||Oracle Tips by Burleson
Now that the issues surrounding SSD in an Oracle
environment have been covered, one can form a hypothesis about the
results of the benchmark tests.
The central question of this study is to determine
the benefit of SSD for Oracle under these conditions:
This can minimize
PIO with only one physical read into the data buffer, but LIO
overhead will be revealed.
This makes PIO faster but will have repeated LIO overhead as data
blocks are aged out of the Oracle data buffer. The LIO overhead
would be expected to be huge, with high latch contention, buffer
busy waits , and free buffer waits.
duplicating RAM, but it would relieve the LIO issue.
It is now possible to postulate about the
benchmark results. If it is assumed that SSD is far faster for PIO,
the issue of duplicate Oracle activity remains. At PIO time, the
data block must still be read into the
, and then a consistent get is required to deliver
the data block to the requesting program.
RAM resources, therefore, appear to be better
allocated directly to the
using the RAM with SSD.
The above book excerpt is from:
Oracle RAC & Tuning with
Solid State Disk
Expert Secrets for High
Performance Clustered Grid Computing
Donald K. Burleson & Mike Ault