Network Registrar Backup

To ensure a consistent snapshot of the Network Registrar database, Network Registrar provides a shadow backup facility.

Backing Up the Database

Because the Network Registrar database (called MCD) does a variety of memory caching and may be active at any time, you cannot rely on doing system backups to protect the data in the database. At the time you run a system backup, there may be Network Registrar operations in progress that cause the data copied to the system backup tape to be inconsistent, and unusable as a replacement database.

To ensure a consistent backup, Network Registrar uses a shadow backup facility. Once a day, at a configurable time, Network Registrar suspends all activity to the database, and takes a snapshot of the critical files. This snapshot is guaranteed to be a consistent view of the database, and it will be preserved correctly on a system backup tape. This backup is only a single generation backup. To maintain multiple backup versions, implement an archiving strategy.

Note Network Registrar backs up the DNS data even when the shadow backup is run on a secondary server.

Configuration

The only configuration for this facility is through a single entry in the system Registry.

For Windows NT, the registry path to this item is as follows:

: HKEY_LOCAL_MACHINE/SOFTWARE/American Internet/NetworkRegistrar/2.0/DBShadowTime

For UNIX, the registry path to this item is as follows:

: /opt/nwreg2/conf/aic.conf

This entry is a string that represents the time-of-day at which the shadow backup is scheduled to occur (in 24 hour HH:MM format). The default is 23:45.

If you remove this Registry entry or set it to an illegal value (for example, anything that does not begin with a digit), you will suppress the backups. The server is otherwise unaffected.

Command-Line Utility

In addition to being available at a scheduled time of day, you can also force a shadow backup by using the mcdshadow utility located in the \Program Files\Network Registrar\bin directory for Windows NT or the /opt/nwreg2/bin directory for UNIX. There are no command-line arguments. Type mcdshadow to cause Network Registrar to perform the shadow backup.

Because a full copy of the database is created, this may take a few minutes to complete.

Recovery

Use the shadow backup to recover data, either because the regular working database has been corrupted by a system crash or because the disk on which it resides has become corrupted.

Step 1 Stop all Network Registrar servers.

Step 2 Make sure that there are three files in \Program Files\Network Registrar\data\db.bak (Windows NT) or /var/nwreg2/data/db (UNIX).

The files are mcddb.d01, mcddb.d02, and mcddb.d03.

Step 3 Copy them into \Program Files\Network Registrar\data\db (Windows NT) or /var/nwreg2/data/db (UNIX). Do not move them because they may be needed again.

Step 4 Change the directory to \Program Files\Network Registrar\data\db (Windows NT) or /var/nwreg2/data/db (UNIX).

Step 5 Rebuild the key files by typing the command ..\..\bin\keybuild mcddb (Windows NT) or /opt/nwreg2/keybuild mcddb (UNIX).

This can take several minutes.

Step 6 As a safety check, type the command ..\..\bin\dbcheck mcddb (Windows NT) or /opt/nwreg2/dbcheck mcddb (UNIX) to verify the integrity of the database.

Note

dbcheck

You should have no errors.

Mcdshadow Files

The mcdshadow command uses the files listed in Table G-1.

Table G-1: Mcdshadow Files

File Description

mcddb.dbd

Template file that describes the low-level data schema for the Raima runtime library.

mcddb.k01-k03

Key files that contain the data that is redundant with the data files. Network Registrar does not back up these files because they can be completely rebuilt with the keybuild command.

mcdcd.d01-d03

Data files that contain the backup.

mcdConfig.txt

Text file from which Network Registrar configures the initial at-install-time database.

mcdschema.txt

Text file that contains a version number denoting the level of the schema contained in the dbd file. Network Registrar will not attempt to open the database unless the number in this file matches a constant that is hard-coded in the libraries. If the result of the mcdshadow (which it just copies of the data files) is divorced from its original mcdschema.txt, you will not be able to run Network Registrar.

vista.taf, tcf, tjf

Working files used by the Raima runtime to ensure transactional integrity.

File	Description
mcddb.dbd	Template file that describes the low-level data schema for the Raima runtime library.
mcddb.k01-k03	Key files that contain the data that is redundant with the data files. Network Registrar does not back up these files because they can be completely rebuilt with the keybuild command.
mcdcd.d01-d03	Data files that contain the backup.
mcdConfig.txt	Text file from which Network Registrar configures the initial at-install-time database.
mcdschema.txt	Text file that contains a version number denoting the level of the schema contained in the dbd file. Network Registrar will not attempt to open the database unless the number in this file matches a constant that is hard-coded in the libraries. If the result of the mcdshadow (which it just copies of the data files) is divorced from its original mcdschema.txt, you will not be able to run Network Registrar.
vista.taf, tcf, tjf	Working files used by the Raima runtime to ensure transactional integrity.

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