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Oracle Database Tips by Donald Burleson
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Judging Solid-State Disk with Oracle
As a result of living in a world of constantly
improving hardware technology, yesterday's mainframe is today's PC.
There have been unprecedented improvements to the speed and cost of
computer hardware. Moore's Law
dictates that hardware costs will constantly fall while prices become
constantly cheaper (Figure 1.1).
This rapid change is especially evident for Random
Access Memory (RAM). Using RAM memory is critical to the performance
of today's database management systems because RAM speed (expressed in
nanoseconds) is more than 10,000 times faster than traditional disk
storage device speed (expressed in milliseconds). RAM allows data to
be accessed far faster than disk technology, and I/O-bound Oracle
systems will soon be able to benefit from RAM like never before.
The latest incarnation of RAM storage devices are
the solid-state disk (SSD) technology. With SSD the ancient spinning
platters of magnetic-coated media are replaced with an array of
super-fast solid-state RAM. Just like disks were backed-up to tape,
today's SSD devices write the RAM frames to a back-end disk with
software.
With the cost of SSD at only $1,000 per gigabyte,
many Oracle systems are exploring how to leverage this powerful
performance tool for their environment. Smaller databases can now run
fully-cached with SSD, yet there is debate about the proper use of SSD
in an Oracle environment.
The proper use of SSD is the central question for
this benchmark. Traditional architectures of the 1990's have resulted
in duplicate cache areas. For example, web cache, Oracle buffer
cache, and on-board disk cache. Now the challenge of the Oracle DBA is
to exploit SSD to benefit their database applications.
In the following sections these topics will be
covered:
- There is an ongoing debate about the
effect of data caching, resulting in many opposing theories and
conflicting research results. This section will take an objective
look at the caching issue for Oracle databases.
- This section will predict what the Oracle SSD benchmark might reveal
and justify the basis for the choices of testing scenarios.
- Describes the Transaction Processing Performance Council(TPC) database environment and
the choice of hardware. Complete details are presented in Appendix A.
- This section contains the test
results.
- This section will compare the predicted results with the
hypothesis. It also includes an extrapolation of the results and
generalizes the benefits of SSD for specific types of Oracle database
systems.
This is an excerpt from the book
Oracle
Solid State Disk Tuning.
You can get it for more than 30% by buying it directly from the
publisher and get immediate access to working code examples.
Market Survey of SSD vendors for
Oracle:
There are many vendors who offer rack-mount solid-state disk that
work with Oracle databases, and the competitive market ensures that
product offerings will continuously improve while prices fall.
SearchStorage notes that SSD is will soon replace platter disks and that
hundreds of SSD vendors may enter the market:
"The number of vendors in this category could rise to several
hundred in the next 3 years as enterprise users become more familiar
with the benefits of this type of storage."
As of January 2015, many of the major hardware vendors (including Sun and
EMC) are replacing slow disks with RAM-based disks, and
Sun announced that all
of their large servers will offer SSD.
Here are the major SSD vendors for Oracle databases
(vendors are listed alphabetically):
2008 rack mount SSD Performance Statistics
SearchStorage has done a comprehensive survey of rack mount SSD
vendors, and lists these SSD rack mount vendors, with this showing the
fastest rack-mount SSD devices:
| manufacturer |
model |
technology |
interface |
performance metrics and notes |
|
IBM |
RamSan-400 |
RAM SSD |
Fibre
Channel
InfiniBand
|
3,000MB/s random
sustained external throughput, 400,000 random IOPS |
|
Violin Memory |
Violin 1010 |
RAM SSD
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PCIe
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1,400MB/s read,
1,00MB/s write with ×4 PCIe, 3 microseconds latency |
|
Solid Access Technologies |
USSD 200FC |
RAM SSD |
Fibre Channel
SAS
SCSI
|
391MB/s random
sustained read or write per port (full duplex is 719MB/s), with
8 x 4Gbps FC ports aggregated throughput is approx 2,000MB/s,
320,000 IOPS |
|
Curtis |
HyperXCLR R1000 |
RAM SSD |
Fibre Channel
|
197MB/s sustained
R/W transfer rate, 35,000 IOPS |
Choosing the right SSD for Oracle
When evaluating SSD for Oracle databases you need
to consider performance (throughput and response time), reliability (Mean Time Between failures) and
TCO (total cost of ownership). Most SSD vendors will provide a
test RAM disk array for benchmark testing so that you can choose the
vendor who offers the best price/performance ratio.
Burleson Consulting does not partner with any SSD vendors and we
provide independent advice in this constantly-changing market. BC
was one of the earliest adopters of SSD for Oracle and we have been
deploying SSD on Oracle database since 2005 and we have experienced SSD
experts to help any Oracle shop evaluate whether SSD
is right for your application. BC experts can also help you choose
the SSD that is best for your database. Just
call 800-766-1884 or e-mail.:
 for
SSD support details. DRAM SSD
vs. Flash SSD
With all
the talk about the Oracle “flash cache”, it is important to note that there
are two types of SSD, and only DRAM SSD is suitable for Oracle database
storage. The flash type SSD suffers from serious shortcomings, namely
a degradation of access speed over time. At first, Flash SSD is 5
times faster than a platter disk, but after some usage the average read time
becomes far slower than a hard drive. For Oracle, only rack-mounted
DRAM SSD is acceptable for good performance:
|
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Avg. Read speed
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Avg. write speed
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Platter disk
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10.0 ms.
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7.0 ms.
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DRAM SSD
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0.4 ms.
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0.4 ms.
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Flash SSD
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1.7 ms.
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94.5 ms.
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