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

[BillPedersen]

On Monday, October 15, 2012 11:02:18 AM UTC-4, BillPedersen wrote:
> 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
> 
> ----------
> 
> 
> 
> * 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/

SSIO V1 UPDATE AVAILABLE.

I have been informed my HP OpenVMS Engineering that there are update images available for those interested in testing this new feature on OpenVMS. Anyone interested in testing Serial Stream IO should contact OpenVMS.Programs at hp.com and request a kit. SSIO is an important precursor to the proper implementation of a fully compatible fork on OpenVMS for Unix Portability and Open Source Porting.

Information from HP OpenVMS Engineering:

SSIO IMAGE DETAILS –

1) SSIO Update

The latest set of SSIO images provides the following –

A) Fix to various major defects found internally

B) Fix to known problems mentioned in the previous version of SSIO V1 beta kits

C) Provides functionality to block concurrent SSIO access to the same file in cluster environment

Concurrent SSIO access to the file cluster-wide is handled as follows -

All the nodes would be able to open/close a given file but only one of the node would be able to successfully perform SSIO operations on the file. The node that requests the first SSIO operation will be able to successfully perform the SSIO operation. And until this node closes the file, all other nodes attempt to perform SSIO operation on the same file will be failed. i.e. the CRTL APIs supporting the SSIO functionality will fail with return status of -1.

Thanks for your continued interest and support.

Regards,

Bill Pedersen
CCSS - Computer Consulting System Services, LLC