[DOCS-12952] Investigate changes in SERVER-11328: 4.4 only Allow concurrent draining shards Created: 13/Aug/19  Updated: 29/Oct/23  Due: 20/Mar/20  Resolved: 17/Mar/20

Status: Closed
Project: Documentation
Component/s: None
Affects Version/s: None
Fix Version/s: 4.3.1, 4.2.1

Type: Task Priority: Major - P3
Reporter: Backlog - Core Eng Program Management Team Assignee: Kay Kim (Inactive)
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
Documented
documents SERVER-11328 Allow concurrent draining shards Closed
Participants:
Days since reply: 3 years, 47 weeks, 1 day ago
Epic Link: DOCS: 4.4 Server Release Work

 Description   

Description

Downstream Change Summary

4.4 ONLY::: Update the sharding documentation where it says that only one shard can be in the removing state.

Description of Linked Ticket

Currently only one shard can be removed at a time. I trust that this was changed for a good reason but I feel a distinction should be made between actively draining a shard (which was problematic to do for more than one shard at the same time apparently) and tagging a shard as draining.

The reason being is currently if we want to remove 5 shards for example and when the first of those 5 shards is draining it will potentially move its chunks to one of the other 4 shards that we want to remove anyway. This makes our cluster down scales unnecessarily slow since it's needlessly moving the same chunks around multiple times.

The proposed solution is as follows :

  • Allow marking multiple shards as "draining"
  • Balancer picks one of these draining shards as the one that is going to be drained completely
  • Balancer avoids moving chunks to shards that are marked as "draining"

Scope of changes

Impact to Other Docs

MVP (Work and Date)

Resources (Scope or Design Docs, Invision, etc.)



 Comments   
Comment by Kay Kim (Inactive) [ 17/Mar/20 ]

For 4.4 only.

Comment by Githook User [ 17/Mar/20 ]

Author:

{'email': 'kay.kim@10gen.com', 'name': 'Kay Kim', 'username': 'kay-kim'}

Message: DOCS-12952: concurrent draining shards
Branch: master
https://github.com/mongodb/docs/commit/6dc5e77a3f7c1b6dfb72386a5a59f5baa98bf9ee

Comment by Kay Kim (Inactive) [ 17/Mar/20 ]

Great. Thanks!

Comment by Melissa Plunkett [ 17/Mar/20 ]

kay.kim my understanding is 4.4 only. This will time nicely with it being exposed after cloud can support (which is in code review now). Thank you!

Comment by Kay Kim (Inactive) [ 04/Dec/19 ]

Will put this blocked until ready to work on for 4.4

Comment by Melissa Plunkett [ 17/Oct/19 ]

FYI on timing - Automation will do in Q4, Atlas will likely add that in Q1 so we are looking at 4.4 for release and hence documenting this.

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