>Does it fail all at once with no warning, no way to perform post-mortem diagnostics, and no way to recover the data? Or does it fail with a gradual degradation

>Does it fail all at once with no warning, no way to perform post-mortem diagnostics, and no way to recover the data? Or does it fail with a gradual degradation of performance and capacity over time, and in a way that, if/when total failure occurs, the cause can be ascertained and the data still recovered somehow? how does that have any relation to an SLA? An SLA is a promise of a certain amount of uptime, with financial penalty for the provider if not met. A warranty is a promise of a certain product lifespan, with a financial penalty for the provider if not met. SLAs have nothing to do with providing diagnostic information.