Marek Maśko, Author at SQLTerritory.com

SQLDay2018 – Brief introduction into SQL Server Execution Plans

Last week I had a great pleasure to speak at SQLDay 2018. For those who don’t know – it is the biggest conference focused on databases, data platform, big data, advanced data analysis and business intelligence in Poland. It has been organized for 10 years already and is a great opportunity to meet many special people. This year it was a great chance to attend workshops and sessions delivered by real SQL Server experts: Itzik Ben-Gan (b|t), Kalen Delaney (b|t), and Niko Neugebauer (b|t), and many many more…

I had an amazing occasion to present my session titled Brief introduction into SQL Server Execution Plans.

Here you can find my slide deck and materials: SQLDay2018 – Brief introduction into SQL Server Execution Plans

I also posted it on my SlideShare profile.

-Marek

Share it:

24 HoP – SQL Operations Studio – slide deck

Last Thursday I had a great pleasure to present a session during 24 Hours of PASS Cross-Platform SQL Server Management. 24HOP is an exceptional online event that provides free training for database professionals. It’s 24 back-to-back hours webinar series that features a new 60-minute webinar each hour.

I had an amazing occasion to present my session about SQL Operations Studio – a New Multi-Platform tool for SQL Server Database Development, Administration, and Monitoring.

Here you can find my slide deck: SQLOps

I also posted it on my SlideShare profile.

-Marek

Share it:

A list of the software I use

Two weeks ago I was blogging about The Essential SQL Server Toolkit in my stack. That reminds me of an idea I had in January to post a list of software I usually use. At that time I was forced to create such list for myself because I was changing my laptop to the new one. I decided to post it here, so next time when I will have to reinstall my laptop I will have everything already in one place. Additionally, maybe you will find something interesting here as well.

Basic

Microsoft Office – Word, Excel, Outlook, Powerpoint, OneNote. (link)
Chrome – Web browser. (link)

SQLServer

Microsoft SQL Server – I think this doesn’t require any explanation. (link)
Microsoft SQL Server Management Studio – Data Management Tool. (link)
Microsoft SQL Operations Studio – Data Management Tool. (link)
Microsoft SQL Server Data Tools – SQL Server Tools for developers. (link)
RML Utilities – Tools to help database administrators manage the performance of Microsoft SQL Server. (link)
DiagManager – Graphical PSSdiag configuration manager. (link)
SQLNexus – Tool for PSSDiag data analysis. (link)
SQL Sentry Plan Explorer – Query analysis and tuning tool. (link)
Microsoft Data Migration Assistant – Tool for database compatibility issues detection. (link)
Microsoft Database Experimentation Assistant – Tool for evaluating a targeted version of SQL for a given workload. (link)

Other data platforms

DB Browser for SQL Lite – Data Management Tool for SQL Lite (link)
pgAdmin – Data Management Tool for PostgreSql. (link)
Neo4J – Graph Platform. (link)

Programming

git – Version control system. (link)
Git Extensions – Graphical User interface for git. (link)
TortoiseGit – Windows Shell Interface to Git and based on TortoiseSVN. (link)
Microsoft Visual Studio – Integrated Development Environment. (link)
Microsoft Visual Studio Code – Lightweight Code Editor. (link)
Notepad++ – Code editor. (link)

Frameworks

Java – Java Runtime Environment. (link)
.Net Framework – (link)
Microsoft SQL Server Data-tier Application Framework (DACFx) – (link)

Communication

Cisco Webex Meetings – Video conferencing and screen sharing. (link)
Skype – Video chat and voice calls. (link)
Slack – Collaboration tool. (link)

