5 Durability

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There appear to be two meanings of the word durability with respect to technical products: life-cycle durability and database durability.

Life-cycle durability

In the first sense, durability refers to the length of the working life of tool. We could call this "life-cycle durability." A durable tool lasts longer and thus requires less frequent replacement, thereby saving resources.

An introduction to life-cycle durability is found in the article "Buying Appliances" by Eric Morris. Morris notes that the "perception that buying low priced items can result in substantial savings" is often fallacious. On the contrary, "buying the more expensive appliances that save energy and are very durable can give the most value for a person’s money." In particular, "you avoid the added costs that you would incur if you had to have them repaired or replaced all the time."

The website of the EcoDesign Team of the Institute for Engineering Design at the Vienna Technical university provides a durability checklist to be used in the design of durable products.

Database durability

The term "durability" is used with a rather different meaning with respect to database systems. According to the Wikipedia article on "Durability (computer science)," database durability means that transactions that are committed will survive permanently and will not be undone by system failure. For example, if a flight booking database system reports that a seat has successfully been booked, then the seat will remain booked even if the system crashes: this is ensured by saving the transaction’s log records to disk before acknowledging commitment. Durability also guarantees that the system will not rollback the transaction because the seat was double-booked: it must check availability before acknowledging that the seat has been booked. The only way a transaction can be undone after it has been committed is by a compensatory transaction.

Durability in this sense does appear to be a convivial characteristic of databases. However, it should come under "reliability," which is one of the criteria of "usability", rather than under "durability" in the sense of products that last a long time.