RAID-0+1
Combines the one-to-one mirroring of RAID-1 with the striping of RAID-0.
RAID-3
Provides redundancy by storing parity information on a single disk in the array.
This parity information can help to recover the data on other disks, should they
fail. RAID-3 saves on disk storage compared to RAID-1, but isn??™t often used
because the parity disk can be a bottleneck.
RAID-5
Uses parity data for redundancy in a way that is similar to RAID-3, but stripes the
parity data across all of the disks, like the way in which the actual data is striped.
This alleviates the bottleneck on the parity disk.
There are additional levels of RAID, including RAID-6, which adds dual parity data,
and RAID-7 and RAID-8, which add performance enhancements to the characteristics
of RAID-5.
164 | Chapter 7: Oracle Performance
Instead, suppose you placed the same datafile on a ???disk??? that was actually an array
of five physical disks. Each physical disk in the array can perform I/O operations
independently on different data blocks of the index, automatically increasing the
amount of I/O Oracle can perform without causing contention.
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