Kenneth, 

Agreed that running on the master / slave datastore is a liability these 
days (which IMO is pretty irresponsible on GAEs part, I see no reason why 
major latency spikes can't be avoided even if there are advantages to the 
high replication datastore and we can eventually migrate. If we must 
migrate, give us a deadline, and fully support the master/slave until then. 
 but I digress...) but the DEEs we're talking about here are happening 
during warmup unrelated to datastore operations, and could effect anyone 
regardless of master/slave vs HR.  For these cases I think Brandon's advice 
is spot on: lower your max pending latency to 1s or so.

Usually when we get hit with DEEs related to being on master / slave, I can 
see a corresponding spike in the system status dashboard:

http://code.google.com/status/appengine/detail/datastore/2012/01/16#ae-trust-detail-datastore-get-latency

and at least I know what's going on.  Actually, despite my whining, the 
last time we were hit by DEEs related to master/slave datastore latency 
spikes was over a month ago - GAE folks if you are listening and you have 
been trying to improve the reliability of master / slave, thank you.  I 
think when we were getting pounded by DEEs last week I started to freak out 
and pointed the finger at master / slave latency prematurely when it was 
really related to DEEs during warmup.

Anyways, thanks to Brandon, I also know what's going on in the case of DEEs 
during warmup too!

Best,
Karl

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