Using Continuous Operations

Continuous Operations provides the ability to backup data files while database applications are running and users are connected. However, in the event of a hard drive failure, if you use Continuous Operations to make backups, you will lose all changes to your data since the last backup. You cannot use Archival Logging and the Maintenance utility Roll Forward command to restore changes to your data files that occurred after the last backup.

Pervasive.SQL provides a backup command, BUTIL, for Continuous Operations.

This section is divided into the following sub-topics:

Starting and Ending Continuous Operations

Backing Up a Database with BUTIL

Restoring Data Files when Using Continuous Operations

Starting and Ending Continuous Operations

This section provides detailed information on the commands: STARTBU and ENDBU.

Table 8-5 Commands to Start and Stop Continuous Operation
Command	Description
STARTBU	Starts continuous operation on files defined for backup (BUTIL).
ENDBU	Ends continuous operation on data files defined for backup. (BUTIL).

Note
The temporary delta files created by Continuous Operations mode have the same name as the corresponding data files but use the extension ".^^^" instead. Therefore, do not create multiple data files with the same names but different extensions. For example, do not use a naming scheme such as INVOICE.HDR and INVOICE.DET for your data files. If you do, the MicroKernel returns status 85 and no files will be put in Continuous Operations.

Continuous operation mode does not significantly affect MicroKernel performance; however, using a server to back up files can affect performance.

To protect against data loss using Continuous Operation

Use the -STARTBU command to put your files in continuous operation. See STARTBU for an explanation of the command syntax with BUTIL.

Back up your data files.

Use the -ENDBU command to take your files out of continuous operation. See ENDBU for an explanation of the command syntax with BUTIL.

Backing Up a Database with BUTIL

This section provides detailed information on backing up a database using the following BUTIL commands: STARTBU and ENDBU.

STARTBU

The BUTIL -STARTBU command places a file or set of files into continuous operation for backup purposes.

Format

BUTIL -STARTBU <sourceFile | @listFile> [/S]


sourceFile	The fully qualified name of the data file (including the drive specification for Windows 32-bit platforms and volume specification for NetWare) on which to begin continuous operation for backup. This fully qualified name must reside on the same machine as the one from which you are running butil. You cannot used mapped drives with the startbu command.
listFile	The name of a text file containing the fully qualified names of files on which to begin continuous operation. Separate these file names with a carriage return/line feed. (Although the utility accepts a blank space separator as well, future versions of Pervasive.SQL may accept blank characters in file names. For compatibility with future versions of Pervasive.SQL, use the carriage return/line feed separator.)If the Maintenance utility cannot put all of the specified files in continuous operation, the utility does not put any of the files in continuous operation.
/S (NetWare only)	By default, the Maintenance utility stops at each full screen of output and waits for a keystroke before continuing. With the /S option, the utility continuously scrolls output on the screen. You cannot use /S on the command line if you specify a command file, but you can specify /S with a command inside a command file.

 
 


 Note


This command begins continuous operation only on the files you specify. You cannot use wildcard characters with the STARTBU command.

Examples for Windows Server

Example A The first example starts continuous operation on the COURSE.MKD file.

For Windows Server:

butil -startbu c:\pvsw\demodata\course.mkd

Example B The following example starts continuous operation on all files listed in the STARTLST.FIL file.

butil -startbu @startlst.fil

The STARTLST.FIL file might consist of the following entries:

c:\pvsw\demodata\course.mkd 
c:\pvsw\demodata\tuition.mkd 
c:\pvsw\demodata\dept.mkd

Examples for NetWare Server

Example A The first example starts continuous operation on the COURSE.MKD file.

butil -startbu sys:\pvsw\demodata\course.mkd

Example B The following example starts continuous operation on all files listed in the STARTLST.FIL file.

butil -startbu @sys:\test\startlst.fil

The STARTLST.FIL file might consist of the following entries:

sys:\pvsw\demodata\course.mkd 
sys:\pvsw\demodata\tuition.mkd 
sys:\pvsw\demodata\dept.mkd

ENDBU

The ENDBU command ends continuous operation on a data file or set of data files previously defined for backup. Issue this command after using the STARTBU command to begin continuous operation and after performing your backup.

Format

BUTIL -ENDBU </A | sourceFile | @listFile> [/S]


/A	If you specify `/A`, the utility stops continuous operation on all data files initialized by BUTIL -STARTBU and currently running in continuous operation mode.
sourceFile	The fully qualified name of the data file (including the drive specification for Windows 32-bit platforms and volume specification for NetWare) for which to end continuous operation. This fully qualified name must reside on the same machine as the one from which you are running butil. You cannot used mapped drives with the endbu command.
@listFile	The name of a text file containing a list of data files for which to end continuous operation. The text file must contain the fully qualified file name for each data file, and you must separate these file names with a carriage return/line feed. (Although the utility accepts a blank space separator as well, future versions of Pervasive.SQL may accept blank characters in file names. For compatibility with future versions of Pervasive.SQL, use the carriage return/line feed separator.)Typically, this list of data files is the same as the list used with the STARTBU command.
/S (NetWare only)	By default, the Maintenance utility stops at each full screen of output and waits for a keystroke before continuing. With the /S option, the utility continuously scrolls output on the screen. You cannot use /S on the command line if you specify a command file, but you can specify /S with a command inside a command file.

Example for Windows Server

The following example ends continuous operation on the COURSE.MKD file.

butil -endbu c:\pvsw\demodata\course.mkd

However, you can also just enter butil -endbu course.mkd instead of the full path if your current directory is f:\demodata.

Example for NetWare Server

The following example ends continuous operation on the COURSE.MKD file.

butil -endbu sys:\pvsw\demodata\course.mkd

Restoring Data Files when Using Continuous Operations

If you are using Continuous Operations for your backup strategy, then you have no recovery log that can be used to recover changes since your last backup. All database changes since your last backup are lost, with the possible exception of any transactions stored in the transaction log. Any such transactions are automatically rolled forward by the database engine when it starts up.

To restore data and normal database operations

Resolve the failure.

Perform the maintenance required to make the failed computer operational again.

Restore the data files from backup, or restore the hard drive image from backup, as appropriate.

Re-install Pervasive.SQL if it was not restored as part of a disk image.

Re-start the database engine.

Any database operations performed since the last backup must be performed over again.