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Oracle Tips by Burleson |
Older technology can be very
dangerous
This concept is important because many enterprises may inadvertently
double cache Oracle data. Even more problematic are the fake
statistics reported by Oracle when multiple level caches are
employed:
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Fake Physical I/O times: When using a
disk array with a built-in RAM cache, the disk I/O subsystem may
acknowledge a physical write to Oracle when, in reality, the
data has not yet been written to the physical disk spindle. This
can skew timing of disk read/write speed.
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Wasted Oracle Data Buffer RAM: In
systems that employ web servers, the Apache front end may cache
frequently used data. Hence, significant Oracle resources may be
wasted caching data blocks that are already cached on the web
server tier.
The above book excerpt is from:
Oracle RAC
& Grid Tuning with Solid State Disk
Expert Secrets for High Performance Clustered Grid Computing
ISBN:
0-9761573-5-7
Mike Ault, Donald K. Burleson
http://www.rampant-books.com/book_2005_2_rac_ssd_tuning.htm |
