EXPERT RESPONSE
The answer all depends on your RAID level. If you
implement mirroring (RAID 1), then competing reads and
writes can work off one mirror while the other I/O
operation uses the other mirror. But this all depends
on the vendor's implementation of RAID 1. RAID 3 and 5
use striping which lets multiple disk volumes spread
out the workload. But RAID 3 and 5 introduce a write
penalty to compute parity bits. So write operations
can be slower in RAID 3 and RAID 5 environments.
Many RAID systems are implemented in Storage Area
Networks (SANs) which use disk caching. In these
cases, disk reads and writes can be very fast.
There are many factors that contribute to the
performance success of RAID for Oracle databases.
Stripe size, disk speed, disk connection architecture,
mirroring. In the end, your mileage may vary due to
your configuration. So testing is of utmost importance
in deciding which RAID level, if any, to use.
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