I/O tuning

Disk Input/Output is the main bottleneck in a computer system. Since access from disk is 1000 times slower than memory, we must ensure maximum response.

The first thing we should discuss is transaction logs . Best practices in the industry recommend a separate, local, physical disk dedicated to this task, or ideally a RAID 1 configuration. Since DB2 writes to transaction logs in append mode, having a dedicated disk ensures that the write head is always ready to write without needing seek time.

The second thing to discuss is your debugging. Make sure the diagnostic logs are separated from the data. If you have event monitoring turned on, make sure it is separated from your tables and indexes. All explain plan tables (EXPLAIN.DDL) should follow the same rule.

The third thing to discuss is the number of spindles available for the database. In the case of RAID storage, or for individual drives, the rule of thumb is to configure at least 10 to 20 disks, per processor.

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