We just got through talking with Oracle about this. In essense, the
redo logs are not performance orientated. For SANs, everything should
be stripped. EMC Hypers and Hitachi LDEVs start life preallocated as
stripes across disks. Anyway, the redo logs though can be placed on
lower tier storage, such as a nearstore precisely because they are for
the event of recovering a database and therefore have no performance
impact on production data. Redo logs are a good example of what can
use tiered storage models.

Either way, you will want them to be on a seperate storage device
because of the nature. They would be used in the event that your
primary storage fails. You'd want to make sure that they were at
least on a different set of disks on the SAN. Ideally, they should be
on a seperate device all together. RAID storage can fail, and you
don't want to loose your redo logs as well as your primary data.