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This section
of the APL website provides information about equipment that is
suitable for use with SCRATCH®. It will enable you to choose
vendors that are capable of providing qualified components for a
working solution. It is important to understand that all components
are interdependent and should not be treated in isolation.
For example, while storage may be fast enough to support the I/O
requirements of SCRATCH, this is only one factor in providing a
suitable solution. The amount of RAM, speed and number of the processor(s)
in the Host
Workstation, as well as the type of Graphics
Card used, all determine the suitability of a configuration
to run SCRATCH. To receive guidance with these issues, please refer
to the relevant pages in this section of the APL website.
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What are the performance requirements for storage that is suitable
for SCRATCH?
The two deciding factors when judging the performance of a storage
system are the latency (how quickly can the data be accessed) and
bandwidth (how much data can be transported from the disks to the
computer.
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The performance requirements listed below are based on a file-size
of approximately 12MB per frame, which equals a 10bit log DPX file
at 2048x1556 pixels resolution (referred to from now on in as 2k):
a)
For 25fps playback of 2k 10bit DPX files the technical minimums
are:
- 25 guaranteed
I/O transactions per second for a total request size of 12MB per
transaction
- Minimum latency
per I/O better than 40ms
- Sustained
read bandwidth across array, minimum of 301MB/s
- This is the
absolute minimum that MUST BE sustained at all times.
b)
For dual stream 24fps playback
of 2k 10bit DPX files:
- 48 guaranteed
I/O transactions per second for a total request size of 8.4 to
12MB per transaction
- Minimum latency
per I/O better than 20ms
- Sustained
bandwidth across array for dual stream operation at 24fps per
stream, minimum of 577MB/s
The performance
of suitable direct-attached arrays for SCRATCH will usually lie
somewhere in between these two boundaries [of a) and b)], whereas
SANs may often exceed this performance envelope. The smaller request
size of 8.4MB is roughly the size of a Super2k DPX frame (2048x1080
at 10 bit log). While Super2k will be easier on the bandwidth requirements;
it will still require full I/O transaction performance. Sustaining
these I/O transactions tends to be more of a problem for SATA arrays
at this point.
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What is the APL benchmark configuration and where are the
results?
In order to provide a standardized basis for comparison of a diverse
range of storage solutions, APL offers a benchmark configuration
that closely reflects the demands placed on a system when running
SCRATCH in a 2k DI workflow. All test results submitted to this
site must use this benchmark configuration in order to be published.
If you are looking for products that have already been tested with
the APL benchmark configuration, you can review the results submitted
by various vendors using the APL benchmark specification here.
Please note that these results are not absolute in their nature
and merely designed to provide a decision making tool to assess
the suitability of a storage solution with SCRATCH.
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Feel like testing a storage system yourself? What are my
options?
a) Use the APL benchmark configuration
The APL benchmark configuration for use with the I/Ometer software
is available from the Vendor section of this site. The Vendor
section of APL also provides detailed instructions on how to go
through the benchmarking procedure.
b) Run Scratch for real
You may also wish to request a demo version of SCRATCH by emailing
our sales team at . This option will provide you with a first hand
experience of the expected performance of your hardware. Please
ensure that your workstation
is equipped with a supported graphics
card.
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Should you be unsure about the requirements or procedures,
or require advice, email apl@assimilateinc.com
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