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# Data Deduplication Ratio Calculator

## Data Deduplication Ratio

The data deduplication ratio is a measure of how effectively data deduplication reduces the amount of stored data. It represents the ratio of the original amount of data before deduplication to the amount of data after deduplication.

Understanding how to estimate your data deduplication ratio can be complex, as it depends on several variables that influence how much data can be reduced. Here, we break down these factors and introduce a formula that can help you predict the deduplication ratio you might achieve in your environment.

## Key Factors Influencing Data Deduplication

• Redundant Data: The presence of redundant data on your servers plays a significant role in achieving higher deduplication ratios. For example, if your servers run similar files or databases across multiple Windows systems, expect a substantial boost in the deduplication ratio. On the contrary, environments with diverse operating systems and file types typically see lower ratios.

• Rate of Data Change: The frequency at which data changes impacts the deduplication ratio. A common benchmark, such as a 20:1 deduplication ratio, assumes an average data change rate of about 5%. If your data changes more frequently, you can anticipate a lower deduplication ratio.

• Precompressed Data: Many data deduplication algorithms also rely on compression to further reduce data. Vendors often advertise high deduplication ratios, assuming that compression can double the reduction. However, if your data includes large volumes of precompressed formats like JPEGs, MP3s, or ZIP files, the additional benefit of compression may be limited.

• Data Retention Period: The length of time you retain data affects the deduplication ratio. A longer retention period typically allows for a higher deduplication ratio. For example, achieving a deduplication ratio of 10:1 to 30:1 might require retaining a dataset over several weeks.

• Frequency of Full Backups: Regular full backups provide deduplication software with a complete view of your data, leading to higher deduplication ratios. The more often full backups are performed, the greater the potential for data deduplication, as the software can better identify and eliminate duplicate data.

## Deriving the Data Deduplication Ratio Formula

The formula to estimate the Deduplication Ratio ($\text{DR}$) is:

$\text{DR} = \frac{R \times T \times F}{C \times P}$

Variable Definitions:

• $\text{DR}$ - Deduplication Ratio
• $R$ - Redundancy Factor (how much redundant data you have)
• $T$ - Data Retention Period (how long you keep the data)
• $F$ - Frequency of Full Backups
• $C$ - Rate of Data Change (how often your data is updated)
• $P$ - Precompression Factor (how much of your data is already compressed)

Find the Deduplication Ratio ($\text{DR}$) given the following:

• $R = 10$
• $T = 20$ weeks
• $F = 5$
• $C = 2$
• $P = 3$

$\text{DR} = \frac{10 \times 20 \times 5}{2 \times 3} = \frac{1000}{6} \approx 166.67$
Therefore, the Deduplication Ratio is approximately $166.67$.