Performance degradation accessing remote Vision files

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Problem:

Lack of performance accessing Vision files located in a shared directory

Resolution:

This issue may be caused by the opportunistic locking system of Windows.

Here are some useful information about it:

Opportunistic Locks
http://msdn.microsoft.com/en-us/library/windows/desktop/aa365433(v=vs.85).aspx

PC Ext: Explanation of Opportunistic Locking on Windows NT
http://support.microsoft.com/kb/129202

In most of the cases, opportunistic locking can lead to further error 98 (corruption of indexed file).
This is why Micro Focus usually suggest to limit the use of mapped shared drives to avoid this kind of errors.
The best approaches in client-server environments is to use AcuConnect Thin Client or AcuServer.

In some cases, the issue may be accentuated by a mixed network where new Windows 7 or 8 are now coexisting with older Operating Systems (i.e. Windows XP).
The opportunistic locking mechanism (SMB) was changed after Windows XP, introducing a new mechanism (SMB2) in Windows Vista and following Windows 7 and Windows Server 2008.

Here are some interesting articles about this argument:

What's new in SMB in Windows Vista
http://blogs.msdn.com/b/chkdsk/archive/2006/03/10/548787.aspx

Server Message Block
http://en.wikipedia.org/wiki/Server_Message_Block

What version of SMB2 am I using on my Windows file server?
http://blogs.technet.com/b/josebda/archive/2010/10/26/what-version-of-smb2-am-i-using-on-my-windows-file-server.aspx

This caused further issues in network with mixed Operating System and mixed SMB.
i.e.:
- lack of performance, due to the time taken to "negotiate" which dialect to use;
- corruption of ISAM files, marked by file status 98.

As a good-programming advice, Micro Focus does not recommend the use of shared directories, strongly suggesting to use ACUCOBOL-GT native client-server software.

It is also very important to use the latest version of the runtime and Vision version 5.
This is the latest version of ACUCOBOL-GT File System.
Its characteristics and benefits may be found in the Documentation Set:

Indexed Files - Vision
http://documentation.microfocus.com/help/topic/com.microfocus.eclipse.infocenter.extendACUSuite/BKUSUSPROGS004.html

Opportunistic locking mechanism can be turned off or disabled following the instructions in the following article:

Opportunistic Locking
http://community.microfocus.com/microfocus/cobol/extend_and_acucobol/w/knowledge_base/17516.opportunistic-locking.aspx
(it is very important to evaluate this choice with the IT engineers before applying it in a real environment)

If the lack of performance remains, the best approach will be to test AcuConnect Thin Client or AcuServer.

Please, contact your local SupportLine engineer for further information about these softwares.

Support Incident numbers: 2781535, 2798787

Claudio Contardi
Product Support Engineer, Senior
Micro Focus

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