[Info-vax] Shared Stream IO (SSIO) beta kit available for OpenVMS

[BillPedersen]

Shared Stream IO (SSIO) beta kit available for OpenVMS - contact OpenSource.OpenVMS at hp.com or OpenVMS.programs at hp.com to participate.

SSIO
====
Shared Stream IO feature provides POSIX compliant read/write to byte stream files.
Hence SSIO feature, the data consistency is guaranteed when mutiple processes are performing a Read/Write to non overlapping byte boundaries with the same block boundary.

Problems Addressed
------------------
- Lost Update Problem
When mutiple WRITERS are concurrently accessing non overlapping byte boundaries within the
same block boundary, one of the WRITERS' update is lost.

- Mix Update Problem
When a WRITER and READER are accessing the data concurrently, READER gets some data
which is before the WRITE is completed and some data which is after the WRITE is completed.

V1 Release
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* SSIO Feature release
Mutiple processes will be able to Read/Write data from non overlapping byte boundaries with the
same block boundary successfully.
- No Lost Update Problem
- No Mix Update Problem

* Stand Alone implementation
In this release, SSIO feature is supported only on a stand alone system.

* Write though cache
OpenVMS caching is write through cache.
When a applicaiton issues a IO, data is written to cache and then to disk and only then the IO
operation is considered complete.
SSIO write operation will continue to be a write through operation.


V2 Release
----------
* Next release of SSIO.

* Plans to enable Cluster support.

Bill Pedersen
https://sourceforge.net/p/vms-ports/wiki/Home/