oracle enterprise manager snmp and exadata

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How Enterprise Manager uses SNMP to monitor Exadata

Mike ChafinPrincipal Member of Technical StaffMaximum Availability Architecture


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What is SNMP?• SNMP (Simple Network Management Protocol) is an internet standard protocol for

sending and receiving information to and from devices

• SNMP standard is defined by Internet Engineering Task Force (IETF)

• Currently there are four versions: v1, v2, v2c and v3

• v2 was never widely adopted due to an overly complex security model

• v1 and v2c have several areas of incompatibility.

• V2c is the most widely prevalent implementation

• v3 primarily added security and remote configuration enhancements to SNMP

http://ietf.org/


SNMP Terminology• MIB (Management Information Base)

Collection of definitions which define the properties of the managed object

The MIB resides on the managed object

• Agent

Gathers information about the local device and saves them in the MIB

• SNMP Manager

A system that is configured to poll SNMP agents for information

Managed Object

MIB Database

SNMP Agent

SNMP Receiver

Monitoring Software

SNMP ReceiverNetwork


Why does Enterprise Manager use SNMP for Exadata?• Exadata Hardware components notify Enterprise Manager of component failures via

SNMP traps

• Information is also gathered using SNMP Get operations on certain components such as the PDUs

• SNMP is configured in various placesCELLCLIDBMCLIIBSWITCH ilomCisco Switch admin interfacePDU ilom website


SNMP Operations

• GetRequestA manager-to-agent request to retrieve information

• SetRequestA manager-to-agent request to change a value

• GetNextRequestA manager-to-agent request to discover available variables and their values

• GetBulkRequestA manager-to-agent request for multiple iterations of GetNextRequest

• ResponseReturns variable bindings and acknowledgement from agent to manager for GetRequest, SetRequest, GetNextRequest, GetBulkRequest and InformRequest

• TrapAsynchronous notification from agent to manager. SNMP traps enable an agent to notify the management station of significant events by way of an unsolicited SNMP message.

• InformRequestAcknowledged asynchronous notification


SNMP Flow

• There is no need to configure snmpd on the agent hosts to receive traps

• The EM agent contains code to act as a receiver

• All rack components should be configured to send SNMP traps to both the primary and backup monitoring agents

• Relevant information is then sent from the agent to the OMS for processing and the creation of Incidents


SNMP Community String

• Sent along with each GET request

• Allows access to the specified Managed Object

• Used only in v1, v2 and v2c

• Most objects ship with a default community string of public

• Enterprise Manager uses read-only community strings


Exadata Component SNMP Configuration

• During Exadata discovery some components are automatically configured for SNMP

InfiniBand Switches (v2c)

Storage Servers (v1)**(Plug-In version 12.1.0.2) and later. Earlier versions require manual entry

• Enter the desired community string on screens eight and nine of discovery

• Always use a secure community string!


Exadata Component SNMP Configuration(contd.)• Remaining components must be manually configured

Compute Node ilom (v2c)

Cisco Switch (v1)

PDUs (v1)


Exadata Compute Node SNMP Configuration• Compute nodes are configured using dbmcli (Exadata version 12.1.2.1.0 and later) or

exadata_mon_hw_asr.pl in earlier versions

dbmcli -e "ALTER DBSERVER snmpSubscriber=((host='[agent1_hostname]',port=[agent1_port],community=‘internal',type=asr),host='[agent2_hostname]',port=[agent2_port],community=‘internal',type=asr))“

• “type=asr” specifies that the SNMP version should be v2c

• To Verify the configuration on the Compute Nodedbmcli -e "LIST DBSERVER attributes snmpSubscriber“

• There should be an entry for the hosts and ports of both monitoring agents((host=agent1_hostname,port=agent1_port,community=Internal,type=asr),(host=agent2_hostname,port=agent2_port,community=Internal,type=asr))


Exadata Ethernet Switch SNMP Configuration

• Login to the switch and enter configuration mode ssh cisco-switch-host -l <admin user> User Access Verification Password: > enable Password: # configure terminal Enter configuration commands, one per line. End with CNTL/Z. #

• Allow access for the agents#access-list 1 permit agent1_ip_address agent2_ip_address

• Add agent subscriptions#snmp-server host [agent1_ip] version 1 internal udp-port [agent1_port]#snmp-server host [agent2_ip] version 1 internal udp-port [agent2_port]

• Set the switch to only send relevant traps#snmp-server enable traps envmon

• Save the configuration # end# copy running-config startup-config


Exadata Ethernet Switch SNMP Configuration

• Verify the configuration#show configuration

<TRIMMED>

snmp-server host agent1_ip public udp-port agent1_port entity envmon config snmpsnmp-server host agent2_ip public udp-port agent2_port entity envmon config snmp

<TRIMMED>


Exadata PDU SNMP Configuration

• Login to the PDU with a web browser

• Click on the “Net Configuration” button

• Scroll down to the SNMP section

Ensure “SNMP enable” option is checked

Add an entry with each agent’s IP and community string

Select the v1 radio button


Exadata PDU SNMP Configuration

• Next click the Submit button

• Repeat the above steps on the second PDU


Verify Storage Server SNMP Configuration• To Verify the configuration on the Storage Server

cellcli -e "LIST cell attributes snmpSubscriber“

• There should be an entry for the hosts and ports of both monitoring agents((host=agent1_hostname,port=agent1_port,community=Internal,type=asr),

(host=agent2_hostname,port=agent2_port,community=Internal,type=asr))

• If running an Exadata Plugin version below 12.1.0.2 the cell must be manually configured as shown below

cell -e "ALTER CELL snmpSubscriber=((host='agent1_hostname',port=agent1_port, community=‘internal',type=asr),(host='agent2_hostname’,port=agent2_port,community=‘internal',type=asr))“


Verify Infiniband SNMP Configuration

• Login to the Infiniband switch with a web browser

Select ConfigurationAlert Management

• There should be an entry for each agent with the followingLevel=minorDestination=agent_ip,agent_port,snmp1 v1,community “community string”


Finding SNMP Information in Enterprise Manager

• There is no way to view some target SNMP information such as community string in Enterprise Manager once the target is discovered

• However repvfy can be used to extract the informationrepvfy -tns haem.world -pwd notwelcome1 dump exadata_validation -name "DB Machine

scab02.us.oracle.com“

• For more information on repvfy see MOS Note 421053.1


Conclusion• With SNMP configuration complete any hardware faults that occur on Exadata rack

components should be reported to Enterprise Manager.

• These faults can be viewed in Enterprise Manager Incident Manager

• For more information on Incident Manager : https://docs.oracle.com/cd/E24628_01/doc.121/e24473/incident_mgmt.htm#EMADM9790


References

• For more information refer to: Enterprise Manager Exadata Management Getting Started Guide

• For more information on Exadata Monitoring refer to: Exadata health and resource usage monitoring

• For more information on repvfy see MOS Note 421053.1

https://docs.oracle.com/cd/E24628_01/doc.121/e27442/ch4_post_discovery.htm#EMXIG143



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oracle enterprise manager snmp and exadata

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