The Emergency Boot Files

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The Emergency Boot Files

The ON–Bar emergency boot files reside in the $INFORMIXDIR/etc directory on UNIX and in the %INFORMIXDIR%\etc directory on Windows. The emergency boot files contain the information that you need to perform a cold restore and are updated after every backup.

ON–Bar must be able to restore objects from a storage manager even when the tables in the sysutils database are not available. During a cold restore, the database server is not available to access sysutils, so ON–Bar obtains the information it needs for the cold restore from the emergency boot file.

Warning:

Do NOT modify the emergency boot file(s) in any way. Doing so may cause ON-Bar to select the wrong backup as part of a restore, possibly leading to data corruption or system failure. Removing or modifying emergency boot file entries for logical log files is particularly discouraged.

Emergency Boot File on Dynamic Server

ON–Bar uses one emergency boot file on Dynamic Server. The filename for the emergency boot file is ixbar.servernum, where servernum is the value of the SERVERNUM configuration parameter.

Emergency Boot Files on Extended Parallel Server

Table 9 lists the types of emergency boot files that Extended Parallel Server uses. Each node with a storage manager contains one backup boot file and one restore boot file. Multiple coservers on a node share a backup boot file and a restore boot file. The database server has one merge boot file.

Use the BAR_BOOT_DIR configuration parameter to specify the location of the emergency boot files. For more information, see BAR_BOOT_DIR (XPS). If you do not specify BAR_BOOT_DIR, the database server stores the boot files in $INFORMIXDIR/etc.

Table 9. Emergency Boot Files
Boot File Type	Boot Filename	Description
Backup	Bixbar_hostname.servernum	This file contains backup information and is updated after every backup.
Restore	Rixbar_hostname.servernum	The onbar-merger process re-creates the restore boot files, which the onbar-worker processes use during a cold restore.
Merge	Mixbar_hostname.servernum	The onbar-merger process re-creates the merge boot file during a cold restore. The merge boot file is temporary and is removed when the onbar_d process that created it exits.

During the cold-restore process, ON–Bar follows these steps to create a restore boot file and restore data.

To create the emergency boot files in a cold restore

It merges the backup boot files from all coservers and creates a merge boot file for the restore.
It distributes the merge boot file to each coserver, renaming it as the restore boot file and overwriting the old restore boot files.
It uses the information in the restore boot file instead of the information in the sysutils database to determine which backup copy of each storage space and log to use.