Sunday, April 28, 2013
5 disk backup tips to help avoid future missteps
* Data types. The data types you have directly impact the deduplication ratio and therefore the system you need. If your mix of data types is conducive to deduplication and has high deduplication ratios (e.g., 50:1), then the deduplicated data will occupy less storage space and you need a smaller system. If you have a mix of data that does not deduplicate well (i.e., 10:1 or less data reduction), then you will need a much larger system. What matters is what deduplication ratio is achieved in a real-world environment with a real mix of data types. Here is an example to highlight this: If you have 10TB of data and you keep four weeks of retention, then without deduplication you would store about 40TB of data. With deduplication, assuming a 2% weekly change rate, you would store about 5.6TB of data, so the deduplication ratio is about 7.1:1 (40TB ÷ 5.6TB = 7.1:1). However, if you have 10TB of data, and you keep 16 weeks of retention, then without deduplication you would store about 160TB of data (10TB x 16 weeks). With deduplication, assuming a 2% weekly change rate, you would store about 8TB of data, which is a deduplication ratio of 20:1 (160TB ÷ 8TB = 20:1).