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I see the numbers, but my instinct says that they can't scale EBS
performance linearly with every EC2 instance they can start. Perhaps
EBS is currently underutilized, so much that the EBS servers are
relatively idle. Once EBS becomes really popular, or if a single large
user runs EBS to many EC2 instances and runs data intensive workloads,
I bet EBS performance will start to suffer (in comparison to local disk
performance). It is certainly an interesting dimension to explore, at
what scale will local disks outperform EBS. <br>
<br>
Ioan<br>
<br>
Tim Freeman wrote:
<blockquote cite="mid:20090512154340.60b88b3d@sietch" type="cite">
<pre wrap="">On Tue, 12 May 2009 15:38:52 -0500
Tim Freeman <a class="moz-txt-link-rfc2396E" href="mailto:tfreeman@mcs.anl.gov"><tfreeman@mcs.anl.gov></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">On Tue, 12 May 2009 15:19:14 -0500
Ioan Raicu <a class="moz-txt-link-rfc2396E" href="mailto:iraicu@cs.uchicago.edu"><iraicu@cs.uchicago.edu></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi Tim,
Tim Freeman wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Is that for speed or less moving parts? I think EBS is the fastest option
they have for disk space (faster than local disk), fyi.
</pre>
</blockquote>
<pre wrap="">Can you elaborate more on how EBS, can be faster than local disk? I know
nothing about EBS, but there are only 2 ways it can work. Since it is
persistent, it likely lives on S3 (or something similar). When it is
mounted, perhaps it still lives remotely, or perhaps it gets copied to a
local disk, and runs locally. A locally running EBS, should be
comparable in speed to a raw local disk, perhaps a bit slower for yet
another layer of abstraction. If EBS lives remotely, perhaps in a
completely idle EC2 cloud, a remote EBS might perform better than a
local disk (assuming network communication is lighter-weight than
SATA/PATA bus operations), but I can't imagine how this can hold true in
a large scale and loaded cloud scenario, where shared infrastrucutre
(network, S3, etc) can become congested under load.
I don't see how EBS can be faster than local disk. Can you elaborate
more on this claim?
</pre>
</blockquote>
<pre wrap="">They state that it is purely network based (they do not list the technologies
they use but this could be infiniband, iscsi, etc.). It's not uncommon to see
a SAN etc. faster than a local disk...
I made my statements based on Amazon documentation:
"The latency and throughput of Amazon EBS volumes is designed to be
significantly better than the Amazon EC2 instance stores in nearly all
cases."
I just googled and found this person showing that EBS wins on medium and high
powered instances (although someone comments at the end that 'dd' tests are
not the best thing to measure why EBS is better):
<a class="moz-txt-link-freetext" href="http://developer.amazonwebservices.com/connect/message.jspa?messageID=125197">http://developer.amazonwebservices.com/connect/message.jspa?messageID=125197</a>
</pre>
</blockquote>
<pre wrap=""><!---->
Also, as I was saying, using RAID can make it even better, found some number
for that:
<a class="moz-txt-link-freetext" href="http://af-design.com/blog/2009/02/27/amazon-ec2-disk-performance/">http://af-design.com/blog/2009/02/27/amazon-ec2-disk-performance/</a>
Tim
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
===================================================
Ioan Raicu, Ph.D.
===================================================
Distributed Systems Laboratory
Computer Science Department
University of Chicago
1100 E. 58th Street, Ryerson Hall
Chicago, IL 60637
===================================================
Email: <a class="moz-txt-link-abbreviated" href="mailto:iraicu@cs.uchicago.edu">iraicu@cs.uchicago.edu</a>
Web: <a class="moz-txt-link-freetext" href="http://www.cs.uchicago.edu/~iraicu">http://www.cs.uchicago.edu/~iraicu</a>
<a class="moz-txt-link-freetext" href="http://dev.globus.org/wiki/Incubator/Falkon">http://dev.globus.org/wiki/Incubator/Falkon</a>
<a class="moz-txt-link-freetext" href="http://dsl-wiki.cs.uchicago.edu/index.php/Main_Page">http://dsl-wiki.cs.uchicago.edu/index.php/Main_Page</a>
===================================================
===================================================
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