vRanger 7.8.5 - Integration Guide for NetVault SmartDisk

Garbage Collection process

When backups targeted to NetVault SmartDisk are retired, the data is removed from the backup database; however, the unique Chunks are not automatically removed from the Chunk Store. The NetVault SmartDisk Garbage Collection process is designed to remove orphaned Chunks from the Chunk Store and reclaim disk space. To do so, Garbage Collection maintains reference counts of added and deleted Chunks, and it deletes or rewrites partially used Chunk pages.

Garbage Collection cannot run at the same time as deduplication, because deduplication needs to write to the Chunk Store. During the configured Garbage Collection window, data waiting for deduplication is queued until Garbage Collection has completed. By default, the Garbage Collection window is from 18:00 through 06:00 on every night; however, you can revise this setting — for more information, see Configuring NetVault SmartDisk. Outside the Garbage Collection window, Garbage Collection is only started if no data is being deduplicated or is queued for deduplication. If data becomes available for deduplication outside the Garbage Collection window and Garbage Collection is active, Garbage Collection is stopped and deduplication proceeds.

Quest also recommends scheduling regular Garbage Collection to avoid delays associated with collecting large amounts of data.

NOTE: If a backup job that uses deduplication is canceled, the Chunk Store space used by segments that have already been deduplicated is not reclaimed until the next Garbage Collection occurs. Space used by the Staging Store and license enforcement is reclaimed immediately.

Planning your NetVault SmartDisk deployment

A NetVault SmartDisk deployment strategy includes multiple components, which you define before installing NetVault SmartDisk. To ensure a successful deployment, complete the following steps, which are described in detail in subsequent topics:

Defining which data to deduplicate

The first step in defining your NetVault SmartDisk Deployment Strategy is determining which data to deduplicate. Not all data benefits from deduplication; therefore, it is important to determine which data is targeted to use the NetVault SmartDisk Deduplication Option to reduce its storage footprint.

Additionally, the longer the data is retained in vRanger, the better the deduplication ratios. The deduplication ratios improve because more duplicate Chunks are found thus enabling the ability to pack more data into the same storage footprint. This ability enables even more protected data to be available through disk-based media. To obtain the most ideal deduplication ratios, Quest recommends a retention period of 12 weeks or more.

Identifying the ideal targets for deduplication

High deduplication ratios are achieved when multiple generations of the same data are targeted for the same NetVault SmartDisk Instance. Data that is an ideal target for deduplication includes the following:

NOTE: While email is an ideal target for deduplication, Single Instance Store (SIS), such as storage provided by Exchange, reduces deduplicated data; therefore, the deduplication ratio for the email server is not as high as other types of data.