I get so frustrated when trying to determine where to start when a user comes to me and tells me that "the database is slow". Launching Performance Monitor and. Understanding and resolving SQL Server blocking problems. Blocking is an unavoidable characteristic of any relational database management system (RDBMS) with lock.

CPU Ready Time in VMware and How to Interpret its Real Meaning(If you’re having persistent problems with your virtual machine configurations and SQL Server performance, Jonathan can help you fix it – fast! Click here for details.)In the last month I have had to explain how to interpret CPU Ready Time information for SQL Server VMs running on VMware to a number of people. The first time was on Twitter, and the topic is really too big for a 1.

Most DBAs hoard their own favourite T-SQL scripts to help them with their work, often on a USB 'thumbdrive', but it is rare that one of them offers us a glimpse of. 6 Proven Steps to the Best Out of Search in SharePoint 2013. Windows Azure and SQL Azure Can’tfine. MS-Unified Cunications\#1601. The #1 SQL Server community and education site, with articles, news, forums, scripts and FAQs. Please confirm that you want to add 70-461 Session 1: Querying Microsoft SQL Server '12-16 T-SQL to your Wishlist. Add to Wishlist. This SQL Server video training with Garth Schulte covers Microsoft’s in-demand server and includes topics such as creating and altering tables with T-SQL. In my previous blog post, I had shared how you can leverage SQL Server Performance Dashboard SSRS Reports for monitoring and point in time troubleshooting for large. Is there a way to list the queries that are currently running on MS SQL Server (either through the Enterprise Manager or SQL) and/or who's connected? I think I've got.

I went ahead and gave it a shot. It is rare in my experience for SQL professionals to know anything about virtualization under VMware or Hyper- V, which is why we spend a half a day, or more, on virtualization during IE3: High Availability & Disaster Recovery. Based on my experience, I was surprised to see the question being asked on #sqlhelp at all. It turns out that Idera Diagnostics Manager has been updated to include information about VM performance that is collected from the Virtual Center if you have it installed in your data center.

Now, overall this is a good thing because DBAs now have additional information that they didn’t have access to unless they had negotiated access to Virtual Center with their VM Administrator. My experience consulting is that few DBAs have access to, or even know about Virtual Center, even though it is one of the critical tools for troubleshooting performance problems. Another item that most DBAs don’t know is that their VM administrator can configure roles and read- only security access to allow anyone the ability to see performance and configuration information inside of Virtual Center, but not be able to make changes, so there really is no good reason for a DBA to not have access to the performance data available in Virtual Center. Now that DBAs have access to the data, it is important to know what is being displayed and what it really means. Unfortunately, the way the information is being presented makes it easy to misinterpret what is being shown, so the end result is confusion for DBAs that don’t know a lot about VMware, or what the information they are looking at actually means. An example of the VM CPU Ready information from Diagnostics Manager is shown in the chart in Figure 1. Figure 1 – VM CPU Ready graph.

Looking at this chart on the report what would your first interpretation of it be? So far, 3 out of 3 people, including the one on twitter, have thought that there was a problem with this VM. The reality of the situation is that there is absolutely nothing wrong with this VM, it is doing just fine. It just so happens that the scale of this graph makes it easy to jump to an interpretation that this is showing a percentage value, and we all know that anything performance related that is over 8. It doesn’t say that, but it doesn’t provide any context for the information’s meaning either.

To make matters even more confusing, CPU Ready in VMware is available as a summation value, which happens to be what is shown here in milliseconds, and as a percentage (RDY% in esxtop) of time spent waiting with work to do to be scheduled by the hypervisor. We can confirm that the information presented is the summation value and not the percentage by looking at the real- time information available in Virtual Center for the same server as shown in the chart in Figure 2. Figure 2 – CPU Ready real- time summation from Virtual Center.

So now that we know it’s a summation and represented in milliseconds what exactly does that tell us? Unfortunately, it actually doesn’t tell us anything on it’s own.

What is CPU Ready Time and why do we even care? CPU Ready Time is the time that the VM waits in a ready- to- run state (meaning it has work to do) to be scheduled on one or more of the physical CPUs by the hypervisor.

It is generally normal for VMs to have small values for CPU Ready Time accumulating even if the hypervisor is not over subscribed or under heavy activity, it’s just the nature of shared scheduling in virtualization. For SMP VMs with multiple v. CPUs the amount of ready time will generally be higher than for VMs with fewer v. Download Photo Morphing Software For Mobile. CPUs since it requires more resources to schedule/co- schedule the VM when necessary and each of the v. CPUs accumulates the time separately. At what point does CPU Ready Time start to affect performance?

To be honest it is always having some minimal effect, but it really depends on a lot of different factors, for example which CPU Ready value you are looking at and where you are getting the information. If you are looking at raw RDY% values from esxtop, the value has a completely different meaning than the summation values that are available from Virtual Center.

Inside of Virtual Center, the level of summation you are looking at when reading the values also affects the meaning that the value has, and you have to perform calculations to convert the summation into a percentage to know the effect as documented in the VMware Knowledge Base. In this case, for a real- time summation, the data point is actually a 2. At one point VMware had a recommendation that anything over 5% ready time per v. CPU was something to monitor. In my experience for a SMP SQL VM, anything over 5% per v.

CPU is typically a warning level and anything over 1. CPU is critical. The reason this specifically says per v. CPU is that each v. CPU allocates 1. 00% to the VM’s scheduling total, so a 4 v. CPU VM would have a scheduling total of 4. A 1. 0% CPU Ready on a 4 v.

