Ten years ago, hardware failures were a big issue in data loss. Not any longer as technologies like mirroring and RAID have addressed this problem. The main culprits of data loss today are human error and/or unanticipated application interactions that lead to data corruption. The Wikibon community estimates that data loss from human error and software glitches can exceed 50% of incidents of data loss. This is the domain of continuous data protection (CDP).
CDP, whether file or block-based, should be targeted at those 'life or death' applications that are deemed mission critical. These are often applications that are:
- 7X24
- High write:read ratios
- Mission critical database
- Applications with stringent recovery requirements
- Applications enduring lots of change (e.g. early-in-life)
CDP however can be expensive, often requiring 2.5 - 5X the amount of storage for applications being continuously backed up, CDP software licenses (often upwards of $50K), increased network bandwidth and server overheads, integration/implementation costs (often in excess of $75K), testing and ongoing maintenance costs of $30K - $40K annually.
Action Item: CDP is not for everything but rather should be focused on those applications with recovery requirements that are the most demanding. Users should conduct a proper RTO and RPO assessment as a starting point and carefully assess the cost implications of CDP to ensure it's targeted at the right applications.
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