The Case For Safe RAM

Battery-backed-up DRAM memories can be configured today to be almost as reliable as disk. This paper argues that it is cost-effective to employ Safe RAM in computer systems which support reliable updates. Safe RAM allows systems that support reliable updates, such as database and transaction processing systems, to perform more efficiently. We show how a response time improvement can always be realized, and how a throughput improvement can be realized to the extent that a system has had to limit disk utilization to achieve adequate response time. We also show that Safe RAM is cost-effective today for most applications and will become increasingly cost-effective as more caching is used, and as DRAM standby power and disk active power decrease.