"How many SQL Server DBAs do we need?" - This is a question that often comes up in conversations with customers. Essentially, customers want to know if they have enough DBAs or too many. This is not a trivial question. If you do some research online via your favorite search engine, you will most likely come across numbers such as 40-65 DBs per DBA (for SQL Server). I remember finding another number relating to storage space instead of the number of DBs; the range was 3-5TB per DBA.
I have had custoemrs that had a team of 5-6 DBAs supporting a single application (logically a single DB). I have also had customers that had 2000-3000 DBs (not all prod, but still) per DBA. But just saying that a DBA can manage x number of DBs over y TBs of storage just doesn't seem right.
Here are the factors that I have found that influence the number of DBAs needed:
- Mission Criticality - If a DB is mission critical, it deserves more attention in order to stay available. The more it is intertwined with the success of the enterprise, the more DBA resources are needed.
- Churn - How often does data get loaded or get modified? Usually a DB that has minimal INSERTS/UPDATES/DELETES requires periodic attention for growth, index rebuilds, etc.
- Usage Patterns - Even a DB primarily used for Reporting with few updates can require attention if the usage of the DB changes. For example, a reporting DB that has many users that can query the data in anyway that they want can scream for attention.
- Permissions - But not in the secuity sense... Many DBs are from vendors which restrict what type of modifications that a DBA can perform such as restricting the additon of indexes for example.
- Skillset of the DBA Team - A team of DBAs that embrace standardization, atuomation, scripting (especially powershell) can manage resources more efficiently.
There are many other factors as well. I wish that I could say that I came up with a magical formula with these factors built in, but I have not. I never seem to run into those situations where there are too many SQL Server DBAs. With that iin mind, I have come across quite a few situations where a qualified DBA is needed either because there is none or the factors listed above warrant an addition of resources. How does this happen? SQL Server is "Simple". Just about anyone can install SQL Server and be up an drunning in no time. The default settings are adequate for many applications as they are initially built/installed. Over time, the usage of the system becomes greater and the importance of the data does as well. Before you know it, an organization may need a DBA and not know it.
If you are unsure that you need a full time DBA, consider a "DBA on-call" service or perhaps a local consultant who specializes in SQL Server. This type of service can also be helpful to support the organization if you have a DBA or a team of DBAs to cover for vacations, sickness, etc. The important thing to note is that you do not let your DBA be the potential single point of failure. When this happens, you truly understand the value of a well qualified DBA. Don't forget that DBAs are people too who have real lives. :-)