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Oracle Database Tips by Donald Burleson
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Comparing
the Different Scenarios
The main focus for testing was determining the raw
performance of SSD verses disk technology. The following is a list of
the scenarios tested:
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SSD performance with the DSS type queries with no
logging and no archive logging
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SSD Performance with the DSS type queries with logging
and archive logging
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Regular Disk Performance for DSS type queries with no
logging and no archive logging
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Regular Disk performance for DSS type queries with NL
and NAL and temporary and undo segments on SSD
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Regular disk performance for DSS type queries with NL
and NAL and data on the SSD
-
Regular disk performance for DSS type queries with NL
and NAL and memory reduced.
The SSD scenarios will be
examined first to determine what conclusions can be reached.
SSD Scenario Comparisons
Overall SSD performance was uniform with the
exception of the initial run when memory areas used in later queries
where being loaded. Assuming that the data loaded and then read from
Oracle memory structures was nearly identical for each set of
identical queries with identical initialization parameters, the SSD
outperformed the regular disks for DSS queries by at least two orders
of magnitude.
In comparing the total time for all queries to
complete, the SSD database out performed the normal disk databases by
a minimum factor of 179. Recall that several of the normal disk
queries had to be halted at the 24 hour point in order to be able to
complete the query runs in a reasonable amount of time. Therefore the
true magnitude of the difference in times between the SSD and normal
disk runs is technically much higher. Table 4.1 (above) lists the
results form the 7 SSD runs.
Disregarding runs that followed a database
restart, the performances across the various scenarios were within a
couple of percent of each other. Runs 1 and 7 both followed restarts
and also showed comparable results. Documented research exists that
indicates that these results will hold even with multi-user access.
The reason being that no disk latency, read blocking, or other disk
access issues are encountered with SSD technology. In fact, until the
I/O channels get flooded, all users should experience similar
performance. With proper configuration, transfer rates of up to 2
gigabytes per second are possible using SSD technology.
While some queries required up to 10 minutes to
achieve results on the SSD array, this was still substantially less
time than the same queries required on either the SCSI or ATA arrays.
Since some of the SCSI and ATA queries never finished within the
boundaries of our test configurations, it is not possible to know how
long they would have taken. Now the SCSI and ATA scenarios will be
examined.
See
code depot for complete scripts
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
|
PCIe
|
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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