So I said, narrow the focus.
Your "use case" should be, there's a 22 year old college student
living in the dorms.
How will this software get him laid? - jwz
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Memcached hashing fun!
We use memcached extensively and have been upgrading from ubuntu hardy to lucid. We’re not quite a continuous integration house, but server farm upgrades are obviously done in tranches to measure and manage risk.
We just discovered that we bought this memcache change in the upgrade process. Resulting in our data in memcache being hashed differently on old servers to new servers. The impact, our databases would have erred towards doing the work twice as customers bounced between servers on each hashing format - no huge deal and didnt show up in our performance testing (the new boxes even came in faster!)
When the last live customer facing server swung over, we effectively stopped duplicating where we stored each piece of data, all data was now in newhash location and not oldhash location.
Of course - behind the scenes are the ‘odd’ servers that we haven’t upgraded yet still on the old library - none of these now had any access to the live data. A hilarious time was had by all tracking this down.
