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Category: Administration

sp_BlitzInMemoryOLTP

Published 2018-06-04 by Kevin Feasel

Ned Otter announces a new tool for troubleshooting memory-optimized databases:

Instance level evaluates the following:

  • the version/edition of SQL server

  • SQL Server ‘max memory’ setting

  • memory clerks

  • XTP memory consumers, aggregated

  • XTP memory consumers, detailed

  • the value of the committed_target_kb column from sys.dm_os_sys_info

  • whether or not instance-level collection of execution statistics has been enabled for all natively compiled stored procedures (because this can kill their performance….)

  • when running Enterprise, if there are any resource groups defined, and which memory-optimized databases are bound to them

  • XTP and buffer pool memory allocations, because In-Memory OLTP can affect on-disk workloads

  • summary of memory used by XTP

There’s a lot of useful information you can get out of this procedure.  Click through for the full documentation.

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Dumping Error Log Data Into A Table

Published 2018-06-04 by Kevin Feasel

Kenneth Fisher has a script to take information out of the error log and put it into a table:

This is one of my favorite scripts. It pulls all of the data from the error log and dumps it into a temp table. I did one version here but it was pretty specific to I/O errors. I also gave some homework to find/build a script like it. So if you didn’t do the homework here is a nice little (more generic) script that I personally find extraordinarily handy. There are two parameters at the top that will restrict the data pulled in, and a query against #LogInfo at the bottom that filters out backupand logon entries since they tend to get in the way of what I’m looking for. That said, if you want to create a report on logons (or backups) you’ll want to modify the query. I do leave #LogInfo open and the end so you can run multiple queries against it.

Click through for the script.

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Tell Me When tempdb Is Low On Space

Published 2018-06-01 by Kevin Feasel

Dave Mason shows how to configure alerts to fire when tempdb is low on disk space:

Naturally, the job runs on a predefined schedule. But how frequently should we check disk/available space for [tempdb]? The temporary nature of [tempdb] makes this a difficult question: objects within aren’t saved from one session of SQL Server to another, and evidence to explain runaway growth or loss of available space may be gone before an assessment can be made. Whatever schedule I decide on, I’ll always wonder if it’s frequent enough (or too frequent).

It’s tempting to “over-schedule” a job’s frequency, perhaps as much as every X seconds. Asking SQL Server “Are we out of disk space?” over and over again doesn’t make a lot of sense to me, though. It reminds me of Bart and Lisa asking Homer “Are we there yet?”until he snaps. Ideally, instead of asking, I want SQL Server to *tell me* when disk/available space is running low.

Read on to see how Dave does this.

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Does Your Server Have Too Much Memory?

Published 2018-05-30 by Kevin Feasel

Brent Ozar has a few tips to see if you have too much memory:

Sounds impossible, right? The saying goes that you can never be too rich or too thin or have too much memory.

However, there is one good indication that your SQL Server is probably overprovisioned, and to explain it, I need to cover 3 metrics.

1. Max Server Memory is set at the instance level: right-click on your SQL Server name in SSMS, click Properties, Memory, and it’s “Maximum server memory.” This is how much memory you’re willing to let the engine use. (The rocket surgeons in the audience are desperate for the chance to raise their hands to point out different things that are or aren’t included in max memory – hold that thought. That’s a different blog post.)

If you have too much memory, I’d happily borrow a cup of RAM.

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VLFs: How Many Are Too Many?

Published 2018-05-24 by Kevin Feasel

Randolph West looks at a baseline for the maximum number of Virtual Log Files for a database:

In a transaction log with too many or too few VLFs we might experience performance issues under a normal workload, as well as during the backup and restore process.

So what is the “right” amount? In customer engagements, I follow a guideline proposed by Glenn Berry of SQLskills.com in his Diagnostic Information Queries, to keep the number of VLFs at or below 200. In my opinion, any number higher than that is cause for concern.

On the other hand, Brent Ozar Unlimited has a popular script called sp_Blitz which proposes a maximum VLF count of 1000. To Brent, a number higher than that is cause for concern.

