Data Domain: SNMP Server Fails to Return Queries to Client

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. Depending on configuration, it can also set changes remotely.
This is done by identifying the item of data to be queried or set by a known Object ID (OID).

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, such as process and load information, and network traffic details.
The Data Domain provides 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. In reality, the DD is 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 replied to after the client-side timeout has expired. This results in further errors.

Not applicable.

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 and a Support Upload Bundle. Reference this KB article when providing the details.