Recovering the DS-System database
The DS-System is configured to perform a full database backup every day. Under extreme conditions, you might need to recover the DS-System database. In case of a hard disk failure (either the disk holding the data or the disk holding the log files), there are 2 scenarios:
If the disk holding the log files fails:
1. Perform a full backup of the DS-System database (data files) immediately.
2. Replace the failed disk.
If the disk holding the data files fails:
The database could be restored to the state it was at the point of failure if the current transaction log file for the database is available and undamaged. To restore the database as it was at the point of failure:
1. Back up the current active transaction log.
2. Replace the failed disk.
3. Restore the most recent backup of DS-System database without recovering the database.
4. If you perform other backups between two consecutive daily backups, perform the following steps:
• If differential backups exist, restore the most recent one.
• Restore each transaction log backup created since the database or differential backup in the same sequence in which they were created without recovering the database.
5. Apply the most recent log backup and recover the database.
If you restore from an older DS-System database dump, the following issues will apply:
1. New or modified DS-Client and customer information since the dump time will be lost.
2. Activity logs and event logs since the dump time will be lost.
3. Reports since the dump time will be lost.
4. Potential libraries information since the dump time is lost. Libraries might not get reused and new library creation will take longer for some library files.
5. Invalid library links may in some extreme situations even prevent synchronization of backup sets and this means no backup or restore for that particular set until the links are manually fixed.
6. Used libraries may be marked as unused in the restore database. The Clean Library process will delete these files and restore of data will fail for those files. This error will not be detected during the next backup. To fix this problem, run a full System Admin.
7. New library numbers will start with the last ID found in the database, potentially overwriting existing libraries and rendering restored data useless.
While the loss of information described above from 1-5 does not affect the online files, the last issue (7) would result in overwriting valid files with different new ones. Restoring files linked to such libraries will retrieve completely different files and will fail because of a different signature, encryption or compression.
To address this problem, whenever DS-System database is restored from an older dump, the information in the database must be updated with the current online storage before anything else. This process will add records into the database for all libraries created after the dump. This synchronization is triggered when the DS-System service starts, if there is a negative value in the db_number field from the ds_data table in the dssystem database. For example if db_number has a value of 231, change it to –231.
Whenever you restore a DS-System database dump, before starting the DS-System service, make sure that you run the latest installation to apply all the latest database patches, and make sure that the db_number field from the ds_data table in the dssystem database is negative.
It is recommended that you run a full System Admin as soon as the DS-System service starts.