Calculating the required number of NetVault SmartDisk Instances
Three factors determine the number of NetVault SmartDisk Instances with the NetVault SmartDisk Deduplication Option enabled. If any of these factors are true, you must deploy multiple NetVault SmartDisk Instances. To determine the total number of NetVault SmartDisk Instances required, perform the following calculations:
The maximum result for the three calculations determines the number of NetVault SmartDisk Instances that must be deployed. For example, if the Unique Data Size calculation and the Deduplication Rate indicates that only one NetVault SmartDisk Instance is required, but the Ingest Rate calculation indicates that two NetVault SmartDisk Instances are required, you must deploy two NetVault SmartDisk Instances.
The Unique Data Size is the amount of unique data that is stored inside the NetVault SmartDisk Instance. An additional NetVault SmartDisk Instance must be deployed for every 15 TB of unique data on a 64-bit OS and for every 1.8 TB through 2.5 TB of unique data on a 32-bit OS, depending on the OS. Use the following calculation to determine the number of NetVault SmartDisk Instances based on the Unique Data Size:
100 GB = Size of Weekly Full Backups
10% = Weekly Change Rate
12 = Weekly Full Backup Retention Period in Weeks
10 GB = Size of Daily Backups
4 = Daily Backup Retention Period in Weeks
6 = Number of Daily Backups between Full Backups
The NetVault SmartDisk Ingest Rate is the rate at which data can be streamed into NetVault SmartDisk. Because data streams into the NetVault SmartDisk Instance through a user-defined port, the network bandwidth limits the speed at which data can be streamed. To ensure that all backups targeted to a NetVault SmartDisk Instance can complete during the backup window, divide the required ingest rate by the Maximum Sustained Network Bandwidth to determine the number of required NetVault SmartDisk Instances. Use the following calculation to determine the number of NetVault SmartDisk Instances based on the NetVault SmartDisk Ingest Rate and Network Bandwidth:
100 GB = Size of Weekly Full Backups
8 = Number of Hours in Backup Window
100 = Maximum Sustained Network Bandwidth (MB/Sec)
Rounded Up to Next Whole Number = 1 NetVault SmartDisk Instance
The NetVault SmartDisk Deduplication Rate is the rate at which NetVault SmartDisk deduplicates data. If NetVault SmartDisk deduplication is configured to run during the backup, the NetVault SmartDisk Deduplication Rate must be greater than or equal to the Ingest Rate to ensure that the deduplication process completes before the next weekly backup window begins.
Use the following to estimate the Deduplication Rates:
Use the following calculation to determine the number of NetVault SmartDisk Instances based on the Deduplication Rate and Ingest Rate:
100 GB = Size of Weekly Full Backups
10% = Weekly Full Backup Growth Rate
10 GB = Size of Daily Backups
6 = Number of Daily Backups between Full Backups
24 = Number of Hours in Daily Deduplication Window
50 = Deduplication Rate (MB/Sec)
Rounded Up to Next Whole Number = 1 NetVault SmartDisk Instance
The maximum result for the following three calculations determines the number of NetVault SmartDisk Instances that must be deployed:
The maximum result is one NetVault SmartDisk Instance; therefore, only one NetVault SmartDisk Instance is required in this example.
Determining the number of nondeduplicated NetVault SmartDisk Instances
A single factor determines the number of Nondeduplicated NetVault SmartDisk Instances:
The NetVault SmartDisk Ingest Rate is the rate at which data can be streamed into NetVault SmartDisk. Because data streams into the NetVault SmartDisk Instance through a user-defined port, the network bandwidth limits the speed at which data can be streamed. To ensure that all backups targeted to a NetVault SmartDisk Instance can complete during the backup window, divide the required ingest rate by the Maximum Sustained Network Bandwidth to determine the number of required NetVault SmartDisk Instances. Use the following calculation to determine the number of NetVault SmartDisk Instances based on the NetVault SmartDisk Ingest Rate and Network Bandwidth:
100 GB = Size of Weekly Full Backups
8 = Number of Hours in Backup Window
100 = Maximum Sustained Network Bandwidth (MB/Sec)
Rounded Up to Next Whole Number = 1 NetVault SmartDisk Instance
Calculating the total required physical disk space for licensed capacity
NetVault SmartDisk is licensed based on the front-end terabytes (TBs) or amount of data to be protected from all source machines. However, in Deduplicated NetVault SmartDisk Instances, Licensed Capacity does not match Physical Capacity or physical disk space. This mismatch is because the NetVault SmartDisk Deduplication Option packs up to 12 times more protected data into the same storage area for a 92 percent reduction in the storage footprint.