Miscellaneous – Work

7-zip – Great file archiver. (link)
Adobe Acrobat Reader – PDF Reader. (link)
KeePass – Passwords manager. (link)
Putty – SSH and telnet client for Windows. (link)
Total Commander – File manager for Windows. (link)
WinMerge – File differencing and merging tool. (link)
WinScp – SFTP, SCP, and FTP client for Windows. (link)
Microsoft PowerBI Desktop – For creating live, interactive reports. (link)
Remote Server Administration Tools – For remote management rolses and features in Windows Server. (link)
OneDrive – File hosting service. (link)
VirtualBox – General purpose Virtual Machines host. (link)
Microsoft Visio – Diagram and charts creation. (link)

Miscellaneous – Entertainment

K-Lite Codec Pack – Pack of video and audio codecs. (link)
BESTPlayer – Video player with subtitles support. (link)

Miscellaneous – Blogging and presenting

GIMP – Photo/Graphic editing program. (link)
Pain.NET – Photo/Graphic editing program. (link)
ScreenToGif – Screen, webcam and sketchboard recorder with an integrated editor. (link)
Sizer – freeware utility that allows you to resize any window to an exact, predefined size. (link)
ZoomIt – screen zoom and annotation tool for technical presentations. (link)

Wow… I have much more items on my list than I expected. However, I know this list may be not complete and some very valuable application may be missing here.

Drop a comment if you found this list useful or if you think I should try out some other software you already use for a long time.

-Marek

Share it:

I am speaking at 24 Hours of PASS

I’m happy to announce that I have been selected to present a session during next 24 Hours of PASS. This time the main topic is Cross-Platform SQL Server Management.

24 HoP is an exceptional online event that provides free training for database professionals. It’s 24 back-to-back hours webinar series that features a new 60-minute webinar each hour. The full schedule has already been announced on last Friday.

I will have a great pleasure to present my session about SQL Operations Studio – a New Multi-Platform tool for SQL Server Database Development, Administration, and Monitoring at 06:00 UTC on April 26.

Be sure to mark your calendar for April 25-26, for this edition of 24 HoP. Registration is already open.

I’d love to see you there!

-Marek

Share it:

T-SQL Tuesday #101 – The Essential SQL Server Tools in my stack

This month’s TSQL2sday is hosted by Jens Vestergaard (b|t) and the topic is about SQL Server tools that we, Database Administrators, Architects, and Developers use every day to work on our tasks.

It’s a great topic, isn’t it

Personally, I think that the tools we use are of great importance for our daily work. Many of you may disagree by saying that skills are much more important than tools. Of course, I completely agree with this statement. The knowledge, experience, and skills enable us to do our work even without proper tools. However, it doesn’t mean that software we use doesn’t matter. Many applications, utilities, and frameworks can automate and speed up our daily activities. Thanks to that we can achieve more in a shorter time. That’s the reason why I blog about various SQL Server tools quite often (see posts in Tools category).

The SQL Server tools I use

I don’t have a long list of fancy and unknown applications I use. I think that most of them are well known in SQL Server community. Nevertheless, I decided to describe them for you. Maybe you will find something interesting here…

Server and Database Management

The first, and probably the most used by me tool is SQL Server Management Studio (SSMS) (download). I think I do not have to present it to anyone. It’s Swiss Army Knife tool for SQL Server specialists. Before SQL Server 2017 it was an inseparable element of every release. Since version 16, it is a separate application with a short release cycle. Every few weeks, Microsoft releases a new version and each of them delivers some new amazing features like XE Profiler, Data Discovery & Classification, Vulnerability Assessment, Import Flat File Wizard, and many, many more. I cannot imagine working with SQL Server without SSMS.

Despite the fact that SSMS is so popular, Microsoft decided to create another tool for database professionals. SQL Operations Studio (SQLOps) (download) is a new application from Microsoft designed to make our life easier. It’s a free and open source data management tool that enables you to work with SQL Server, Azure SQL DB and SQL DW from Windows, macOS, and Linux. This light-weight multi-platform solution can be used for SQL Server database development, administration, and monitoring. I described it more in details in this post.

