Is there an optimal size for RAID-5 log disks. I have a system with 11
RAID-5 volumes each one of which has a log plex associated with it. The log
plexes are not very big, about 8Mb each, but they all reside on the same
physical disk. We are experiencing some I/O performance problems with the
system and I was wondering if the log disks were maybe too small because I
have noticed that sometimes the system tries to write about 20Mb of log
data. Would performance improve if I spread the log subdisks out over
several physical disks rather than have them all on one.

The system was originally intended to be a data warehouse, hence the use of
RAID-5, but in the real world we find that the customer is making lots of
big writes to it whilst uploading data. I also have an exercise going to
determine which tablespaces in the database are written to most with a view
to putting them on a simple striped mirror.