Follow these guidelines when selecting volume layouts:
Put the database log files on a file system created on a striped and mirrored (RAID-0+1) volume separate from the index or data tablespaces. Stripe multiple devices to create larger volumes if needed. Use mirroring to improve reliability. Do not use VxVM RAID-5 for redo logs.
When normal system availability is acceptable, put the tablespaces on file systems created on striped volumes for most OLTP workloads.
Create striped volumes across at least four disks. Try to stripe across disk controllers. For sequential scans, ensure that the NUM_IOSERVERS and DB2_PARALLEL_IO settings are tuned to match the number of disk devices used in the stripe.
For most workloads, use the default 64 K stripe-unit size for striped volumes and 16 K for RAID-5 volumes.
When system availability is critical, use mirroring for most write-intensive OLTP workloads. Turn on Dirty Region Logging (DRL) to allow fast volume resynchronization in the event of a system crash.
When system availability is critical, use RAID-5 for read-intensive OLTP workloads to improve database performance and availability. Use RAID-5 logs to allow fast volume resynchronization in the event of a system crash.
For most decision support system (DSS) workloads, where sequential scans are common, experiment with different striping strategies and stripe-unit sizes. Put the most frequently accessed tables or tables that are accessed together on separate striped volumes to improve the bandwidth of data transfer.
See About tuning VxVM .