Why SQL Server Isn’t Responding – Symptoms, Causes & Solutions

Responsiveness is important for any SQL Server setup, as performance issues will harm any services that rely on your database to function as normal.

Troubleshooting an unresponsive instance is not always easy, and the first challenge is knowing where to look for issues.

Let’s delve into some of the common causes of performance snafus, the symptoms that they are associated with and the ways you can solve them.

Deadlocking

One problem might be a SQL Server deadlock, which occurs when two or more processes attempt to access resources that are being monopolized by exclusive locks imposed by other processes which are running concurrently.

Deadlocking is part and parcel of how SQL databases function, and is necessary to preserve the integrity of the information contained within the tables. However, deadlocks that occur frequently can compromise performance, so will need to be addressed.

You can diagnose deadlocking by looking at wait statistics, or by using a third party monitoring tool to identify and alert you to processes which were unable to complete because of a locking problem.

Depending on the type of deadlock, your troubleshooting tactics will vary, but generally, the solution will lie in tweaking orders of execution, or adjusting locking privileges for particular processes.

TempDB

SQL Server uses a temporary scratch database whenever a session is running, and this is known as TempDB.

In normal use, TempDB plays a vital role in keeping a database running smoothly. However, if data persists in it after the process which created it has completed, it can fill up over time. And if it hits its capacity, downtime might be on the cards.

Monitoring this to nip such issues in the bud sooner rather than later is sensible. You can also implement additional TempDB files, but this is only advisable if you don’t mind eating into more of your storage resources.

Rogue OS-level processes

SQL Server is prone to problems with OS-level processes, just like any standard desktop workstation or portable device. Sometimes processes can hog hardware resources unnecessarily, hampering responsiveness and spoiling the end-user experience.

If you see that performance is taking a hit and none of the aforementioned issues is the obvious culprit, then check to see if the OS is bogged down by a rogue process or two. Killing these could restore performance, and ideally, this will be a one-off complication that doesn’t recur.

Hardware

If you have checked that the software is not to blame when SQL Server responsiveness suffers, then the hardware could be the root cause.

How you tackle hardware problems will depend on the component in question. If your database’s memory capacity is being used up, then allocating more RAM in the settings will alleviate this temporarily, although an upgrade will eventually be needed.

If your storage resources are being squeezed, expansion is the only option, especially if you want your server to scale in the long term.

All of these issues, hardware or software, can be detected and dealt with if you monitor your SQL Server at all times, so SQL professionals must not shirk this responsibility.