Alexey Serbin has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/8133 )

Change subject: [tablet copy] end session before bootstrapping tablet
......................................................................


Patch Set 1:

> My understanding of it is the following. I would recommend that
 > would browse the code to make sure this is still the case.
 >
 > because by the time the tablet boopststraps the leader might have
 > ended up deleting all the logs that it needs to catch up to the
 > leader.
 > - say that you have wal segments 0-10 when tablet copy starts
 > - tablet copy will anchor 0 until its destroyed, meaning the source
 > wont delete it
 > - when tablet copy is done the tablet still needs to boostrap which
 > will take some time.
 > - when tablet bootstrap is done the replica will need to continue
 > catching up to the leader, this time through consensus. It needs
 > segment 11 to be still available.
 >
 > We need the anchor to still be alive at this point, otherwise
 > theres nothing preventing the leader from anchoring segment 11 and
 > thus making the new replica unable to catch up.
 >
 > True that we're not optimal, we're anchoring 0 and we might only
 > need to anchor 10/11 but no anchor at all is likely to cause
 > replicas to start to fail copying.

Thank you for the explanation -- I will need to dig into that to get better 
understanding of this.


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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I20592007a40113d8409f121b226bcccca14e8300
Gerrit-Change-Number: 8133
Gerrit-PatchSet: 1
Gerrit-Owner: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Alexey Serbin <[email protected]>
Gerrit-Reviewer: David Ribeiro Alves <[email protected]>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Mike Percy <[email protected]>
Gerrit-Comment-Date: Mon, 25 Sep 2017 20:50:47 +0000
Gerrit-HasComments: No

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