
Dawn renee Campbell, Senior Product Manager for NetVault: SmartDisk & NetVault: Backup
After you have determined how much NetVault: SmartDisk (NVSD) capacity you need to license, the next step is calculating how much physical disk space you will need.
As we discovered in my Calculating NetVault: SmartDisk License Capacity blog, NVSD is licensed based on the Logical Capacity of the data that it can store. However, in Deduplicated NVSD Instances, Logical Capacity does not match Physical Capacity or physical disk space. This is because NVSD Deduplication Option packs up to 12 times more protected data into the same storage area for a 92% reduction in storage footprint.
Deduplicated NVSD Instances
A Deduplicated NVSD Instance can have a combination of both Deduplicated and Non-Deduplicated data. In this configuration, calculating the total Physical Capacity or physical disk space is comprised by calculating the Physical Capacity for the Deduplicated Backups followed by calculating the Physical Capacity for the Non-Deduplicated Backups and totaling the sums.
Deduplicated Backups
The Physical Capacity or physical disk space required for Deduplicated Backups in Deduplicated NVSD Instances is equal to the Size of Weekly Full Backups + Unique Data Size and is calculated using the following formula:
(Size of Weekly Full Backups) +
Size of Weekly Full Backups + ((Size of Weekly Full Backups * Weekly Change Rate)
* Weekly Full Backup Retention Period)
+ (Size of Daily Backups * (Number of Daily Backups between Weekly Full Backups
* Daily Backup Retention Period))
Non-Deduplicated Backups
The Physical Capacity or physical disk space required for Non-Deduplicated Backups in a Deduplicated NVSD Instance is calculated using the following formula:
(Size of Non-Deduplicated Weekly Full Backups * Weekly Full Backup Retention Rate)
+ (Size of Non-Deduplicated Daily Backups * (Number of Daily Backups between Full Backups * Daily Backup Retention Period in Weeks))
Total Required Disk Space = Deduplicated Backup Disk Space + Non-Deduplicated Backup Disk Space
The Total Required Disk Space is divided into the Staging Store and the Chunk Store. If different file systems or disk spindles are going to be utilized for the Staging Store and the Chunk Store, it is important to know how much of the Total Required Disk Space will be allocated to the Staging Store versus the Chunk Store. The calculations below can be used to make this determination.