T-SQL Source Code Management

For database source code management, I use SQL Server Data Tools (SSDT) (download) and Git for Windows (download). Thanks to SSDT we can create SQL Database projects in the same way you can create .NET projects in Visual Studio. These projects can be built and validated, and then the compiled artifact in the form of a DACPAC file can be easily deployed against the target database.

To automate the DACPAC deployment process my team uses sqlpackage.exe from Data-Tier Application Framework (DACFx) (download) wrapped in our own PowerShell module. We decided to create our own wrapper because this gives us required flexibility and makes our database deployment process more streamlined.

For text/SQL files

SSMS and SSDT are great and very powerful SQL Server tools for work with *.sql files. However, sometimes I find that I don’t need to use such big and complex tool for performing easy and quick tasks on text/SQL files. It may include things like opening file just for a quick view or quick search. I used to use Notepad++ (download) for such kind of activities, but recently I’m trying to make myself more familiar with Visual Studio Code (download).

Visual Studio Code is a lightweight and extensible multi-platform source code editor which can be used on Windows, macOS, and Linux. Microsoft puts a lot of effort in the development of this solution. It comes with a built-in support for JavaScript, TypeScript, and Node.js and has a lot of extensions for other languages (such as T-SQL, C#, C++, Java, Python,…).

For text file comparison I use WinMerge (download). It is a free and an Open Source differencing and merging tool for Windows. It can compare both folders and files, presenting differences in a visual text format that is easy to understand and handle.

Database Unit Tests

To test database code I use tSQLt (download). tSQLt is a free and opensource database unit testing framework for Microsoft SQL Server, completely written in T-SQL and .NET CLR. Additionally, besides the long list of available assertions, it also has the great and rare functionality to mock various database objects. In my opinion that makes it better then tests in SSDT.

In addition to the above, I recently started to use SQLCover (download) created by Ed Elliott (b|t). It’s one more free and open source solution, this time for unit tests code coverage report generation. It’s amazing how well it works.

Community scripts/tools

Besides all of the above-mentioned SQL Server tools, I have my favorite set of well-known T-SQL scripts or procedures I use commonly for troubleshooting. The first and probably most-known solution is sp_whoisactive (download) procedure from Adam Machanic (b|t). It’s something like a powerful combination of sp_who2, Activity Monitor, and many other diagnostic queries based on DMVs. If you’ve never used it before, then you should try it now!

Other scripts I use quite often are stored procedures from Brent Ozar ULTD First Responder Kit (download). This bundle consists of such tools like sp_Blitz, sp_BlitzFirst, sp_BlitzCache, and a few others also very useful.

Troubleshooting Tools

In very difficult situations, when above scripts are not enough for issue troubleshooting, I use PSSdiag (download) and SQLNexus (download). Both were developed in Microsoft as side projects mainly used by SQL Server Customer Support Service and Product Support Service teams. Now, public versions are free and opensource and can be used by everyone.

PSSdiag is a data collector utility that can capture various interesting data sets, counters, and metrics. For example:

Event Logs
PerfMon counters
Server configuration
Error Logs
Profiler Trace / XE Session
Blocking information
Query statistics
and many others…

If that would not be enough it also can be extended by custom collector scripts. This gives the user the ability collect all the necessary information.

SQLNexus analyses the data collected by PSSdiag and generates very detailed reports that describe monitored SQL Server state and health. They are invaluable in troubleshooting SQL Server issues.

In case you’re interested in possibilities that these tools give, I encourage you to read my other blog post describing PSSdiag and SQLNexus use case.

SQL Server tools that are on my check-it-out list

In addition to all of these tools I already use, there are others I still want to try out.

dbatools (download) is a PowerShell module with more than 300 SQL Server administration, best practice and migration commands included. Thanks to the huge number of contributors from SQL Server community it’s growing and getting better and better.

The same amazing group of people created dbachecks (download) PowerShell module. It’s a solution for automated environment validation. It’s based on Pester and has already more than 80 checks implemented.

Last but not least is dbareports (download). It uses PowerShell, T-SQL and SQL Agent to gather information about your SQL Server estate. It also comes with beautiful SSRS reports and PowerBi and Cortana Integration.

