Mean Time to Meaningless: MTTDL, Markov Models, and Storage System Reliability
نویسندگان
چکیده
Mean Time To Data Loss (MTTDL) has been the standard reliability metric in storage systems for more than 20 years. MTTDL represents a simple formula that can be used to compare the reliability of small disk arrays and to perform comparative trending analyses. The MTTDL metric is often misused, with egregious examples relying on the MTTDL to generate reliability estimates that span centuries or millennia. Moving forward, the storage community needs to replace MTTDL with a metric that can be used to accurately compare the reliability of systems in a way that reflects the impact of data loss in the real world.
منابع مشابه
An Efficient Method for Reliability Evaluation of Data Storage Systems
The effectiveness of the redundancy schemes that have been developed to enhance the reliability of storage systems has predominantly been evaluated based on the mean time to data loss (MTTDL) metric. This metric has been widely used to compare schemes, to assess tradeoffs, and to estimate the effect of various parameters on system reliability. Analytical expressions for MTTDL are typically deri...
متن کاملMost Probable Paths to Data Loss: An Efficient Method for Reliability Evaluation of Data Storage Systems
The effectiveness of the redundancy schemes that have been developed to enhance the reliability of storage systems has predominantly been evaluated based on the mean time to data loss (MTTDL) metric. This metric has been widely used to compare schemes, to assess tradeoffs, and to estimate the effect of various parameters on system reliability. Analytical expressions for MTTDL are typically deri...
متن کاملReliability Models for Highly Fault-tolerant Storage Systems
We found that a reliability model commonly used to estimate Mean-Time-To-Data-Loss (MTTDL), while suitable for modeling RAID 0 and RAID 5, fails to accurately model systems having a fault-tolerance greater than 1. Therefore, to model the reliability of RAID 6, Triple-Replication, or k-of-n systems requires an alternate technique. In this paper, we explore some alternatives, and evaluate their e...
متن کاملWhen MTTDLs Are Not Good Enough: Providing Better Estimates of Disk Array Reliability
While mean time to data loss (MTTDL) provides an easy way to estimate the reliability of redundant disk arrays, it fails to take into account the relatively short lifetime of these arrays. We analyzed five different disk array organizations and compared the reliability estimates obtained using their mean times to data loss with the more exact values obtained by directly solving their correspond...
متن کاملReliability Hierarchies
Hierarchies of diverse storage levels have been analyzed extensively for their ability to achieve both good performance and low cost. This position paper argues that we should view hierarchies also as a way to achieve both good reliability and low overhead. After discussing the design of a reliability hierarchy, we suggest two metrics to use in evaluating the overall reliability of a reliabilit...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2010