[Tweet “#Data Availability vs. Durability – An Important Difference You Should Know #datacenter”]. Years of data center experience shows that drive failures are usually not isolated incidents: when one drive in a RAID group fails, the likelihood of other group member failing increases. This means the tests are crucial to understanding both the durability and reliability of the product. If you are a data center planner, architect or an IT professional looking to understand the importance of both I encourage you to read his perspective on availability vs. durability in archive solutions. Data on traditional spinning hard drive systems can degrade with time, have errors introduced during copying, or become corrupted in any number of ways. Landing zone and long term storage use Azure Storage, which provides availability and redundancy for transaction log, ensuring data durability for committed transactions. All elements in the chain—cables, power supplies, cooling, drives, software (and even the sys admins) —can possibly fail, without forewarning, and disrupt access to users’ data. It is most often expressed as a percentage, using the following calculation: Availability = 100 x (Available Time (hours) / Total Time (hours)) For equipment and/or systems that are expected to be able to be operated 24 hours per day, 7 days per week, Total Time is usually defined as being 24 hours/day, 7 days/week (in other words 8,760 hours per year). Examples of Unstructured Data — 4 Enterprise Use Cases. Data availability is mainly achieved through RAID or erasure coding (where the data is broken into fragments, sharded and distributed across a storage pool); you would notice the SLAs align with the SLAs possible through those technologies. In addition, this requires replacement of the failed drive ASAP, be it weekends, holidays or the middle of the night. If your data is on a computer, external drive, or NAS in a home or office, you obviously want to keep the computing equipment away from water sources and other environmental hazards. How’s that for data durability? © 2021 Western Digital Corporation or its affiliates. This blog includes news across the Western Digital® portfolio including: G-Technology, SanDisk, WD and Western Digital. Western Digital Technologies, Inc. is the seller of record and licensee in the Americas of SanDisk® products. Availability: refers to the ability of a system or component to be operational and accessible if required (system uptime). Designed to provide 99.999999999% durability and 99.99% availability of objects over a given year Designed to sustain the concurrent loss of data in two facilities Amazon S3 further protects your data … Availability refers to the probability that a system performs correctly at a specific time instance (not duration). There are a number of ways that data can lose its integrity. Every organization needs its data to be accessible when requested and without corruption or other loss. Examples of these approaches are erasure coding and Reed-Solomon coding. This is usually documented as a percent of time per year, e.g. When operating @Scale this becomes even more apparent. Object storage systems will commonly monitor for any changes in the data, and often will automatically repair or provide warnings when data has been changed. 2 min read. Availability refers to the percentage of time that the infrastructure, system, or solution remains operational under normal circumstances in order to serve its intended purpose. A more contemporary perspective sees this differently and with two key, separate, measurements: availability and durability. Reliability, availability and serviceability (RAS), also known as reliability, availability, and maintainability (RAM), is a computer hardware engineering term involving reliability engineering, high availability, and serviceability design. Data availability is primarily used to create service level agreements (SLA) and similar service contracts, which define and guarantee the service provided by third-party IT service providers. What formerly took minutes can now take hours, or even days. Tailored services in Reliability, Availability, Maintainability and Safety for technological systems in aerospace: aircraft, rotorcraft, UAVs and Tier 1 mechanical, electrical and avionics systems. For example, eleven nines of durability is expressed as 99.999999999%. Robin Harris, president and chief analyst of StorageMojo, recently published a white paper discussing data availability vs. durability in archive solutions. That care starts with locating a facility in as safe a geographical location as possible, having secure facilities with controlled access, and monitoring and maintaining the storage infrastructure (chassis, drives, cables, power, cooling, etc.). For example, a high speed train that is fast, energy efficient, safe, comfortable and easy to … Consider the potential competitive, financial or even legal impact of not being able to retrieve the archived master/reference copy of data. When shopping for a cloud storage provider, customers should ask a few key questions of potential storage providers. The chicken salad sandwich in the basket might be in great shape but you won’t be enjoying it. With Availability Zones, Azure offers industry best 99.99% VM uptime SLA. You want your data to be as intact and pristine on the day you retrieve it as it was on the day you stored it. This is known as redundancy. The bottom line is that no number of nines can absolutely protect your data. Availability is, in essence, the amount of time that an item of equipment or system is able to be operated when desired. Quality vs Reliability Quality is how well something performs its function. Object storage achieves data availability through advanced erasure coding whereby data is combined with parity information and then sharded and distributed across the storage pool. It’s not surprising that hyperscale data centers and cloud services providers use object-based storage to meet the needs for the highest data availability and data durability. Defining Reliability, Durability, Availability and Uptime. That will guide what strategy or vendor you should use to protect that data. 99.9% (or three nines) means that your data will be available to you from the data center and you will be unable to access the data for no more than about ten minutes per week, or 8.77 hours per year. 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