HP StoreOnce Backup System Concepts and Configuration Guidelines (BB877-90913, November 2013)

Figure 2 Recommended configuration using multiple streams
Effect of multiple streams on StoreOnce Performance
The following graph, illustrates the relationship between the number of active data streams and
performance; the appliance is assumed to be one of the larger models where more than 24 streams
(if fast enough) can achieve best throughput. The throughput values shown are for example only.
Along the x axis is the number of concurrent streams. A stream is a data path to a device configured
on StoreOnce; on VTL it is the number of virtual tape drives, on NAS the number of writers, on
Catalyst stores the number of streams.
Along the Y axis is the overall throughput in MB/sec that the StoreOnce device can process – this
ultimately dictates the backup window. As a backup window begins, the number of streams
gradually increases and we aim to have as many streams running as possible to get the best
possible throughput to the StoreOnce device. As the backup jobs come to an end, the stream count
starts to decrease and so the overall throughput to the StoreOnce device starts to reduce.
The StoreOnce device itself also has a limit which we call the maximum ingest rate. In this example
it is 1000MB/sec. The > 24 streams value is calculated using “Infinite performance hosts” to
characterize the HP StoreOnce ingest performance.
As long as we can supply around 24 data streams at the required performance levels we keep
the StoreOnce device in its “saturation zone” of maximum ingest performance.
18 HP StoreOnce technology