Data Domain: SNMP server fail to return queries to client
Summary: An SNMP daemon can be enabled on the Data Domain (DD) for monitoring purposes. This is also needed when integrating the Data Domain with various backup applications, such as Avamar. Failures for the DD to return timely responses to the SNMP collector or backup application may result in alerts being posted on those remote servers for the DD. ...
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Symptoms
Simple Network Management Protocol (SNMP) is based on the stateless UDP protocol.
It is a simple, fast way for an SNMP client to query an SNMP server for information and depending on configuration, to also set changes remotely.
This happens by identifying the item of data to be queried or set by a known Object ID (OID).
Note the Data Domain (DD) SNMP agent only supports read queries, but not setting of information.
On a regular host, the SNMP daemon replies to incoming requests.
The replies are typically fast. The queries tend to be for items the underlying operating system provides quickly: process and load information, network traffic details, so forth
The Data Domain gives this generic information and also Data Domain-specific data.
Some of these are collected through "sms" jobs from the SNMP agent when the query is received. Some of these queries may be for data that takes extra time to be collected.
The end result is that, depending on the configured timeout on the SNMP client, some queries to the DD may appear to have been lost or not replied to at all, when it was the DD taking a longer time to respond. The DD SNMP agent is single-threaded, so it will only service one SNMP query at a time. If a query takes a longer time to be processed, all queries received afterwards may be either dropped or replies made after the client-side timeout has expired, resulting in further errors.
It is a simple, fast way for an SNMP client to query an SNMP server for information and depending on configuration, to also set changes remotely.
This happens by identifying the item of data to be queried or set by a known Object ID (OID).
Note the Data Domain (DD) SNMP agent only supports read queries, but not setting of information.
On a regular host, the SNMP daemon replies to incoming requests.
The replies are typically fast. The queries tend to be for items the underlying operating system provides quickly: process and load information, network traffic details, so forth
The Data Domain gives this generic information and also Data Domain-specific data.
Some of these are collected through "sms" jobs from the SNMP agent when the query is received. Some of these queries may be for data that takes extra time to be collected.
The end result is that, depending on the configured timeout on the SNMP client, some queries to the DD may appear to have been lost or not replied to at all, when it was the DD taking a longer time to respond. The DD SNMP agent is single-threaded, so it will only service one SNMP query at a time. If a query takes a longer time to be processed, all queries received afterwards may be either dropped or replies made after the client-side timeout has expired, resulting in further errors.
Cause
Not applicable.
Resolution
The DD SNMP daemon is single-threaded and there are no plans to make it parallel so that several queries may be serviced simultaneously.
There is a functional need for some queries to trigger "sms" jobs for collecting the data, some of these jobs while running normally, may take more time to complete than the response timeout period of the SNMP client. Depending on the client, there may be some tuning available to extend this timeout to a longer value.
If your SNMP client or backup application sees repeated errors collecting SNMP data from a Data Domain, open a support request with your contracted support provider, gather all the possible details, a Support Upload Bundle, and see this KB article when providing the details.
There is a functional need for some queries to trigger "sms" jobs for collecting the data, some of these jobs while running normally, may take more time to complete than the response timeout period of the SNMP client. Depending on the client, there may be some tuning available to extend this timeout to a longer value.
If your SNMP client or backup application sees repeated errors collecting SNMP data from a Data Domain, open a support request with your contracted support provider, gather all the possible details, a Support Upload Bundle, and see this KB article when providing the details.
Affected Products
Data DomainProducts
Data DomainArticle Properties
Article Number: 000057185
Article Type: Solution
Last Modified: 27 Dec 2023
Version: 5
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