All of these solutions wouldn’t exist without Chrissy LeMaire (b|t) and Rob Sewell aka SQL DBA with A Beard (b|t) who started all of this! Thanks to their and SQL Server community effort we have a plenty of great SQL Server tools for our use.

-Marek

Share it:

How to use Diskspd to check IO subsystem performance

One of many responsibilities of the Database Administrator is the installation of new SQL Server instances. However, before you do it, it is best practice to test IO subsystem performance. It does not make any sense to install the new instance in an environment that will have performance issues in a moment. In this blog post, I describe how to use Diskspd tool to perform such disk performance tests.

What is Diskspd?

Diskspd is a storage testing tool created by Microsoft Windows, Windows Server and Cloud Server Infrastructure Engineering teams. It combines robust and granular IO workload definition with flexible runtime and output options. That makes it a perfect tool for storage performance testing, validation and benchmarking.

Where to find Diskspd?

Diskspd is a free and open source utility. Its source code can be found on GitHub. The repository also hosts other frameworks which use Diskspd. You can find them under ‘Frameworks’ directory. A binary release is hosted by Microsoft at the following location: http://aka.ms/diskspd.

How to use Diskspd?

Diskspd doesn’t require any additional tools or frameworks to be used. No .NET or Java required. Everything that is needed is included in a ZIP file. After downloading it and extracting you will have this:

Each of three folders contains a Diskspd.exe executable:

amd64fre – for 64bit systems
armfre – for ARM systems
x86fre – for 32bit systems

In addition to that, you get a comprehensive Diskspd documentation with many usage examples and a PowerShell script to convert XML results into CSV.

Diskspd is a command line utility and as a such has a long list of available parameters. However, to use it efficiently you just need to remember a few of them. Let’s analyze parameters from the below example:

DiskSpd.exe -c150G -d300 -r -w40 -t8 -o32 -b64K -Sh -L D:\SpeedTest\testfile.dat

Parameters:

-c150G – Create a file of the specified size. Size can be stated in bytes or KiBs, MiBs, GiBs. Here – 150GB.
-d300 – Duration of measurement period in seconds, not including cool-down or warm-up time (default = 10 seconds). Here – 5 minutes.
-r – Random I/O access (override -s).
-s – Sequential I/O access.
-w40 – Percentage of write requests to issue (default = 0, 100% read). Here 40% of IO operations are Writes, remaining 60% are Reads. This is a usual load for my SQL Server OLTP databases.
-t8 – The number of threads per file. Here – 8. One thread per available core.
-o32 – The number of outstanding I/O requests per target per thread. In other words, it is a queue depth. Here – 32.
-b64K – Block size in bytes or KiBs, MiBs, or GiBs. Here – 64KB.
-Sh – Disable both software caching and hardware write caching.
-L – Measure latency statistics.
D:\SpeedTest\testfile.dat – My target file used for testing (created with -c).

How to read results?

I executed this command on a system I recently got for testing. My task was to examine whether new SAN disks array is configured properly and has sufficient performance for a load generated by SQL Server. Here is the result:

Command Line: DiskSpd.exe -c150G -d300 -r -w40 -t8 -o32 -b64K -Sh -L D:\SpeedTest\testfile.dat

Input parameters:

    timespan:   1
    -------------
    duration: 300s
    warm up time: 5s
    cool down time: 0s
    measuring latency
    random seed: 0
    path: 'D:\SpeedTest\testfile.dat'
        think time: 0ms
        burst size: 0
        software cache disabled
        hardware write cache disabled, writethrough on
        performing mix test (read/write ratio: 60/40)
        block size: 65536
        using random I/O (alignment: 65536)
        number of outstanding I/O operations: 32
        thread stride size: 0
        threads per file: 8
        using I/O Completion Ports
        IO priority: normal



