All ReliaSoft applications from Version 8 on, as well as earlier versions of XFMEA/RCM++, work with standard databases that use the Microsoft Access file format in the back end for storing analysis data. This makes it possible to install and use the software without the need to purchase additional licenses for an enterprise database system (such as SQL Server or Oracle) and without requiring special IT infrastructure and support. However, standard database files (e.g., *.rsr22, *.rsr21) and standard library files (e.g., *.lb22, *.lb21) will be subject to the same limitations and vulnerabilities as any other Access database. For example, the maximum file size is ~ 2GB, maximum number of concurrent users is 255, etc. In addition, some specific database vulnerabilities are discussed in a Microsoft publication at http://support.microsoft.com/kb/283849/EN-US/. As this publication states:
"Microsoft Jet, the database engine that is used in Microsoft Access, is a file sharing database system. When Microsoft Jet is used in a multi-user environment, multiple client processes are using file read, write, and locking operations on a shared database. Because multiple client processes are reading and writing to the same database and because Jet does not use a transaction log (as do the more advanced database systems, such as SQL Server), it is not possible to reliably prevent any and all database corruption." [emphasis added]
Although ReliaSoft's developers have made every effort to reduce or eliminate the possibility that the software will induce a database error, there is no way to absolutely prevent corruption that might be caused by other factors, such as a faulty network hardware, an unexpected "crash" on your PC or a network interruption. Therefore, this document provides some general recommendations for standard precautions that all users can take to protect the data in their standard databases from this type of corruption and reduce the impact of the data loss if corruption is unavoidable.
For specific instructions on how to follow these precautions in a particular software version, you can search for "prevent corruption" in the help file.
1. Create backups regularly
As with any file that contains a large amount of valuable information that would be difficult to re-create, it is essential to make sure that you are diligent about creating and storing backup files.
2. Compact and Repair the database regularly
Using the "Compact and Repair" feature will help to reduce the size of the database file and help to protect against problems with the operation of the database.
3. Do not store the database in a shared network location if you suspect that your network connection and/or hardware may be unreliable
According to Microsoft, faulty network hardware is one of the main reasons why a file that uses the Microsoft Access database file format may become corrupted. As the Microsoft publication at http://support.microsoft.com/kb/283849/EN-US/ states:
"The cause can be one or more links in the hardware chain between the computer that the database resides on and the computer that has the database open. This list includes, but is not limited to, network interface cards, network cabling, routers, and hubs.
Hardware-based corruption is typically indicated by .mdb files that cannot be restored through the use of compacting, repairing, or Jetcomp. Hardware corruption will typically recur until the responsible hardware is repaired or replaced." [emphasis added]
[Note that in ReliaSoft software, the extensions are things such as *.rsr22 or *.lb22 rather than *.mdb.]
If you have experienced this type of corruption for a standard database file, it is recommended that you take steps to correct the network problem or refrain from accessing database files over the network. In such cases, you may choose to use an enterprise database instead (i.e., Oracle or SQL Server), which would be less vulnerable to network interruptions. Alternatively, you could keep the analysis altogether in a single shared standard database file but ask users to import the analysis to a separate "working" database on their own computers when there is a need to make substantial modifications. Users can then export the data back to the shared repository after the modifications are completed.
4. Do not allow the file size of the database to grow too large
Performance will be affected by the size of the database and the number of simultaneous users. Therefore, it is important for users to monitor the size of their database files and if they become too large, take steps to export the data into several smaller and more manageable files. Please be aware of the following factors, which can lead to very large database files:
If you try to open a standard database via the software and receive a message that says "Unable to open the database," this is an indication that the database file may have become corrupted. Please contact Support and provide as much information as possible about exactly what you were doing when the corruption occurred. Whenever possible, please provide a copy of the corrupted file. In some cases, ReliaSoft may be able to provide assistance with salvaging some or all of the affected data. However, in many cases, the best recourse may be to restore the latest backup from before the corruption occurred.
Information is provided "as is" without warranty of any kind.