There isn't a lot of generic documentation on this - most
recommendations are specific to the type of storage your system is
using.

However:  I generally prefer to have 1 container per physical storage
device (individual disk or RAID array), using DB2_PARALLEL_IO when
appropriate.

With large RAID arrays and SAN storage, you do have to be careful
because you may have multiple LUNs that reside on the same RAID array.
Putting 1 container/LUN when you have multiple LUNs from a single
RAID array can create I/O contention issues.

From a performance and parallelism viewpoint, multiple containers can
be of benefit if each container is located on a separate disk drive.
This allows parallel I/O when doing scans.

If you place two containers on a single disk drive, then, as data is
read from each container, a seek operation will be needed. Seeks are a
relatively slow operation and should be avoided as much as possible when
doing scans. When containers are located on separate disks, we expect to
read data from each disk drive in turn. If the system has the capacity
to do this concurrently from multiple drives, then the overall transfer
rate can be significantly improved.

Large raid5 disk subsystems, while using multiple disk drives, appear to
the operating system as a single disk. Placing multiple containers on
these doesn't provide the same benefits as separate disk drives will.
Raid5 can, with judicious matching of prefetch parameters to the
physical characteristics of the raid array, provide scan performance
enhancements similar to using multiple containers on different physical
disk drives.

Suggested reading:
Administration Guide: Planning  - Chapter 5

Phil Sherman