About SNMP
You can monitor your storage system by implementing the SNMP manager.
SNMP Manager overview
SNMP Manager is installed in the network management station. It collects and manages information from SNMP agents installed in the managed devices on the network.
The SNMP Manager graphically displays information collected from two or more SNMP agents, accumulates the information in the database, and analyzes problems discovered while accumulating this information.
- SNMP versions v1, v2c, and v3 are supported.
- An RFC-compliant encryption algorithm is adopted for User-based Security Model (USM) authentication.
How SNMP works
Simple Network Management Protocol (SNMP) is an industry-standard protocol for managing and monitoring network devices, including disk devices, routers, and hubs. SNMP uses Simple Gateway Management Protocol (SGMP) to manage TCP/IP gateways.
The following figure shows an example SNMP environment.
An SNMP manager monitors the devices, which are referred to as managed nodes. Typically, an SNMP Manager polls the SNMP agents on a periodic basis. The manager receives the reports from the agents and determines whether the devices are operating normally. If an abnormal event occurs, an SNMP Agent can report the condition without a request from the manager, by using a trap message.
When an SNMP manager polls an agent, the following dialogue takes place:
- An SNMP Manager sends a request packet to an SNMP Agent, which requests data regarding the status of the managed node.
- The SNMP Agent sends a response packet back to the SNMP Manager.
- SNMP uses the TCP/IP User Datagram Protocol (UDP). If the SNMP Agent does not respond within a specified time period, the SNMP Manager re-sends the request packet. That time period is set by the system administrator, taking into account the network traffic and operation policy.
- If an SNMP Agent again does not respond to the resent packet, the SNMP Manager assumes that an error has occurred. Depending on the times set for polling and response, this dialogue can take several seconds.
If an SNMP Agent detects an abnormal event, it sends a trap to the SNMP Manager. However, if a trap is dropped in transmission, the SNMP Manager does not know that it was sent. For this reason, you should use both polling and traps to determine whether an abnormal event has occurred.
Management Information Base overview
The standardized configuration and database of network management information is called a Management Information Base (MIB). A standard MIB is common to all SNMP interfaces. An extension MIB is defined by the particular managed device or protocol.
A MIB is a collection of standardized configuration and network management information that is contained in each device on the network. Each MIB contains a set of parameters called managed objects. Each managed object consists of a parameter name, one or more parameters, and a group of operations that can be executed with the object. The MIB defines the type of information that can be obtained from a managed device, and the device settings that can be controlled from a management system.
The MIB definition file, VSPStorageSystemMIB.txt, is located in the program\SNMP folder of the software media kit.
SNMP Agent configuration
The SNMP Agent runs on the storage system.
The SNMP Agent communicates with the SNMP manager through the LAN between the storage system and the SNMP manager.
The following figure illustrates the SNMP environment.
The following figure shows an example of SNMP operations using an SNMP manager.
SNMP Agent overview
The SNMP Agent is mounted on a managed device (such as a hard disk) in the network. It collects error information, the usage condition, and other information about the device, and sends traps to the SNMP Manager.
The SNMP Agent reports disk storage system failures to the manager using the SNMP trap function.
In a storage system, the SNMP Agent is mounted on each CTL. The SNMP Agent on CTL1 or CTL2 normally sends traps. If a failure occurs in either of the CTLs, the SNMP Agent on a normal CTL sends traps. When you use SNMP v3 protocol, you need to register the SNMP Engine ID for each CTL in the SNMP Manager. For details, see Checking SNMP Engine ID.
SNMP traps
An SNMP Agent reports storage system errors to the SNMP Manager using the SNMP trap function.
When an error occurs, the SNMP Agent issues an SNMP trap to the SNMP Manager that includes the product number, nickname, reference code, component where the failure occurred, failure date and time, and detailed information about the failure.
For details about SNMP trap reference codes, see the SIM reference guide.
The following table lists the types of events that trigger an SNMP Agent trap.
|
Events |
Description |
|
Acute failure detected. |
All operations in a storage system stopped. |
|
Serious failure detected. |
Operation in a component where a failure occurred stopped. |
|
Moderate failure detected. |
Partial failure. |
|
Service failure detected. |
Minor failure. |
SNMP Agent operations
Operations that an SNMP Agent can perform fall into the categories GET REQUEST, GETNEXT REQUEST, GETBULK REQUEST, and TRAP.
The following table describes the types of SNMP Agent operations.
|
Operation |
Description |
|
GET REQUEST |
Obtains a specific MIB object value. GET REQUEST is the request from an SNMP Manager, and GET RESPONSE is the agent's response to that request. |
|
GETNEXT REQUEST |
Continuously finds a MIB object. GETNEXT REQUEST is the request from an SNMP Manager, and GET RESPONSE is the agent's response to that request. |
|
GETBULK REQUEST |
Continuously finds specified MIB objects only. GETBULK REQUEST is the request from an SNMP Manager, and GET RESPONSE is the agent's response to that request. |
|
TRAP |
Reports an event (failure) to an SNMP Manager. TRAP occurs without a request from the SNMP Manager. |
SNMP Agent reported errors
Several different types of errors can be reported when GET REQUEST, GETNEXT REQUEST, and GETBULK REQUEST operations are sent to an SNMP Agent.
The following table describes the errors that can be reported and suggests corrective action.
|
Error |
Description |
Corrective action |
|
noError (0) |
Normal |
N/A |
|
noSuchName (2) |
|
Verify that the name of the requested object is correct. |
|
SET REQUEST is received. |
SET REQUEST operation is not supported. | |
|
genErr (5) |
Error occurred for other reasons. |
Retry the operation. |
Component status information from SNMP Manager
You can obtain the status information of certain storage system components from the SNMP Manager.
The following table lists the components for which the status can be obtained.
|
Area |
Component name |
|
Storage System |
Processor(s) |
|
Cache | |
|
Power supplies | |
|
Batteries | |
|
Fans | |
|
Others | |
|
DB |
Power supplies |
|
Environments | |
|
Drives |
The following table lists the status of storage system components, as well as the trap report functions.
|
Status |
Description |
|
Normal |
Normal operation. |
|
Acute failure detected |
All operations in a storage system stopped. |
|
Serious failure detected |
Operation in a component where a failure occurred stopped. |
|
Moderate failure detected |
Partial failure. |
|
Service failure detected |
Minor failure. |