Comment by Mario on "Better MongoDB Scalability Architecture ?"

CommentBetter MongoDB Scalability Architecture ?

Mario

Big Data Enthusiast

Dec 1, 2016

I would think that you would need to have at least 1 if not 2 replica sets to avoid being in the situation that you landed up in. Initially when we started off, even we thought .. hey we really don't need a replica set, since we are not going to have terabytes of data from day 1 of our business!!! But then RDBMS systems have their regular backup every week. If you have a replica set, you can consider it as good as a backup in case of a system or node failure. You are obviously going to have to pay for more space but its a good investment. Oh and do ensure that your replica set is in a different geographic area close-by.

Ahmed Ashraf

Dec 1, 2016

@mario_the_legend Thanks for reply .. but in the above structure photo .. the secondary (1,2) in each shard mean that there is a 2 replica sets in the same server run in deferent instances and ports .. but what confusing me is should I move replica set to another server in the same region or It will be okay if it was on the same shard ?

Ahmed, you can have a replica set for each shard. Since replication is asynchronous, it would happen on its own. To keep costs down you could perhaps have a single replica node per shard. If you have 3 shards, each of the shards will have 1 replica node attached to it, so you will have 3 replica nodes in total. You can have the replica's on the same region, its just that if there is an outage with that particular region's data centers, your replica would be as good as useless.

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