Can I set up a replica set in MongoDB 1.8 using servers with different amounts of RAM?
- server1: 5gb
- server2: 2gb
- server3: 4gb
If yes, what are the pros and cons?
Can I set up a replica set in MongoDB 1.8 using servers with different
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Can I set up a replica set in MongoDB 1.8 using servers with different amounts of RAM?
If yes, what are the pros and cons?
No, you do not need equal RAM. (Yes, you could set up a replica set as described.)
MongoDB uses memory-mapped files for all caching, which means that cache paging is handled by the operating system. The replicas with more memory will keep more of the database in memory; those with less will page more to disk.
MongoDB will eventually bring the entire database into memory if it can. If you’re using two replicas for reads and one for writes, you might want to use the 5gb and 4gb machines for reads, so they are more likely to be hitting RAM.