Dell DR4300e NetVault Backup - Best Practices for Setting up VTL Containers an - Page 18

NetVault Backup nVTL setup and configuration -- best practices Due to various factors such as data-set size, data-set iteration or count, retention period, and change rate, it can be difficult to determine the best VTL size and configuration for any deduplication situation. One of the best practices is to size the VTL to no more than 10x the physical available disk space or to assess how much data the customer has to back up and the required retention periods for each set of data. Ensure that neither of these guidelines is exceeded when you create the virtual media for the VTL, and set the drive count to equal the number of desired simultaneous jobs or data streams without exceeding the maximum guidelines set forth by the vendor. Example: Starting with a storage appliance with 2TB of physical disk space. Based on the 10x usage recommendation, you can create a VTL of 20TB of total storage. But given that the data backed up per week is 2TB and data retention is 4 weeks, the total amount of data stored at any given time would only be 8TB. Thus, reducing the VTL to 10TB would be a more efficient use of space. After the overall size of the VTL is determined, the number of virtual drives to create and the granularity of the VTL is the next consideration. Most storage-appliance operating environments can effectively handle a set number of streams. Any read or write operation to and from a VTL virtual drive would denote a stream. Usually, the number of virtual drives to create in the VTL should reflect what is required to support simultaneous streams, or concurrent jobs. Creating an excessive number of drives does not yield any benefits and could lead to performance degradation. It is also important not to exceed the number of streams supported by the appliance vendor's operating environment when creating VTLs and virtual drives. Media size is the final consideration. Unlike physical media, virtual media can be created to any size within the allowed range set by the appliance. So proper media size selection is important to ensure smooth operation of the VTL. Creating a small number of large media will extend the retention of expired data and prevent proper recycling within a media pool. Creating a large number of small media puts a strain on the NetVault Backup Media Manager process and can cause contention between resources. Dell recommends that the media size be made to accommodate for the media- group retention policy so that when the retention period is expired for that group, all items on the media expire as well, thus allowing for the reuse of the applicable virtual media. 18 Best practices for setting up Dell VTL Container or NetVault Backup native virtual tape library (nVTL)