[DOCS-387] FAQ entry for shard balancer prioritizing of chunk migrations and draining Created: 09/Aug/12 Updated: 13/Nov/23 Resolved: 21/Feb/13 |
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| Status: | Closed |
| Project: | Documentation |
| Component/s: | manual |
| Affects Version/s: | None |
| Fix Version/s: | mongodb-2.2, Server_Docs_20231030, Server_Docs_20231106, Server_Docs_20231105, Server_Docs_20231113 |
| Type: | Improvement | Priority: | Blocker - P1 |
| Reporter: | Jeremy Mikola | Assignee: | Kay Kim (Inactive) |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Participants: | |||||
| Days since reply: | 10 years, 51 weeks, 6 days ago | ||||
| Description |
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Scenario: A sharded system has uneven chunk distribution. The user removes a shard (setting it to drain) and adds new shards. The balancer prioritizes moving chunks to reach equilibrium before draining the removed shard. This priority is not configurable. Two alternative solutions:
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| Comments |
| Comment by auto [ 21/Feb/13 ] |
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Author: {u'date': u'2013-02-21T19:54:24Z', u'name': u'Sam Kleinman', u'email': u'samk@10gen.com'}Message: merge: |
| Comment by auto [ 21/Feb/13 ] |
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Author: {u'date': u'2013-02-20T17:39:52Z', u'name': u'kay', u'email': u'kay.kim@10gen.com'}Message:
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| Comment by auto [ 21/Feb/13 ] |
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Author: {u'date': u'2013-02-20T17:39:52Z', u'name': u'kay', u'email': u'kay.kim@10gen.com'}Message:
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| Comment by auto [ 21/Feb/13 ] |
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Author: {u'date': u'2013-02-20T17:39:52Z', u'name': u'kay', u'email': u'kay.kim@10gen.com'}Message:
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| Comment by Scott Hernandez (Inactive) [ 12/Sep/12 ] |
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This is not true with 2.2+. The balancer will first remove chunks from the draining shard before general balancing: https://github.com/mongodb/mongo/blob/master/src/mongo/s/balancer_policy.cpp#L210 With pre-2.2 it will balance first, then move off the draining shard's chunks. |