1) Multi-user Omnis 3+
Omnis 3+ multi-user version is a true multi-user program and will allow several
users to access the same data simultaneously. The record-locking facility in
Omnis 3+ automatically prevents two or more users from attempting to modify the
same information at the same time, but allows an unlimited number of users to
read the same information. The same copy of multi-user Omnis 3+ may be used to
access different databases simultaneously. These features are built in and are
transparent to both the user and the developer.
In order to use the multi-user version of Omnis 3+, care must be taken in
installing Omnis 3+ and in configuring the network environment. Failure to
properly install Omnis 3+ or correctly configure the network may result in the
inability to run Omnis 3+ in the multi-user environment. In most cases, it
could also result in the corruption or loss of data.
2) The Network
Multi-user Omnis 3+ may be installed on Corvus disk drives residing on the
Corvus Omninet using the Contellation III (Release 2 or later) Network Software
for the Macintosh. If you have the wrong system software, do not attempt to
install Omnis 3+, call your dealer or Corvus to obtain the correct software.
We have assumed at this point that you have properly installed the network
software and have physically connected your network together.
3) Volumes
There are four types of volumes in the Corvus environment: Private, Public,
Controlled, and Uncontrolled. The following is a brief description of each,
additional information is available in your Corvus manuals and/or guides.
Private - can only be mounted by the owner; can be mounted as either
read/write or read-only
Public - can be mounted read-only by any user; can only be mounted read/write
by the owner
Controlled - can be mounted read/write by any one user; additional users may
only have read-only access
Uncontrolled - can be mounted read/write or read-only by any user at any time;
this is the type of volume used by Omnis 3+ shared files since all users must
be able to both read and write simultaneously
4) Recommended Volume Configuration
Each user must have his or her own private volume which contains the Macintosh
system documents (System, Finder, etc.) since these documents cannot be shared.
The Omnis3.info file should also reside in this volume inside your system
folder. Single-user applications can also be stored in this volume. The Omnis
3+ Utilities is a single-user application and should be stored in a private
volume.
An uncontrolled volume should contain the Omnis 3+ program. The size of this
volume is determined by the multi-user applications that are to be stored in
this volume. Print resource documents (LaserWriter and LaserWriter Prep) must
also be in this volume. The ImageWriter driver can also be stored in this
volume, but care has to be taken to make sure that only one user at a time
tries to print using this driver since it is a single-user resource. Loss of
data may occur if more than one person tries to print using this resource.
A second uncontrolled volume should be created to contain the Omnis 3+
libraries and data files. This volume should be made as large as the
anticipated size of all the data files. If possible, the volume should have
enough free space to hold a copy of the largest anticipated data file in case a
data reorganization is necessary.
5) Omnis 3+ Multi-user Considerations
Always maintain backup copies of all libraries and data files.
No other copy of Omnis 3+ should be available to the user of a multi-user
version of Omnis 3+. Loss of data may occur if a user tries to access a
database that is already being used by another copy of Omnis 3+.
Creation of new libraries or data files must be done through the Utilities in a
private volume.
Omnis 3+ multi-user cannot automatically extend the size of the library or the
data file. When the space allocated to the files have been used up, the user
will get messages that will inform them that the file is full. Use the Omnis
3+ Utilities to increase the size of the library or data file. At this point,
it is recommended that all other users be logged off.
Omnis 3+ multi-user stores internal semaphore flags in the library to keep
track of which records are being accessed. If Omnis 3+ or the network is
interrupted while executing a multi-user application, a semaphore lock-up or
corruption may occur. This will result in abnormal behavior while using the
Omnis 3+ multi-user application. If this happens, there are two ways to clear
the semaphore table:
Reboot Omnis 3+ while holding down the "Command-S" keys. Keep holding the keys
down until the application has successfully launched.
Mount the volume which contains the library in a private volume and launch the
Utilities program. Select the library with the corrupted semaphore table and
go into "Library Utilities". Delete the semaphore table. This is the format
labelled "WORK999". This will cause Omnis 3+ to re-create a new semaphore
table when the library is launched. Mount the volume as an uncontrolled volume
and launch the library.
Note: Apple Computer, Inc. is not responsible for the contents of this article.
Blyth Software