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Oracle Tips by Burleson |
Analyzing What to Put On SSD
Now that it has been demonstrated that SSD
technology can be a great help to certain types of systems, how does a
DBA determine if internal implementation is warranted? This chapter
will provide insight into the methods used to analyze a system to see
if SSD technology will help.
The choices of what to put on the SSD drive
breakdown into several general areas:
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Data
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Indexes
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Redo logs
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Temporary files
It is more critical to place the above files than
it is files such as control files and archive logs since they do not
generally cause performance issues. Here are some analysis tools to
determine what files should be placed on SSD arrays.
Analysis Tools
Analysis to determine what to place on SSD files
falls under two categories, operating system level analysis and Oracle
internal analysis. Both methods involve analyzing the I/O wait
interface from either the system or Oracle perspective. In many
situations the operating system level analysis may be inconclusive due
to the combining of physical disks into large, RAID combined logical
disks. In this case, look at the I/O to the individual datafiles from
the Oracle perspective.
Inside Oracle there are two areas to look at to
determine the best candidates for placement on the SSD asset. These
two are the I/O statistics and the wait interface statistics. Looking
at the I/O interface for average I/O times and total I/O to specific
datafiles help determine usage patterns for datafiles and temp files.
Looking at the wait interface helps determine if processes are waiting
on I/O related events and what events are being waited on. There are
several possible sources for the I/O and wait interface statistics:
The use of custom scripts gives the analyst
control over the selection and display of specific statistics of
concern. Oracle Enterprise manager provides a plethora of data, but
may not be available at all sites. Third-party tools also provide a
wealth of data but are expensive and may not be installed at all
client sites. STATSPACK reports are available at all sites, provide a
wealth of statistics, and allow a focused look at specific time
intervals. Of the available data gathering methods, scripts and
STATSPACK will be the focus of this chapter. Custom scripts will be
reviewed first for their use in determining the effectiveness of SSD
technology conversion.
The
above book excerpt is from:
Oracle
Solid State Disk Tuning
High Performance Oracle
tuning with RAM disk
ISBN
0-9744486-5-6
Donald K. Burleson & Mike Ault
http://www.rampant-books.com/book_2005_1_ssd.htm
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For more details and scripts, see my new book "
Oracle
Tuning: The Definitive Reference", over 900 pages
of BC's favorite tuning tips & scripts.
You can buy it direct from the publisher for 30%-off and get
instant access to the code depot. |
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