Deduplication Considerations

Some data deduplication characteristics and considerations are as follows:

• You can specify a data deduplication device as the destination in a regular backup job.
• You can specify a data deduplication device as the staging device, the final destination device, or both. However, you cannot choose the same deduplication device for both staging and final destinations.
• You can specify different retention schedules for different jobs that all use the same deduplication device.
• You can Optimize data deduplication to improve throughput by deduplicating only the files that have changed since the last backup, except for stream-based files, such as SQL, SharePoint, Exchange, and Oracle data, which cannot be optimized. Optimization is enabled by default.
• You can create deduplication devices only on NTFS volumes.
• Deduplication groups are excluded from jobs that use * groups.
• You cannot use Encryption or Compression with deduplication devices.
• You can specify a purge policy for final destination when using a deduplication device. This is not possible using a normal FSD.
• You can specify a GFS rotation to a deduplication device where all full and incremental/differential backups are submitted to the same device, whereas GFS jobs to an FSD create daily, weekly, and monthly media.
• Due to the manner in which Oracle RMAN backup session header data is populated, the deduplication process cannot detect duplicate Oracle RMAN backup sessions and deduplicate the redundant sessions. However, the Global Deduplication process lets Arcserve Backup examine and handle Oracle RMAN backup sessions. For more information, see Global Deduplication.
• As a best practice, when backing up data on servers running Window Server 2012 related to agent backups, (for example, the Agent for Oracle and so on), enable NTFS Deduplication when you discover that the backup data compression ratios are lower than expected. When used with Arcserve deduplication, NTFS Deduplication can provide higher compression ratios of the backup data.
• However, when Arcserve backup compression ratios are relatively high (for example, greater than 70%), using NTFS Deduplication with Arcserve deduplication may not increase the overall backup compression ratios.