Restoring the System Databases

The recovery procedure for system databases depends on the database involved and the system problems that necessitated the recovery..

In general, recovery may include:

Using load database to load backups of these databases,
Using sybrestore to restore an SAP ASE database to the time of failure from the most current full database backup dump files.
Using dataserver, installmaster, and installmodel to restore the initial state of these databases, or
A combination these tasks.

To make the recovery of system databases as efficient as possible:

Do not store user databases or any databases other than master, tempdb, model, and sybsystemdb on the master device.
Always keep up-to-date printouts of important system tables.
Always back up the master database after performing actions such as initializing database devices, creating or altering databases, or adding new server logins.

Special procedures are needed because of the central, controlling nature of the master database and the master device.

Tables in master configure and control all SAP ASE functions, databases, and data devices. The recovery process:

Rebuilds the master device to its default state when you first installed a server
Restores the master database to the default state
Restores the master database to its condition at the time of your last backup

During the early stages of recovering the master database, you cannot use the system stored procedures.

Recovering the master Database
A damaged master database can be caused by a media failure in the area on which master is stored, or by internal corruption in the database.
Recovering the model Database
Use dataserver to restore the model database without affecting master.
Recovering the sybsystemprocs Database
The sybsystemprocs database stores the system procedures that are used to modify and report on system tables.
Reducing the Size of tempdb
The tempdb (temporary) database provides storage for temporary tables and other temporary working storage needs. If you have a corrupted disk that contains portions of tempdb, you should first reduce tempdb to its default size and then extend it onto any new device.
Restoring System Tables with disk reinit and disk refit
When you are restoring the master database from a dump that does not reflect the most recent disk init or create database and alter database commands, restore the proper information in the sysusages, sysdatabases, and sysdevices tables.