Results for timespan 1:
*******************************************************************************

actual test time:	300.01s
thread count:		8
proc count:		8

CPU |  Usage |  User  |  Kernel |  Idle
-------------------------------------------
   0|   1.01%|   0.13%|    0.87%|  99.00%
   1|   3.04%|   0.14%|    2.90%|  96.96%
   2|   0.71%|   0.14%|    0.57%|  99.29%
   3|   0.74%|   0.13%|    0.61%|  99.26%
   4|   0.62%|   0.10%|    0.53%|  99.38%
   5|   0.90%|   0.09%|    0.81%|  99.10%
   6|   0.66%|   0.06%|    0.60%|  99.34%
   7|   0.62%|   0.05%|    0.57%|  99.38%
-------------------------------------------
avg.|   1.04%|   0.11%|    0.93%|  98.96%

Total IO
thread |       bytes     |     I/Os     |     MB/s   |  I/O per s |  AvgLat  | LatStdDev |  file
-----------------------------------------------------------------------------------------------------
     0 |      4326424576 |        66016 |      13.75 |     220.04 |  145.375 |    52.576 | testfile.dat (150GB)
     1 |      4338679808 |        66203 |      13.79 |     220.67 |  144.962 |    51.947 | testfile.dat (150GB)
     2 |      4328062976 |        66041 |      13.76 |     220.13 |  145.323 |    52.482 | testfile.dat (150GB)
     3 |      4328128512 |        66042 |      13.76 |     220.13 |  145.308 |    52.563 | testfile.dat (150GB)
     4 |      4336517120 |        66170 |      13.78 |     220.56 |  145.029 |    52.215 | testfile.dat (150GB)
     5 |      4334288896 |        66136 |      13.78 |     220.44 |  145.107 |    52.244 | testfile.dat (150GB)
     6 |      4328718336 |        66051 |      13.76 |     220.16 |  145.289 |    53.204 | testfile.dat (150GB)
     7 |      4339859456 |        66221 |      13.80 |     220.73 |  144.928 |    52.339 | testfile.dat (150GB)
-----------------------------------------------------------------------------------------------------
total:       34660679680 |       528880 |     110.18 |    1762.85 |  145.165 |    52.447

Read IO
thread |       bytes     |     I/Os     |     MB/s   |  I/O per s |  AvgLat  | LatStdDev |  file
-----------------------------------------------------------------------------------------------------
     0 |      2600796160 |        39685 |       8.27 |     132.28 |  144.647 |    58.771 | testfile.dat (150GB)
     1 |      2616066048 |        39918 |       8.32 |     133.05 |  144.026 |    57.697 | testfile.dat (150GB)
     2 |      2605776896 |        39761 |       8.28 |     132.53 |  144.203 |    58.723 | testfile.dat (150GB)
     3 |      2582183936 |        39401 |       8.21 |     131.33 |  144.362 |    59.017 | testfile.dat (150GB)
     4 |      2592538624 |        39559 |       8.24 |     131.86 |  144.037 |    58.435 | testfile.dat (150GB)
     5 |      2597126144 |        39629 |       8.26 |     132.09 |  144.168 |    58.460 | testfile.dat (150GB)
     6 |      2599616512 |        39667 |       8.26 |     132.22 |  144.713 |    59.531 | testfile.dat (150GB)
     7 |      2601058304 |        39689 |       8.27 |     132.29 |  143.783 |    58.635 | testfile.dat (150GB)
-----------------------------------------------------------------------------------------------------
total:       20795162624 |       317309 |      66.10 |    1057.65 |  144.242 |    58.661

