production and qa databases on the same instance?

[dr...@yokee.tv]

Hi,

I'm considering to use our replica-set that holds a production database to hold also a look-alike QA database.

We're expecting to have very little traffic with the QA database, definitely negligible in comparison with the production so I am pretty sure it will hold ok as far as performance is related.

The alternative is to purchase 3 more servers for the QA and setup the database there.

The pros for multiple instances is that we'll need less maintenance and cost for servers.

The cons are that we're mixing QA and Production data on the same database, which is contrary to best practices. 

However, I am leaning towards the mixed setup.

What are the thoughts around that? 

What other issues I should consider?

Thanks in advance

Dror

[Kevin Adistambha]

Hi Dror,

It is generally not recommended to have production instances share resources with other processes. Off the top of my head, some of the challenges will be:

• Although the QA DB has little traffic, presumably it has the same amount of data as the production instances. This effectively cuts your disk space in half at the worst case.
• If anything goes wrong while being QA’d, production will be affected as well.
• There will be resource contention in the machines, resulting in lowering both QA and production throughput.
• You cannot perform any “stress-test” with the QA system, since it will be stressing the production system as well.
• Similarly, it is hard to QA new application patches if there’s a bug in the current application version that stresses the production system.
• Any issues with the production system (e.g. memory issues, performance issues) will be harder to trace since there are two database processes running at the same time.

Generally, the cons for mixing QA and Production servers in a single machine outweigh the pros.

Best regards,
Kevin

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