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Oracle Database Tips by Donald Burleson
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Solid-State Disk with Oracle
Today's world is one of constantly improving
hardware technology. Yesterday's mainframe is today's PC, and there
are 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 as shown in 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 where 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 achieve tertiary storage with software mechanisms that
write the RAM frames to a back end disk on the device.
With the cost of SSD at only $1k/gig, many Oracle
RAC 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 a 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 left
users with duplicate cache areas such as web cache, Oracle buffer
cache, on-board disk cache, etc., and it is now the challenge of the
Oracle DBA to exploit SSD for the most benefit for their database
application.
This benchmark information will include the
following sections:
-
There is a huge debate about the effect of data caching, with many
opposing theories and conflicting research results. This section
will take an objective look at the caching issue for Oracle
databases.
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This section will predict what the Oracle SSD TPC-C benchmark on RAC
might reveal and justify the basis for the choice of testing
scenarios.
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This section describes the TPC-C
database environment and hardware choices.
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This section contains the results for 21 tests.
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This section compares predicted results with the associated
hypothesis. The results will be extrapolated, and the benefits of
SSD for specific types of Oracle database systems will be
generalized.
The following section will introduce the current
state of SSD research.
See
code depot for complete scripts
This is an excerpt from the book
Oracle RAC & Tuning with Solid State Disk.
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
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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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