A simple analysis for the transient buffer hit probability for a system starting with an empty buffer is presented. The independent reference model (IRM) is used for buffer accesses. It is shown that the expected buffer hit probability when the buffer becomes full is virtually identical to the steady state buffer hit probability when the replacement policy is least recently used (LRU). The method is generalized to estimate the transient behavior of the LRU policy starting with a non-empty buffer. It is shown that this method can be used to estimate the effect of a load surge on the buffer hit probability. It is also shown that after a short load surge, it can take much longer than the surge duration for the buffer hit probability to return to its steady state value.>

Replication at the partition level is a promising approach for increasing availability in a Shared Nothing architecture. We propose an algorithm for maintaining replicas with little overhead during normal failure-free processing. Our mechanism updates the secondary replica in an asynchronous manner: entire dirty pages are sent to the secondary at some time before they are discarded from primary's buffer. A log server node (hardened against failures) maintains the log for each node. If a primary node fails, the secondary fetches the log from the log server, applied it to its replica, and brings itself to the primary's last transaction-consistent state. We study the performance of various policies for sending pages to secondary and the corresponding trade-offs between recovery time and overhead during failure-free processing.

Several existing distributed file systems provide reliability by server replication. An alternative approach is to use dual-ported disks accessible to a server and a backup. The two approaches are compared by examining an example of each. Deceit is a replicated file server that emphasizes flexibility. HA-NFS is an example of the second approach that emphasizes efficiency and simplicity. The two file servers run on the same hardware and implement SUN's NFS protocol. The comparison shows that replicated servers are more flexible and tolerant of a wider variety of faults. On the other hand, the dual-ported disks approach is more efficient and simpler to implement. When tolerating single failure, dual-ported disks also give somewhat better availability.>

Investigates the issues involved in using multiprocessors for transaction processing. The authors use a simulation model to study the behavior of two different architectures, namely shared everything and shared nothing. In shared everything, any processor can access any disk and all memory is shared. In shared nothing, neither disks nor memory is shared. They study the effects of data contention and resource contention in both of these architectures. They quantify the effects of intraquery parallelism on both architectures under different operating conditions.>