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Figure 1: The HP StoreOnce Backup System with usable capacity and backup speeds before the effects of deduplication
As an indication, vRanger daily full backups of virtual machines could have a deduplication ratio of up to 50:1,
whereas daily incremental backups could get around 10:1. This is indicative only, and the strong recommendation is
to run a proof of concept when evaluating deduplication ratios to size the protection solution.
For reliability and ease of management the StoreOnce Backup System are built on HP ProLiant machines and HP disk
systems. The unique HP StoreOnce software is optimized to this platform. It is important to ensure the firmware and
software in the StoreOnce Backup Systems is fully up-to-date. Check at: http://www.hp.com/support.
HP StoreOnce deduplication technology
HP StoreOnce is an inline data deduplication technology. It analyzes the backup data streams as they are written to
the appliance and segments the data streams into chunks. For efficient deduplication, the StoreOnce Backup System
segments the streams into variable sized chunks with an average size of around 4 KB. A hashing algorithm generates
an identifier (hash value) for each chunk that is stored in an index. When an incoming chunk generates a hash value
that already exists in the index, the duplicate chunk is not stored again. Instead a much smaller reference to the
duplicate chunk is stored. When a recovery is run, the required data is reassembled from the unique chunks and
referenced duplicate chunks.
Each HP StoreOnce Share has a Deduplication Store. This store is the deduplication domain. Deduplication does not
occur across Deduplication Stores. If a single Share is configured on the HP StoreOnce appliance, the deduplication
domain will be the entire appliance. The optimum number of Shares to configure depends upon how the backup
application will use the StoreOnce Backup System. It is recommended to configure a single Share for vRanger to use
for its Repository. If the data to be protected can be classified into like data types it may be beneficial to use separate
Shares/Repositories for each data type. Smaller Shares complete their Housekeeping tasks faster and are likely to
retain good performance over time.
The deduplication is one factor that will determine the capacity of the StoreOnce Backup System that is required. It is
recommended to use the
HP Sizing Tool
to help determine which appliance is required for a given environment.
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