[SERVER-3088] Combine Replica Sets and Shards to a single system, using RAID5 style parity Created: 12/May/11 Updated: 06/Dec/22 |
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| Status: | Open |
| Project: | Core Server |
| Component/s: | Replication |
| Affects Version/s: | None |
| Fix Version/s: | features we're not sure of |
| Type: | New Feature | Priority: | Major - P3 |
| Reporter: | Colin Davis | Assignee: | Backlog - Replication Team |
| Resolution: | Unresolved | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Assigned Teams: |
Replication
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| Participants: |
| Description |
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As discussed at http://groups.google.com/group/mongodb-user/browse_thread/thread/c18a9d181de2e5f6 , it would be tremendously useful for us to be able to use a RAID-5/6 style distributed parity system to combine ReplicaSets with Shards. The current system of sharding and using replica sets requires that we have 2x servers as we have shards. It would dramatically reduce the number of servers that large deployments need, if we could instead use RAID-5/6 style protection. While I'm sure you know how RAID works, it might be helpful to quickly review the exact mechanism- So in this system, with 5 shards, we'd use six servers. When any one of the systems went down, we could reconstruct it, by using the data remaining on the other 5. You can increase redundancy, by increasing the number of parity blocks. RAID6 uses the same system, but two parity blocks, to increase the overall reliability of the system, and ensure it can handle two If Mongo were to support such a system, companies could deploy dramatically fewer servers, while maintaining a very high level of reliability and failover. |
| Comments |
| Comment by Colin Davis [ 14/May/11 ] |
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I apologize for not understanding- Do you mean each Physical Hardware server would have one shard server, and two replica sets for shard servers on other machines? From my understanding of Mongo Sharding and replication, as described on the web and at http://bit.ly/dm6G9v If you had 5 Physical Hardware servers, you could run multiple Mongod instances on each server, giving you redundancy, but it would still require the same number of processes running in total, just spread across fewer machines, right? Do continue our RAID analogy, If I'm understanding you correctly, you seem to be suggesting partitioning the my drives, and then using RAID 0+1 to mirror partitions. I still need 2x-1 the server resources that I would with a RAID-5 style setup, no? I apologize again if I'm missing something. |
| Comment by Eliot Horowitz (Inactive) [ 14/May/11 ] |
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You can do this manually now. |