Describes several failure scenarios (using the Sample Backup and Recovery Plan setup), how recovery works, and implications for Sybase Unwired Platform operation.
Disk C has an unrecoverable error. The *.db files have been lost.
Recovery: - Make sure you have current backups of *.db and *.log files; in this scenario they are on Computer B.
- Install a replacement disk, and use the Sybase Unwired Platform runtime installer to reinstall the data tier. This restores the embedded SQL Anywhere software, used as the cache database for synchronization.
- Restore the database *.db files, by copying the last backup version of the files from Computer B.
Restore the transaction *.log files.
If you are restoring a single log, you can use the -a option, using a command similar to:
dbeng<sqlAnywhere version> <path>default.db -a <restored_path>default.log
Note: See Supported Hardware and Software for supported SQL Anywhere versions embedded with Sybase Unwired Platform.
If you are restoring multiple transaction logs, they must be started in the correct order, otherwise, the database does not start. You can use the -ad or -ar option in your command to automatically apply multiple transaction logs in the correct order, using a command similar to:
dbeng<sqlAnywhere version> <path>default.db -ad <restored_path>default.log
In either case, see the SQL Anywhere documentation for information about composing commands to restore transaction logs. O.
- Start Unwired Server, which restarts SQL Anywhere and detects that the *.db files are not up-to-date with the checkpoints in the *.log files on drives D: and E: (which are unaffected by the C: drive failure). The server automatically replays transactions recorded in the transaction log to bring the database back to the state of all committed transactions at the time of the C: drive failure.
Sybase Unwired Platform can then start up and run normally. Sybase Unwired Platform mobile device clients are not affected except by the inability to synchronize between the time of the failure, and the time at which the recovery process has completed.
Disk D: or E: failure. One of the *.log files has been lost.
Recovery: Install a replacement disk and restore from backups.
Once the disk has been restored, copy the *.log files from the drive that did not fail to the one that failed. Restart the failed drive.
Complete failure of Computer A, and disks lost.
Recovery: See Restoration of the Runtime Database for information. This should be a very infrequent event.
In this scenario, the database has lost all transactions since the previous backup to Computer B. Any Sybase Unwired Platform mobile device clients that synchronized between the time of the previous backup and the time of the failure cannot now sync. Clients must delete their remote device client database and start fresh. Any pending operations on these clients are lost. Clients that have not synchronized since the previous backup are unaffected.