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NOTE:
required to perform deduplication, select the larger number of nodes.
NOTE:
On the VLS6200, do not enable software compression and deduplication together.
Enabling software compression will drastically reduce the performance if deduplication is enabled.
Capacity Sizing
Several factors affect how much disk space is required for the desired retention scheme:
Data compression rate.
Daily change rate.
Retention policy, or the number of full and incremental backups retained.
"Scratch" space required for post-processing.
Download the HP Sizer tool to help determine your capacity needs. The tool is available on the
HP website: http://www.hp.com/go/storageworks/sizer.
Optimum Record Sizing
You must configure your backup application to use a record size (tape block size) of 256 KB when
using deduplication.
Optimizing File Server Deduplication
There are many reasons why you may get a low deduplication compression ratio.
For example, deduplication does not occur on:
Files less than 32 KB in size for File-level deduplication.
Files less than 8 KB in size for Backup-level deduplication.
File names that keep changing (such as some database dumps).
Backup sets less than 1 MB in size.
Database file backups with varying names (such as database dump files created with a Back
Up Database Task within an SQL Maintenance Plan).
If your file server contains the above items, it will not deduplicate efficiently.
In these cases, switch from File-level to Backup-level deduplication for more optimal results.
NOTE:
Deduplication statistics and reports only include the data that is eligible for deduplication.
For example, deduplication does not occur on unsupported formats. Therefore, that data is not
included in the reports.
NOTE:
If the file backup is very large or contains more than 2 million files, the VLS will
automatically switch itself to use Backup-level differencing because this will achieve more efficient
deduplication in these cases.
Media Management
To make the most of storage savings with Accelerated deduplication, consider the following:
Reclamation does not occur until a tape is full (and everything on the tape is either
delta-differenced, disabled, or unsupported).
The deduplication software cannot deduplicate versions of a backup that are on the same
cartridge; the versions are not deduplicated until a new version is written to a different virtual
cartridge.
If the number of nodes required for backing up data differs from the number of nodes
Design Considerations
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