Storage Devices for Logical-Log Backup (ON-Bar) 

Consider the following when planning the storage devices (for example, tape drives) for logical-log backup of your Informix database with ON-Bar :

You need to define at least the device LTAPEDEV with a suitable physical device. Refer to Configuring ON-Bar.

Do not use /dev/null (UNIX) or nul (NT) for LTAPEDEV if you want to perform a restore of your system up to the time of failure.

ON-Bar does not use LTAPEDEV to specify the storage device for logical-log backup. However, if you specify a null value for LTAPEDEV , the logical-log files are marked as "backed up" as soon as they are full. Therefore, they cannot be backed up and the transactions recorded in these logs cannot be used for a logical restore.

SAP recommends that you have at least two storage devices, one for database backups and one for logical-log backups. Otherwise, if your logical logs fill up when you are performing an archive, the database might stop processing. At the minimum, you must have one storage device (that is, drive) for logical-log backup.

Your devices must be fast enough to cope with the maximum rate at which the logical log fills. Your devices must also accept storage media with sufficient capacity for your logical-log backups. Local devices are more likely to cope than remote devices.

For continuous logical-log backup, you must dedicate a storage device to the logical-log backup. SAP recommends you to use a local device for logical-log backup because the performance is better than with a remote device.

Since the storage manager – for example, Informix Storage Manager (ISM) – handles logical-log backup with ON-Bar , you need to make sure that it is correctly set up and communicating with the storage devices. For more information, see your storage manager documentation.

 

See also:

Informix documentation