I tend toward the lower number, but if you have a smoothly-functioning environment and some databases have 700 or 900 VLFs, I probably wouldn’t give it a second thought.

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dbachecks Improvements

Published 2018-05-22 by Kevin Feasel

Rob Sewell shows off some improvements in the dbachecks library:

With the latest release of dbachecks we have added a new check for testing that foreign keys and constraints are trusted thanks to Cláudio Silva b | t

To get the latest release you will need to run

You should do this regularly as we release new improvements frequently.

We have also added better descriptions for the checks which was suggested by the same person who inspired the previous improvement I blogged about here

Click through for more details.

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Installing OpenSSH Server: Windows 10 Edition

Published 2018-05-18 by Kevin Feasel

Anthony Nocentino shows us how to install OpenSSH server on Windows 10 update 1803:

So in yesterday’s post we learned that the OpenSSH client is included with the Windows 10, Update 1803!  Guess, what else is included in this server, an OpenSSH Server! Yes, that’s right…you can now run an OpenSSH server on your Windows 10 system and get a remote terminal! So in this post, let’s check out what we need to do to get OpenSSH Server up and running.

First, we’ll need to ensure we update the system to Windows 10, Update 1803. Do that using your normal update mechanisms.

With that installed, let’s check out the new Windows Capabilities (Features) available in this Update, we can use PowerShell to search through them.

Anthony goes through the steps for configuration, so check that out.

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Updating A Table Using Change Data Capture Without Downtime

Published 2018-05-18 by Kevin Feasel

Robert Blackburn takes us through the steps of updating a table which uses Change Data Capture without taking a downtime window:

Steps

  1. Stop jobs that process CDC (SSIS).

  2. Inside a transaction with isolation level serializable: Alter Table schema and create temporary CDC table

  3. Copy old CDC rows to new table excluding dup rows (based on [__$seqval])

  4. Disable old (original) CDC table (schema is outdated). Will drop table

Click through for the rest of the steps and an example script.

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RDP Error: CredSSP Encryption Oracle Remediation

Published 2018-05-17 by Kevin Feasel

Kerry Tyler explains an error message popping up in RDP sessions:

In March, a vulnerability in CredSSP (Credential Security Support Provider) was patched, which would affect authentication via RDP (this is outlined in advisory CVE-2018-0886).  However, it was implemented in such a way that the behavior change didn’t have to be “honored” by either the server or the client involved in an RDP session.

The intent was that this would be controlled by GPO in enterprise environments, and a new GPO setting to activate or deactivate this behavior was released at the same time.

GPO settings have a default value, which they will use when nothing has been explicitly set for a particular setting. In this case, the GPO has three possible values: Force Updated Clients (for servers to only take connections from patched clients), Mitigated (for both, and on a workstation means that it won’t fall back to old/insecure behavior when attaching to unpatched servers), and Vulnerable (for both, and means what it sounds like–anything goes!).

In March, the default behavior was set to “Vulnerable”, which means everything kept working for everyone. But in the May security rollup, the default setting for that GPO was flipped to “Mitigated” if there was not an explicit setting for it…

If you get this error, the best thing is to patch the machines involved, but Kerry shows the workaround you can use if you need to use RDP in the meantime to connect to an unpatched machine.

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OpenSSH Now Built Into Windows

Published 2018-05-17 by Kevin Feasel

Anthony Nocentino is excited about the latest release of Windows 10:

Today is a big day! The OpenSSH client version 7.6p1 is now part of the Windows 10 operating system! Microsoft released Windows 10 Update 1803 and included in that release is the OpenSSH client, which is installed as part of the update.

That’s right an SSH client as part of the Windows operating system by default! Also included with this update is the OpenSSH Server which is included as an Windows Feature on Demand.

Let’s take a look at what this is all made of!

I’m still going to use PuTTY for my SSH needs, but it’s nice to see that there’s a default option if you’re in a pinch and working on an unfamiliar server.

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