[SERVER-11328] Allow concurrent draining shards Created: 23/Oct/13 Updated: 19/May/20 Resolved: 13/Aug/19 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Sharding |
| Affects Version/s: | None |
| Fix Version/s: | 4.2.1, 4.3.1 |
| Type: | Improvement | Priority: | Major - P3 |
| Reporter: | Remon van Vliet | Assignee: | Kaloian Manassiev |
| Resolution: | Done | Votes: | 4 |
| Labels: | PM229 | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Environment: |
All |
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| Issue Links: |
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| Backwards Compatibility: | Fully Compatible | ||||||||||||||||||||||||||||||||||||||||
| Backport Requested: |
v4.2
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| Sprint: | Sharding 2019-08-12, Sharding 2019-08-26 | ||||||||||||||||||||||||||||||||||||||||
| Participants: | |||||||||||||||||||||||||||||||||||||||||
| Case: | (copied to CRM) | ||||||||||||||||||||||||||||||||||||||||
| Description |
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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 :
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| Comments |
| Comment by Sheeri Cabral (Inactive) [ 14/Jan/20 ] |
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Note that the actual solution allows more than one shard to drain at a time, so the actual solution is:
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| Comment by Githook User [ 16/Aug/19 ] |
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Author: {'name': 'Kaloian Manassiev', 'email': 'kaloian.manassiev@mongodb.com', 'username': 'kaloianm'}Message: (cherry picked from commit 52b0ba71843026f670b07a18f93d0db11b1c6852) |
| Comment by Githook User [ 12/Aug/19 ] |
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Author: {'name': 'Kaloian Manassiev', 'email': 'kaloian.manassiev@mongodb.com', 'username': 'kaloianm'}Message: |
| Comment by Remon van Vliet [ 23/Oct/13 ] |
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Was not aware of that. Good to know while we wait for this fix. Thanks! |
| Comment by Scott Hernandez (Inactive) [ 23/Oct/13 ] |
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Currently there is a workaround to keep the chunks from moving to those other shards until this feature is scheduled/done which is to set the shard maxSize to 1, or some really low number, which will keep the balancer from moving any chunks there (like during draining). |