About the MSDP fingerprint cache
NetBackup uses fingerprints to identify the data segments in the backup data. NetBackup writes only unique data segments to a . If a segment is already in storage meeting the preconfigured data locality requirements, NetBackup does not store it again.
See About MSDP fingerprinting.
The storage server maintains an index cache of the fingerprints in RAM. After startup, the NetBackup Deduplication Engine (spoold) loads fingerprints into this cache in the background. The background loading continues until all required fingerprints are loaded or the configured cache capacity is reached. The fingerprints in the cache are then updated as jobs run.
For each backup job, the MSDP OST (OpenStorage) plug-in requests the fingerprints of the last backup of the current client from the MSDP server. The fingerprints are stored in a size-limited cache in the memory of the MSDP OST plug-in. It's called the client-side fingerprint cache. The plug-in checks this cache for a fingerprint first. After a missed lookup, it requests the fingerprint lookup with the MSDP server.
You can configure the cache loading behavior.
See Configuring the MSDP fingerprint cache behavior.
You can also control the fingerprint cache seeding for clients.