You’re hosting your SQL Server databases in Amazon RDS, and performance has been getting slower over time. You’re not sure if it’s storage IOPs, instance size, SQL Server configuration, queries, or indexes. What’s the easiest way to find out?
Ask a few questions:
Are you using SQL Server Enterprise Edition? The smallest EE server, a db.r3.2xlarge, costs about $4,241 per month on demand (which isn’t the cheapest way to buy, of course). The next smallest doubles in cost, which means if the performance tuning efforts could drop you by just one single instance size, a consulting engagement would pay for itself well within two months.
Are you using mirroring for multi-AZ protection? If so, the delays required for sequential writes between availability zones may be your biggest bottleneck for inserts, updates, and deletes. Check your wait types with sp_BlitzFirst, and if the top ones are database mirroring, then the data changes aren’t likely to get faster with hardware tuning. Increased IOPs might help – but it takes deeper digging to get to that conclusion. It’s time to look at reducing your change rate in the database. If, on the other hand, your biggest bottleneck consists of select queries, consulting can help.
Are you locked into a long-reserved instance? You can sell reserved EC2 instances on the secondary market, but you can’t sell RDS instances as of this writing. If you’re having performance problems on it, this is definitely a time to call for consulting help fast. You want to avoid dumping the smaller instance and jumping into another commitment if a growing customer base or slowing code base could mean yet another instance type change.
Or are you running a single Standard Edition instance in just one AZ? Try standing up another RDS instance – but this time with the largest Standard Edition instance type you can get, around $12/hour as of this writing. Run the same types of queries against it, and within a couple hundred bucks of experimentation, you can get an idea of whether or not hardware will be a cheap enough solution. Granted – your time isn’t free – but it’s cheaper than a consulting engagement.
These questions help you figure out when it’s just cheaper to throw more virtual hardware at it.