Voice of the DBA

Tag: administration

Using the DAC with SSMS
I’m writing this post as a way to help motivate the #SQLNewBloggers out there. Read the bottom for a few notes on structuring a post.

While troubleshooting another issue, I needed to connect to SQL Server with the DAC. I couldn’t remember the syntax, so I looked it up quickly and ran into this link: Diagnostic Connection for Database Administrators. I added the ADMIN: to my connection in SSMS for a query window and clicked Connect.

This took entirely too long and then I got this:

That error resulted in a rabbit trail for me to debug this, but it worked out and I’ve learned a few things. The main one is to be sure that I’ve read the documentation and errors correctly.

As I tried a few things, including SQLCMD, I realized I had issues. I searched and found that the DAC gets set to a specific port. I checked the error log to get the number.

With that, I added it to my connection dialog, sure that this would work, but of course, it didn’t.

Eventually I stumbled on the post about errors and realized I should have checked the SQL Browser earlier. I thought about it, but discarded that thought because I could connect in other ways. Mistake. Check networking first, and networking is where the browser comes in. Sure enough, it was stopped.

The properties were set to DISABLED, so I had to change that before I could start it. I assume you can do that, if not, poke around the properties until you find that setting. With that changed, I started the service.

Then I could connect. Here’s the SQLCMD version.

With this working, the first command dialog at the top of this piece worked from an SSMS query window.

SQLNewBlogger

This was longer. What I thought was a quick lookup turned into a troubleshooting exercise that lasted about 20 minutes as I searched, read, experimented, etc. At least I made a bunch of screenshots as I was experimenting, so I had lots of data and didn’t duplicate anything.

The actual writing was only about 10 minutes, most of that looking through screenshots and trying to organize my thoughts.

References
- Enabling the DAC – http://www.mssqltips.com/sqlservertip/1801/enable-sql-server-2008-dedicated-administrator-connection/
- The DAC: Why, When, How – http://www.brentozar.com/archive/2011/08/dedicated-admin-connection-why-want-when-need-how-tell-whos-using/
- Errors when Trying to Use DAC Connection in SQL Server – http://www.sqldbpros.com/2013/10/error-when-trying-to-use-dac-connection-in-sql-server/
June 11, 2015
T-SQL Tuesday #67 – Extended Events for DBCC

It’s the second Tuesday of the month and time for another T-SQL Tuesday. This time it’s #67 from Jes Borland on Extended Events. You can read the invite, and whether you can participate today or not, write your blog and leave a comment for Jes on her blog.

If you want to see all the topics from the past, I have them on a post here.

If you want to host, contact the founder of T-SQL Tuesday, Adam Machanic. He chooses the hosts and is always looking for people that want to participate. You just need a blog and a good idea.

Who Ran DBCC?

I ran across a question recently from someone that said DBCC messages had appeared in the error log, but no one had run DBCC. That’s not possible as DBCC isn’t run without someone, whether that’s a human or a service, executing the DBCC command.

In the past, I might recommend a trace to track this, but not I’d choose an Extended Events (XE) session. I’ll show how to set up a simple session, though be aware I’m not an XE guru. I’m sure there are better ways to structure this, but it worked well for me.

You can start quickly building a specific XE session by right clicking the Sessions folder under Extended Events in SSMS under Management. I tend to pick the wizard for getting started, though be sure to save the script later.

From here we get the opening screen for XE, which I won’t show. The next screen asks for a name for the session. It doesn’t matter, but once you start using XE, you’ll start to get quite a few session, so it’s handy to pick something that’s simple and easy to understand later.

I can choose to start the session here when I’m done, but don’t worry if you’re not sure. You’ll get a chance again later.

The next step is to decide whether you use a template or build a session from scratch. I’m not sure if any of these templates will work well as I haven’t dug in. In my case, I decided to just choose a generic session.

Now I need to pick the events. There are a lot, but I went down to get the sql_statement_completed as my event. This will let me see the text of a call, which is what I need.

A couple notes here. One, you might want to grow this screen so that you can read what’s in the lower windows. I know there’s a lot of data here, but this screen doesn’t seem well defined.

The second note is that don’t forget to add the event with the arrow button. Until you have an event (or multiple events) in the right window, you can’t click "Next".

The next step is to get the data fields you need. Again, there are a lot, and I limited this to what I needed. I grabbed the client host and app, as well as the database. Then I grabbed the service_principal_name and sql_text as well. This should let me determine who’s running the command.

I’ve got lots of data here, but I only care about the execution of dbcc checkdb. This means I need to filter things, which is my choice with the next screen.

