On Wed, Aug 8, 2012 at 9:24 AM, vlad <[email protected]> wrote:
> Jeff, what storage subsystem did you use on your dedicated host? If you kept
> all data in RAM then it is just a sleuth of hand. Overall I am not surprised
> about lame performance of backends and pull queues. I am a bit surprised on
> the cost of doing it in Datastore. Good work!

Why do you call it sleuth of hand?  Storing the data in RAM represents
the actual business need.  We're doing not only an apples-to-apples
comparison but an "actual implementation of business case to actual
implementation of business case".

Persistent RAM is one of the principal values of a Backend, and it
turns out that they aren't very useful for that purpose.  Not only is
QPS low, but if you saw my post in Brandon's thread, latency is
erratic and horrible.

Just to give some latency numbers:  Urlfetches to the rackspace VPS
are consistently 30-50ms.  Not great, but tolerable.  Urlfetches to a
backend average about the same - they skew more towards 15-25ms, but
there are a large number of 250ms+ outliers that push up the
arithmetic mean.

No-op fetches F1 to B1:
https://img.skitch.com/20120808-nn749683wqdg5516fy732k71iw.jpg
No-op fetches F1 to B8:
https://img.skitch.com/20120808-gerejtgfd958i691hsiw897wjw.jpg

The test F1 to Rackspace:
https://img.skitch.com/20120808-npj3kutc2p511bw5gujxkm5kg4.jpg

BTW I picked Rackspace for this test because I happened to already
have a VPS there.  I would love to see latency numbers for Linode,
EC2, and Google Compute Engine.  Does anyone want to run the test?
I'm still waiting for an invite to GCE.

Jeff

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