VOSS 3.1

New in this release, together with the Continuation Transactions, Persistent (”Long”) Continuation Transactions, Web Rendezvous, MVRC & MVCC features already in the 3.1 beta, is buffered transaction logging.

With a background log archive daemon which activates at specified intervals (by default 1500 milliseconds) to archive the contents of the log buffer file, buffering increases the maximum commit rate to 40 transactions per second on desktop hardware, which file flushing previously limited to about four.  If the archive interval is set to zero (from the Control Panel or by program) the archive daemon terminates and each transaction is logged and flushed on commit, as in previous releases. With the transaction log on a separate drive or network server, rollforward of secure backups of the logged virtual spaces allows recovery from general power outage and from head crash or malicious damage at a single machine.

Rollforward recovery applies all log entries archived since the backup, followed by all (self-validating) well-formed log entries readable from the log buffer file. If log buffer flushing is enabled then recovery of all committed transactions is assured (though reducing the maximum commit rate to about 15 transactions per second on a typical IDE drive), but is otherwise dependent on the behaviour of the particular disk drive on power outage during a write append in the last sector of the buffer file, which is read and re-written in whole, even though the operating system called an appending write. (AFAIK it is not possible to control an IDE drive at a sufficiently low level to allow implementation of ping-pong appends).

VOSS 3.145.01is available for download here under the GPLv3 open source project licence, please mailto:mail@logicarts.com re supported commercial licensing.

John
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