Here I need to click in the top line to get a place to add a filter. Then I select sql_text from the drop down and choose like for the operator and "dbcc checkdb" for the value. This should grab events that execute with a dbcc call.

I have to choose where to store this data. Since this is mostly a check for me, I can just use the ring buffer and keep data in memory. I lowered this to 10 events, but you can certainly pick what works for you. If you care about auditing, drop this in a file. For a small session like this, there’s not much data that’s going to be captured.

I get a summary screen, which lets me review settings. I haven’t shown it here, but once I pass that, I get the "Success" screen. This is where I can start the session, and actually watch live data if I want.

For this, I’ll watch the live data.

I decided to test this first and see if it captures anything else. I ran a few queries, and then this:

Still a blank, live data screen. Then I ran checkdb. I saw the results, and then ran it a few more times.

As you can see, I now can see that I ran checkdb against the EncryptionPrimer database.

This lets me do some quick auditing of what’s happening with my DBCCs. A smart DBA might even use this to ensure that DBCC is being run against some databases, perhaps on a spare machine.

June 9, 2015
DB_Owner Querying for Database Options

Another post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQLNewBloggers.

What can a user with the db_owner database role do? I assumed anything inside of the database (create/alter objects, assign permissions, back up the database, etc). However someone asked recently about whether someone could read database properties. I’d assume they can, but I needed to check.

I decided to start by creating a new login. I have lots on my test instance, but I went with just building a new one. I used the GUI to add [DBOwnerTest] because it’s quicker. I assigned a password, set a default database, and mapped this user to db_owner in a database.

I then opened a query window and changed the connection:

Now I could easily run a query for properties and see the results:

Note the connection at the bottom of the image above.

Here’s where it’s a little interesting. I disconnected Object Explorer and connected back as DBOwnerTest. I see this:

Looks normal. According to the BOL documentation for permissions, db_owner gets View Any Database as well as control over their own database. I can see the properties of the Sandbox database (where I’m db_owner).

But I can’t see properties of other databases.

I also see my login, but not the couple dozen others I have, other than sa. That’s curious, and perhaps not good. However this isn’t the place to delve into that.

I have the ability to query through databasepropertyex(), which I’ve documented in another post.

Certainly db_owner conveys lots of rights to the user, and certainly the ability to see some of the outside of the database container, such as the options and properties, as well as other databases.

Writing

This was based on a question I saw posted at SQLServerCentral. It took me about 5 minutes to set up a test login and query for information. I had to perform a few searches and try some queries. I spent a few minutes researching databasepropertyex(), which became another post.

All told, this was about a 15 minute post.

You can do this. Join the #SQLNewBlogger group and start documenting your career. You can see all my posts that fall into this area by looking through the SQLNewBlogger tag here.

References

Permissions of Fixed Database Roles – https://technet.microsoft.com/en-us/library/ms189612%28v=sql.90%29.aspx

May 21, 2015
Naming Confusion

When I first worked in a corporation that had many servers, I had to learn the encoding of our systems. We had SUIS01, SUIS02, NAIS01, NAOP01, etc. Each name designated a location and department, but no information as to what applications were running. That was a separate thing to learn, which thankfully didn’t change often as procuring and setting up a new system was a relatively rare event.

However I also ran into a few systems named “Dorothy” and “Wiz”. The other administrators griped constantly about the unprofessionalism of those names. I’m not sure I think SUIS01 is better or worse than Dorothy, but that’s a separate debate. In both cases, we had to memorize what applications were actually running on which systems. Since all of them were managed by IS, regardless of the department that owned them, we were responsible for understanding the purpose of the server.

I ran into a situation recently where a company had a server called SalesSQL, which was there production server. The development server was SalesSQL_Dev, which is fine until you see someone opening SSMS, thinking they’ve connected to the right server since they see “SalesSQL” in the connection dialog and starting to execute code. Granted, even a rookie should be able to notice the “_Dev” (or a similar “Dev_SalesSQL” name), but mistakes happen.

I wonder sometimes if naming systems too closely to similar systems in different environments is a good or bad idea. I especially get concerned if shortcuts are taken with database names like “Sales” and “Salesqa”. I think it can be easy to confuse those systems when you become stressed or are in a hurry and are glancing at a small drop down box.

Ultimately I’m not sure there’s a good method for naming systems that prevents confusion, and ensures people are working in the correct environment. I have tended to use suffixes in my career to denote development and test environments as I can more easily differentiate a dev environment, but I wonder if I shouldn’t be using prefixes instead. Having to retype the beginning of a name (or delete the “dev”) in the connection dialogs might force me to do extra work to connect to a production system. That little extra bit of effort might be just the thing to reduce the chance of performing development work on a live system.

Steve Jones

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May 21, 2015