Azure SQL managed Instance tiers comparison

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Azure SQL managed Instance tiers comparison

luiz.carvalho

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February 9, 2023 at 2:49 pm

#4147571

Hello everyone.
I have an azure general purpose managed instance, 8vCore, 1Tb storage running. The average CPU usage is 50%, with 70-75% in peak hours. Now we have a new report that need almost real-time data and since the server is heavy used, the query get a lot of concurrrency with writes tasks.
Noted that the business critical tier provides native high availability and reporting queries can be easily redirected to the free-of-charge secondary read-only replica. Also the BC tier provides a super-fast storage (local SSD) vs the actual remote storage. In that cenario I can separate read-write queries and read-only/analytic/reporting queries. At the end, it´s almost like getting twice the vCores and memory for the same price.
The question here resides in the comparison below:
Actual scenario:

Possible scenario:
Looking only for performance (do not consider the 500€ difference) should I make that change? In other works, less vCores, but faster storage subsystem and better hardware, should the 4 vCore BC tier performs better than a 8 vCore in general purpose tier? Considering that it´s 30% more expensive, I assume that the answer should be "yes", but would like to listen the experts opinions here.
Thanks a lot!
April 27, 2024 at 7:02 am

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Site Owners SSC Guru Points: 80325 More actions · Answer 1

Thanks for posting your issue and hopefully someone will answer soon.

This is an automated bump to increase visibility of your question.

ahazelwood SSC Rookie Points: 26 More actions · Answer 2

It really depends on your use case. For us, the extra memory and faster storage, helped us level out some of the performance issues we were having on the General Purpose tier, and allowed to go all in on Managed Instance. We are still using General Purpose for our test instance, but for production we switched to the Premium series - Business Critical.

Keep in mind several other benefits around the "free" read-only instance for your reporting needs.

Hope this helps a little.

luiz.carvalho SSC Veteran Points: 231 More actions · Answer 3

Thanks @ahazelwood. I know it really depends on the use case. My core point is: Considering both scenarios and using them at the maximum capacity allowed. If I move all que reporting queries to the read-only instance, would the 4vCore BC performes better than the 8vCore GP?

ahazelwood SSC Rookie Points: 26 More actions · Answer 4

From running both, it's going to come down to the size of your database. If it all fits in memory, then a slight increase with the faster cores, but if not, then the faster storage on the 4 core may be a huge benefit. If you can swing it, spin up a second instance and let me know your results.

Thanks.