CPU VM only equates to 2. CPU. If this isn’t already complex, it gets worse. This makes providing a general recommendation impossible for this counter, because it depends on a lot of different factors. For example, if the VM has had a CPU Limit placed on it, whenever the VM exceeds its allocated limit it will accumulate CPU Ready time while it waits to be allowed to execute again. If the CPU Limit is being enforced under business SLAs or a chargeback system, the VM could easily have high CPU Ready values that fit what is required for the configuration. Using the formula from the KB article to convert a summation value to percent, if we round the average of 8.

CPU ready. Four tenths of a percent CPU Ready time, which is not going to negatively impact the performance of the VM. The example VM shown above, also has 8 v. CPUs allocated to it, so after taking this into account, it really only has 0. CPU, well below the older recommended value. What scenarios cause high CPU Ready times?

While there are a number of scenarios where high CPU Ready times can occur, there are generally two common scenarios that I see when I am consulting. The most common reason tends to be host over subscription, where too many v. CPUs have been allocated per p.

CPU ratio wise. While ESX 5 supports a maximum of 2. CPUs per physical CPU, this is definitely a case where just because you can, doesn’t mean it’s good to do. As always your mileage may vary based on your specific VM workloads, but typically I start to see problems when a host is in the range of 2- 2. X over subscribed for server workloads. The second common scenario that I see where CPU Ready times are high is when a larger SMP VM for SQL Server, for example one with 4- 8 v.

CPUs is running on a host that has a lot of smaller VMs with 1- 2 v. CPUs for application servers. Depending on the number of physical processors, and the total number of v. CPUs allocated on the host, the larger resource allocation for the SQL Server VM results in it having to wait longer for the hypervisor to preempt the necessary physical CPUs to schedule/co- schedule the workload. Often in cases where this occurs, after asking some questions I find that the number of v.

CPUs for the SQL Server was increased from four to eight due to performance problems for the VM. Unfortunately, if CPU Ready time was the original problem, increasing the v. CPUs actually doesn’t improve performance, it generally makes things worse. What do I do if this is actually a problem?

SQL Server Faq . The primary design goal for DBCC CLONEDATABASE which the SQL Product team had in mind is to provide mechanism to create fast, minimally invasive and transaction ally consistent database clones, useful for query tuning. Database schema, statistics and query store are commonly required data for query tuning or troubleshooting sub optimal query plans and plan regressions. To make database cloning fast, minimally invasive and consistent, the copying of metadata objects is performed at the storage engine layer by taking a transient snapshot of the production database. Database cloning have proved to be significantly useful in reducing the troubleshooting time for dbas, developers and Microsoft CSS by extracting only the data required for troubleshooting from the production databases. In addition, cloning a database also help minimize the risk of providing access to production databases or sharing business data directly with developers or support teams. Although user tables & indexes data is not copied in the cloned database, user data is still available and exposed in cloned database via statistics and query store.

As the primary scenario for dbcc clonedatabase is troubleshooting, the default database clone contains the copy of schema, statistics and query store data from source database. Query store data is contained only in SQL Server 2.

ON in source database prior to running DBCC CLONEDATABASE. Note: To copy the latest runtime statistics as part of Query Store, you need to executesp. In this scenario, only copy of production database schema is desired in the database clone to compare it with that in dev environment. For some businesses, especially in healthcare, finance, data privacy is critical and no user data (including statistics and query store) can be shared with developers, vendors or support teams.

For this scenario, the following syntax introduced in SQL Server 2. SP1 can be used to allow users to create schema only database clones with no user data.— Creates Schema only database clone with no user data. DBCC CLONEDATABASE(source.

SSN or creditcard columns) which cannot be shared with anyone. Currently, DBCC CLONEDATABASE doesn’t support selectively including or excluding objects from the source database in the cloned database. If your requirement falls in this category, you can use any of the following techniques described below to protect data in cloned databases before it is shared with anyone.

Drop statistics on tables or columns containing sensitive business data in database clone. I have uploaded a TSQL stored procedure script in our Tiger Github repository which can be used to drop all the statistics from the specified table or column on the table. You can download and run the script against the cloned database. The stored procedure needs to be executed for each table or column containing sensitive data whose stats you would like to purge. The script purges the user as well as index statistics including indexes on primary constraints, however if there are any foreign key references, it should be dropped manually. If you would like to enhance or improvise the script, feel free to send a pull request on github for the benefit of SQL Community— Create a database clone with no query store. DBCC CLONEDATABASE(.

We recommend detaching the cloned database after the database is created. Column- level Encryption. If the columns in the source database is encrypted by using column level encryption, the statistics inside the source database are also encrypted which also ensures statistics copied in cloned database is encrypted.

The following script validates that behavior. USE . Thus, if the columns in the source database is encrypted using Always Encrypted encryption, DBCC CLONEDATABASE will exclude those objects present in the source database. Note: There is a known issue where if the source database contains always encrypted objects, running DBCC CLONEDATABASE against the database results into a AV causing the client session to terminate. We will be fixing the issue in upcoming CUs for SQL Server 2. The fix for the issue will avoid AV while creating database clone. Thus, the backup of the cloned database will be unencrypted. If it is desired to encrypt and protect cloned database backup, you can enable TDE on cloned database before it is backed up as shown below.

USEmaster; GOCREATEMASTERKEYENCRYPTIONBYPASSWORD=.