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Implementing the appropriate hardware, operating system, or database features can improve the availability of a database instance. Note the following points:

·        Every volume type should be located on a different disk.

·        In a production system, the log area should always be mirrored with hardware-based tools. Use RAID 5 or RAID 1 systems. Make sure that your RAID controller delivers good write performance, and that a cache is backed up to the disk even in a power outage.

·        If you cannot use hardware-based mirroring, then you can set the log mode of the database instance so that it uses software-based mirroring.

·        Use normal log backups. This means that the log area cannot be overwritten.

Note

To make sure that you always have enough space to write the log entries, make regular log backups.

·        Always activate redo log management.

·        If you want to ensure a high standard of availability, we recommend using RAID-5 or RAID-1 configurations for the data area. A disk crash and change will then not affect the running of the database, if the RAID system is able to carry out a restore.

·        In a production system on UNIX, data volumes and log volumes should be used in conjunction with raw devices. Raw devices achieve better performance, and are more secure in the event of a system failure.

·        When using fault-tolerant hardware, it is best to only use the same type of hardware when you want to extend the capacity. For example, RAID-5 systems should only be extended using RAID-5 systems and mirroring disks with mirroring disks.

 

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