Doubts on replication strategy in CODA

[Sundaram, Arunkumar]

Hi Everyone,   First of all a big kudos to CODA community, it’s a wonderful job you guys are doing.   In one of the documents I read that CODA uses read-one, write-all approach for server replication. I am a little bit concerned here.   Let’s assume that there are three replicated servers A, B and C. And let’s assume that client Ac is connected to A, client Bc is connected to B and client Cc is connected to C.   In this scenario let’s say there is a file named “CommonFile” under root directory of CODA share. Consider a sequence of following operations on this file   Ac opens “CommonFile” for write Bc opens “CommonFile” for write Ac appends some content �A to “CommonFile” Bc appends some content �B to “CommonFile” Ac propagates �A to other replicated servers Bc propagates �B to other replicated servers lets say at this time �A is propagated to servers in the following order; first to A then to C and then to B lets say at the same time �B is propagated to servers in the following order; first to B then to C and then to A In this situation there is a chance for server A to have “CommonFile” + �B and lost �A server B to have “CommonFile” + �A and lost �B   Basically I would like to know whether there is any locking done when accessing a single file, if yes who is responsible for it. Or is it a limitation that files cannot be used simultaneously at two clients connected to two different duplicated servers.   Please feel free to clarify anything in this question with me; I may have not stated things clearly. Thanks in advance.   Cheers, Arun