reference index for each observed device.
STR diskIODevice	1.3.6.1.4.1.2021.13.15.1.1.2	DisplayString	read-only	The name of the device we are counting/checking.
C32 diskIONReadEx	1.3.6.1.4.1.2021.13.15.1.1.3	Counter32	read-only	The number of bytes read from this device since boot.
C32 diskIONWritten	1.3.6.1.4.1.2021.13.15.1.1.4	Counter32	read-only	The number of bytes written to this device since boot.
C32 diskIOReads	1.3.6.1.4.1.2021.13.15.1.1.5	Counter32	read-only	The number of read accesses from this device since boot.
C32 diskIOWrites	1.3.6.1.4.1.2021.13.15.1.1.6	Counter32	read-only	The number of write accesses to this device since boot.
I32 diskIOLA1	1.3.6.1.4.1.2021.13.15.1.1.9	Integer32	read-only	The 1 minute average load of disk (%)
I32 diskIOLA5	1.3.6.1.4.1.2021.13.15.1.1.10	Integer32	read-only	The 5 minute average load of disk (%)
I32 diskIOLA15	1.3.6.1.4.1.2021.13.15.1.1.11	Integer32	read-only	The 15 minute average load of disk (%)
C64 diskIONReadX	1.3.6.1.4.1.2021.13.15.1.1.12	Counter64	read-only	The number of bytes read from this device since boot.
C64 diskIONWrittenX	1.3.6.1.4.1.2021.13.15.1.1.13	Counter64	read-only	The number of bytes written to this device since boot.
C64 diskIOBusyTime	1.3.6.1.4.1.2021.13.15.1.1.14	Counter64	read-only	The number of usecs the drive has been busy since boot.

RFC description

Part of the University of California Davis (UCD) MIB suite, provides monitoring of disk I/O statistics including read/write operations, bytes transferred, and I/O latency for system disks.

Start monitoring Linux/Unix server running Net-SNMP agent (per-device disk read/write throughput status) with a free 30-day trial of IPNetwork Monitor. Import MIBs, browse SNMP OIDs, create custom SNMP monitors, configure alerts, and monitor any SNMP-enabled network device from a single console.

Download UCD-DISKIO-MIB