A Deduplicated NetVault SmartDisk Instance can have a combination of both Deduplicated and Nondeduplicated data. In this configuration, calculating the total Physical Capacity or physical disk space is achieved by calculating the Physical Capacity for the Deduplicated Backups, calculating the Physical Capacity for the Nondeduplicated Backups, and adding the sums.
The Physical Capacity or physical disk space required for Deduplicated Backups in Deduplicated NetVault SmartDisk Instances is equal to the Size of Weekly Full Backups plus the Unique Data Size. Use the following formula to calculate it:
100 GB = Size of Deduplicated Weekly Full Backups across all servers
10% = Weekly Change Rate
12 = Weekly Full Backup Retention Period in Weeks
10 GB = Size of Deduplicated Weekly Daily Backups
6 = Number of Daily Backups between Full Backups
4 = Daily Backup Retention Period in Weeks
Use the following formula to calculate the Physical Capacity or physical disk space required for Nondeduplicated Backups in a Deduplicated NetVault SmartDisk Instance:
10 GB = Size of Nondeduplicated Weekly Full Backups
12 = Weekly Full Backup Retention Period in Weeks
1 GB = Size of Nondeduplicated Daily Backups
4 = Daily Backup Retention Period in Weeks
6 = Number of Daily Backups between Full Backups
Total Required Disk Space = Deduplicated Backup Disk Space + Nondeduplicated Backup Disk Space
560 GB + 144 GB = 704 GB
The Total Required Disk Space is divided into the Staging Store and the Chunk Store. If you intend to use different file systems or disks for the Staging Store and the Chunk Store, it is important to know how much of the Total Required Disk Space is allocated to the Staging Store versus the Chunk Store. Use the following calculations to determine this amount.
The amount of time a Deduplicated Backup remains in the Staging Store is different than the amount of time a Nondeduplicated Backup remains in the Staging Store. Therefore, to determine the total disk space required for the Staging Store, you must calculate the size required for both Deduplicated Backups and Nondeduplicated Backups.
Total Staging Store Disk Space = Deduplicated Backup Disk Space + Nondeduplicated Backup Disk Space
During the NetVault SmartDisk Deduplicated Backup process, backups are initially streamed to the Staging Store where they remain until the deduplication process is finished. The Staging Store must be large enough to hold all the Deduplicated Backups while they await deduplication.
If the deduplication window overlaps the backup window, deduplication and backups occur at the same time. Each backup starts deduplicating after the backup job is finished. Also, large backups are broken into 400 GB segments. Each segment starts to deduplicate after it is received, even if the backup stream is still being streamed to the Staging Store. Therefore, the Staging Store only requires space to hold some portion of the total backup size. If the Staging Store runs out of space, backups pause until space becomes available, such as when a deduplication operation finishes.
The maximum disk space required for the Staging Store is equal to the Size of the Weekly Full Backups.
Backups that are not deduplicated are streamed into the Staging Store, where they remain until they are retired. Therefore, calculating the size of the Staging Store for Nondeduplicated Backups is identical to calculating the required physical disk space for Nondeduplicated Backups in a Deduplicated NetVault SmartDisk Instance.
10 GB = Size of Nondeduplicated Weekly Full Backups
12 = Weekly Full Backup Retention Period in Weeks
1 GB = Size of Nondeduplicated Daily Backups
6 = Number of Daily Backups between Full Backups
4 = Daily Backup Retention Period in Weeks
The amount of physical disk space required for the Chunk Store is equal to the Unique Data Size. To calculate the Unique Data Size or the size of the Chunk Store, use the following formula:
100 GB = Size of Weekly Full Backups
12 = Weekly Full Backup Retention Period in Weeks
10 GB = Size of Daily Backups
4 = Daily Backup Retention Period in Weeks
6 = Number of Daily Backups between Full Backups
Determining the capacity for nondeduplicated NetVault SmartDisk Instances
Because deduplication is disabled, the Physical Capacity or physical disk space required for Nondeduplicated NetVault SmartDisk Instances is equal to the amount of data stored in NetVault SmartDisk. The Nondeduplicated NetVault SmartDisk Instance consumes the same amount of disk space for the Staging Store that is required to hold all backup data written to the NetVault SmartDisk Instance over the entire retention span for that data. For example, if you back up 1 TB of data every week and retain all that data for two weeks, you need 2 TB of physical storage capacity for your Staging Store. If you back up that same 1 TB of data and move it to tape before the next backup is run, you need 1 TB of physical storage capacity in your Staging Store.
