[Openstack] time synchronization matters?

宋杰 nightelf1984 at gmail.com
Mon Dec 5 16:06:43 UTC 2011


Hi all,
   According to what I learned from swift source code, It seems that most
operations like object 'put' and 'replication' is highly depends on
timestamp.
   For example, when proxy receives an object 'put' request, it records the
timestamp which at last will be used by object server for  object naming.
During this process, the object server compares timestamp to check if there
is an older object existed, if so it will delete the older one. Now it
comes to my question: if multiple proxies are deployed, strict time
synchronization among them is really matters to make swift function well,
right? My thought is: when user uploads two same-path objects to two
separate proxies (say 1st upload -> p1; 2nd upload  -> p2), then if p2's
clock is far behind p1, the 2nd upload operation might effect nothing
though from the point of user's view it should be treated as final
version...
   If my understanding is correct, then what' your suggestions on deploying
multiple proxies in production environment?

-- 
life is a box of chocolate
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