Some notes for Tuning

If you experience system performance concerns, for example, you are exceeding your backup window, or if throughput appears to be slower than expected, consider the following:

Check the Streams columns of the system show performance command to make sure that the system is not exceeding the recommended write and read stream count. Look specifically under rd (active read streams) and wr (active write streams) to determine the stream count. Compare this to the recommended number of streams allowed for your system. If you are unsure about the recommended streams number, contact Data Domain Support for assistance.

Check that CPU utilization (1 process) is not unusually high. If you see CPU utilization at or above 80%, it is possible that the CPU is under-powered for the load it is required to currently process.

Check the State output of the system show performance command. Confirm that there is no cleaning (C) or disk reconstruction (D) in progress.

Check the output of the replication show performance all command. Confirm that there is no replication in progress. If there is no replication activity, the output reports zeros. Press Ctrl + c to stop the command. If replication is occurring during data ingestion and causing slower-than-expected performance, you might want to separate these two activities in your backup schedule.

If CPU utilization (1 process) is unusually high for any extended length, and you are unable to determine the cause, contact Data Domain Support for further assistance.

When you are identifying performance problems, it is important to note the actual time when poor performance was observed to know where to look n the system show performance output chronology.

An example of a network-related problem occurs when the client is trying to access the Data Domain system over a loo MBit network, rather than a 1 GB network:

Check network settings, and ensure the switch is running 1 GB to the Data Domain system and is not set to 100 MBit

If possible, consider implementing link aggregation.

Isolate the network between the backup server and the Data Domain system. Shared bandwidth adversely impacts optimum network throughput.

Consider implementing DD Boost to improve overall transfer rates between backup hosts and Data Domain systems.


About Ahmad Sabry ElGendi
This entry was posted in Data Domain, E20-385, EMC. Bookmark the permalink.

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