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From Mark Ramm <>
Subject Re: Live testing of SF download mirrors
Date Wed, 18 Apr 2012 17:35:37 GMT
Hi Joost,

> the download numbers are impressive and they reflect mostly the activity we
> had between releases. Directly after a release the numbers will have peak
> values. I'm not sure if's load balancers will be able to handle this
> kind of load alone. MirrorBrain was quite stable and the service had to be
> restarted occasionally.

Thanks for bringing up some good technical questions. I definitely
respect what MirrorBrain has done for the OO project, and think we
should all work together to best serve the AOO users.

Let me start out by saying that we have ops support 24/7, contracts
with partners and all the human resources needed to fully support the
AOO  release and manage any issues that might come up.

On the load side I am confident that our mirror redirectors will
handle an order of magnitude higher than current total load (more than
5 million downloads/day). And most of that load is not AOO related,
and is very stable and predictable.  We have had no trouble handling
peaks from VLC and other projects that get millions of downloads per
month with the current hardware.

Additionally the redirectors and associated load balancers are
horizontally scalable, and should greater capacity be needed we can
quickly deploy more virtual servers to increase capacity.

So, I don't believe there is any reason to be concerned about risk at
the mirror redirector level, and we should not see any need for
restarts, or any instability there.

> How many mirrors does use ?

I don't believe there is any reason to be concerned at the individual
mirror provider level either.

We have 30+ mirror partners -- but many of those are organizations
with multiple delivery points. For example, one "mirror" provider has
more than 20 global delivery points, and enough bandwidth committed to
us to handle 8x current AOO download traffic.

> Does it provide a bandwidth comparable to the current OOo mirror network
> (AFAIR it was 2.5 TBit/s) ? For more information about the mirrors see

Total mirror network bandwidth is an elusive number, and somewhat
besides the point; because other factors like the number of concurrent
connections per mirror can quickly become the choke point for a
smaller mirror provider.  And of course individual mirror bandwidth
can create a local choke point even while there is plenty of available
"global" bandwidth.Which is why we needed a test to get more detailed
insight into the traffic patterns. Given that test is complete we are
now sure that we have a strong enough global network of well
provisioned mirrors with more available bandwidth, more concurrent
connection capacity, and more resources in general than we believe the
AOO release could possibly consume.

With that said, because we don't know the exact burst levels, and we
want to be ready for anything, we have also engaged a partnership with
a large global CDN provider to give us enough additional burst
capacity to handle severa terabits per second on the CDN alone.

So, the combination of the existing mirror network and the ability to
handle burst loads using additional CDN services puts us in very solid
shape to be able to handle a whatever traffic gets sent our way.

Because we are deploying some resources are which are expensive, we
have just asked that we be notified in advance of any changes to plan,
so that we don't end up incurring costs that aren't necessary create
value for the open source community and our users.

But, our main goal is to always to help open source projects be
successful. And in this case we want to help the AOO team to serve
their users, and to have the freedom not to have to worry about
bandwidth, concurrent connections, or any of the other details of
providing reliable download infrastructure, and to focus on promoting
this release and growing the AOO user and developer communities.

--Mark Ramm
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