Summary
I have an application on my workstation, server, or network share that produces data that I have been backing up. The backup is successful, however when I restore the data my application complains that the data file is corrupt, inconsistent, or not the right type. Why are the restored on-line data files unusable? This seems to happen often with Access databases, but other applications are also affected.
Resolution
For any critical production application, it is important to find out what special requirements are needed to back up and recover data files. It is equally critical in any backup strategy to identify, backup, and test the recovery of critical applications on a regular basis.
A "hot backup" is any backup taken while an application is on-line and active. DPX specifically supports hot backup for some enterprise level applications such as Microsoft SQL server, Exchange, Sybase, etc. For a full list of supported applications in DPX, please refer to the product Compatibility Guide. Unless your application is specifically supported by DPX for on-line backup, you will need to find out from your software vendor if on-line backup is supported and/or what your vendor's recommended data backup procedures are.
A "cold backup" is a backup of any application data where the application has been closed down properly and its data backed up when the application is off-line. Catalogic Software recommends a cold backup for any application data that is not specifically supported by DPX, or where the viability of hot backup data from the application is unknown. Shutting down your application properly and backing up your data is the safest way to assure that the data can be successfully restored at a later date. DPX does not specifically have support for smaller database driven applications such as Microsoft Access, Peachtree, Quicken, MS Money, etc.
Many database applications open their data files and leave the on-disk versions in an "open", "temporary", or "inconsistent" state until either the application synchronizes unwritten (cached) data, closes and saves the data file in use, or performs specific internal backup procedures. Similar situations can occur with applications that open and share data across a network; network attached nodes will often cache data and not necessarily update the on-disk version until a later time.
If you have backed up data from an application that was open and/or shared on the network, those files may not be usable on restore. You will need to contact your software vendor for specific file backup and recovery procedures. There are software packages and services available for most popular applications that can recover most or all data from applications that were improperly backed up while in an on-line state.
This would be the same if you attempted to back up an on-line MS SQL database file directly and did not use (or have licensed) the DPX SQL backup component. Backing up the binary image of the data file would be successful, however since the database is open and in use, it is not guaranteed (by Microsoft) to be usable for a system restore.