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■ The client nbostpxy process moves the data to the PureDisk plug-in.
■ The PureDisk plug-in retrieves a list of fingerprints from the last full backup
for the client from the NetBackup Deduplication Engine. The list is used as a
cacheso the plug-indoes nothave to requesteach fingerprintfrom the engine.
■ The PureDisk plug-in performs file fingerprinting calculations.
■ ThePureDisk plug-insends onlyunique datasegments tothe PureDiskstorage
pool.
About deduplication fingerprinting
TheNetBackup Deduplication Engineuses a uniqueidentifier to identifyeach file
and each file segment that is backed up. The engine identifies files inside the
backup images and then processes the files.
The process is known as fingerprinting.
For the first deduplicated backup, the following is the process:
■ The PureDisk plug-in reads the backup image and separates the image into
files.
■ The plug-in separates files into segments.
■ For each segment, the plug-in calculates the hash key (or fingerprint) that
identifieseach datasegment.To createa hash,everybyte ofdata inthe segment
is read and added to the hash.
■ The plug-in compares it calculated fingerprints to the fingerprints that the
NetBackup Deduplication Engine stores on the media server. Two segments
that have the same fingerprint are duplicates of each other.
■ The plug-in sends unique segments to the deduplication engine to be stored.
A unique segment is one for which a matching fingerprint does not exist in
the engine already.
The first backup may have a 0% deduplication rate; however, a 0%
deduplication rateis unlikely.Zero percent meansthat allfile segments in the
backup data are unique.
■ The NetBackup Deduplication Engine saves the fingerprint information for
that backup.
For subsequent backups, the following is the process:
■ The PureDisk plug-in retrieves a list of fingerprints from the last full backup
for the client from the NetBackup Deduplication Engine. The list is used as a
cacheso the plug-indoes nothave to requesteach fingerprintfrom the engine.
117Deduplication architecture
About deduplication fingerprinting