High IO waits if all that is waiting is
the archive writer and/or log writer is
not necessarily a problem. These are I/O
intensive and will be waiting for I/O most
of the time they are running. Likewise,
for backups, cp, mv, etc.
Is the load average high (more than 2* CPUs)?
If not you likely don't have a problem.
If the database has too small an SGA, then
you may have high read io on the database.
Default SGA is usually very small. Try
increasing the SGA and see if IO goes down.
Try running 'sar -D' to see which disks
and partitions have the IO occurring.
It will also so the read/write balance.
Once the database has been running for a
while frequently accessed data should be
in cache. You should see relatively little
read activity on the partions with your
tablespaces.
If you have heavy tablescanning of large
tables, then you may see high read IO, if
the SGA is too small to cache the tables.
If you are in archive log mode, you should
see periodic heavy read activity on the
partition with a log file with corresponding
write activity on the partition with your
archived redo logs.
