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Configuring the System
In Different Levels of Data Protection, the various levels of data security are described.
When you configure your system, some additional considerations are:
- How do I divide the work load over several disks to get the best performance?
TRANSDB and its shadows should preferably be on fast disks, see Performance Aspects of Shadowing.
- How much disk space is required?
A shadow file occupies the same amount of disk space as the master databank file.
A problem occurs if TRANSDB or LOGDB run out of disk space. When this happens the system cannot continue. Therefore, it is important to make sure that there is enough space for these databanks.
How large LOGDB grows depends on whether the LOG option is used and how often backups are taken and drop log is performed, since drop log clears LOGDB and releases space (but the file size remain unchanged).
How large TRANSDB grows depends on the number of transactions and how fast the shadow servers are able to perform the transactions on the shadows. When the transactions are performed on the shadows, the space in TRANSDB where they were stored is released.
- How long does a backup on the fly take?
During a backup on the fly one or more shadows are set offline, and transactions are buffered in TRANSDB. How large TRANSDB grows depends on the amount of time needed to backup the databanks, and the frequency of the transactions on the databanks with offline shadows.
 Upright Database Technology AB Voice: +46 18 780 92 00 Fax: +46 18 780 92 40 dbtechnology@upright.se |
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