Sybase 12.4.2 Manuale Utente

CHAPTER 12    Managing System Resources

The example above shows disk drive A has two 2GB partitions (a and b) and 
two 500MB (or .5GB) partitions (c and d). There are three other 1GB disk 
drives (E, F, and G). You should create your database on partition a, then add 
dbspaces for E, c, F, b, G and d. 

Using multiple dbspaces allows your IQ and temporary data to be broken down 
into multiple operating system files or partitions. These files can then be spread 
across multiple disks.

Like disk striping, randomness can be created by placing successive database 
files across multiple drives. You can create additional segments for your IQ and 
temporary data with the 

CREATE DBSPACE

 command.

When to create 
dbspaces

When possible, allocate all dbspaces when you create a database. 

If you add dbspaces later, IQ stripes new data across both old and new 
dbspaces. Striping may even out, or it may remain unbalanced, depending on 
the type of updates you have. The number of pages that are “turned over” due 
to versioning has a major impact on whether striping is rebalanced.

The transaction log file contains information that allows Adaptive Server IQ to 
recover from a system failure. Adaptive Server IQ does not use the transaction 
log to restore an IQ database, to recover committed IQ transactions, or to 
restore the Catalog Store for an IQ database. All databases require a transaction 
log.