Alexey Serbin has posted comments on this change. ( http://gerrit.cloudera.org:8080/14783 )
Change subject: KUDU-3008 Spread replicas evenly with 2 locations and odd replica factors ...................................................................... Patch Set 1: (3 comments) http://gerrit.cloudera.org:8080/#/c/14783/1//COMMIT_MSG Commit Message: http://gerrit.cloudera.org:8080/#/c/14783/1//COMMIT_MSG@8 PS1, Line 8: Could you add some description here? The idea is to outline why 2 + 1 is better than 3 + 0, even if the location policy constraints are not held in neither case. I added an example of such a comment on placement_policy.cc file, maybe just add it in here? http://gerrit.cloudera.org:8080/#/c/14783/1/src/kudu/master/placement_policy-test.cc File src/kudu/master/placement_policy-test.cc: http://gerrit.cloudera.org:8080/#/c/14783/1/src/kudu/master/placement_policy-test.cc@858 PS1, Line 858: // Before this patch, all replicas will located at "B". nit: this comment doesn't have enough context if reading it as part of the code, not just part of this patch. Remove this or replace with the description of what's is going on here. Maybe: Make sure replicas are placed into both locations, even if ideal density distribution would have them in a single location. http://gerrit.cloudera.org:8080/#/c/14783/1/src/kudu/master/placement_policy.cc File src/kudu/master/placement_policy.cc: http://gerrit.cloudera.org:8080/#/c/14783/1/src/kudu/master/placement_policy.cc@337 PS1, Line 337: // is (3 + 3), while for 3 locations that's (2 + 2 + 2). Could you add a small note about distributing 3 replicas into 2 locations? The idea is to point to the benefits of that. Maybe, something like: In case of distributing 3 replicas among 2 locations, 1 + 2 is better than 3 + 0 because if all servers in the first location become unavailable, in the former case the tablet is still available, while in the latter it's not. Also, 1 + 2 is better than 0 + 3 because in case of catastrophic non-recoverable failure of the second location, no replica survives and all data is lost in the latter case, while in the former case there will be 1 replica and it may be used for manual data recovery. -- To view, visit http://gerrit.cloudera.org:8080/14783 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: If96361f6be686679dd72f08e28d964eae25875d0 Gerrit-Change-Number: 14783 Gerrit-PatchSet: 1 Gerrit-Owner: ZhangYao <[email protected]> Gerrit-Reviewer: Alexey Serbin <[email protected]> Gerrit-Reviewer: Kudu Jenkins (120) Gerrit-Comment-Date: Fri, 22 Nov 2019 20:03:56 +0000 Gerrit-HasComments: Yes