Write IO
thread |       bytes     |     I/Os     |     MB/s   |  I/O per s |  AvgLat  | LatStdDev |  file
-----------------------------------------------------------------------------------------------------
     0 |      1725628416 |        26331 |       5.49 |      87.77 |  146.474 |    41.504 | testfile.dat (150GB)
     1 |      1722613760 |        26285 |       5.48 |      87.61 |  146.384 |    41.685 | testfile.dat (150GB)
     2 |      1722286080 |        26280 |       5.47 |      87.60 |  147.019 |    41.225 | testfile.dat (150GB)
     3 |      1745944576 |        26641 |       5.55 |      88.80 |  146.707 |    41.165 | testfile.dat (150GB)
     4 |      1743978496 |        26611 |       5.54 |      88.70 |  146.505 |    41.226 | testfile.dat (150GB)
     5 |      1737162752 |        26507 |       5.52 |      88.35 |  146.511 |    41.199 | testfile.dat (150GB)
     6 |      1729101824 |        26384 |       5.50 |      87.94 |  146.156 |    41.917 | testfile.dat (150GB)
     7 |      1738801152 |        26532 |       5.53 |      88.44 |  146.641 |    41.101 | testfile.dat (150GB)
-----------------------------------------------------------------------------------------------------
total:       13865517056 |       211571 |      44.08 |     705.20 |  146.550 |    41.379


  %-ile |  Read (ms) | Write (ms) | Total (ms)
----------------------------------------------
    min |     22.132 |     22.095 |     22.095
   25th |    111.940 |    129.764 |    116.858
   50th |    132.568 |    151.406 |    141.026
   75th |    163.575 |    172.090 |    168.590
   90th |    210.856 |    191.478 |    199.258
   95th |    251.512 |    203.980 |    226.995
   99th |    359.454 |    228.761 |    322.688
3-nines |    541.528 |    270.872 |    497.081
4-nines |    727.123 |    317.519 |    695.128
5-nines |    811.054 |    475.358 |    807.394
6-nines |    828.036 |    648.498 |    828.036
7-nines |    828.036 |    648.498 |    828.036
8-nines |    828.036 |    648.498 |    828.036
9-nines |    828.036 |    648.498 |    828.036
    max |    828.036 |    648.498 |    828.036

Let’s analyze it.

In the first line, we have the command which was executed to perform the test. Used parameters and any other settings are listed and explained below.

Command Line: DiskSpd.exe -c150G -d300 -r -w40 -t8 -o32 -b64K -Sh -L D:\SpeedTest\testfile.dat

Input parameters:

    timespan:   1
    -------------
    duration: 300s
    warm up time: 5s
    cool down time: 0s
    measuring latency
    random seed: 0
    path: 'D:\SpeedTest\testfile.dat'
        think time: 0ms
        burst size: 0
        software cache disabled
        hardware write cache disabled, writethrough on
        performing mix test (read/write ratio: 60/40)
        block size: 65536
        using random I/O (alignment: 65536)
        number of outstanding I/O operations: 32
        thread stride size: 0
        threads per file: 8
        using I/O Completion Ports
        IO priority: normal

In next section, we have the time of the test run, number of threads, and number of available processors. Additionally, we have information about the average utilization of every processor during the test run.

actual test time:	300.01s
thread count:		8
proc count:		8

CPU |  Usage |  User  |  Kernel |  Idle
-------------------------------------------
   0|   1.01%|   0.13%|    0.87%|  99.00%
   1|   3.04%|   0.14%|    2.90%|  96.96%
   2|   0.71%|   0.14%|    0.57%|  99.29%
   3|   0.74%|   0.13%|    0.61%|  99.26%
   4|   0.62%|   0.10%|    0.53%|  99.38%
   5|   0.90%|   0.09%|    0.81%|  99.10%
   6|   0.66%|   0.06%|    0.60%|  99.34%
   7|   0.62%|   0.05%|    0.57%|  99.38%
-------------------------------------------
avg.|   1.04%|   0.11%|    0.93%|  98.96%

As you can see there was almost no load.

The Total IO section provides statistics (Read+Write) per thread. The last row provides Total values for the whole test run.

Total IO
thread |  bytes     |  I/Os  |  MB/s  | I/O per s | AvgLat  | LatStdDev |  file
------------------------------------------------------------------------------------
     0 | 4326424576 |  66016 |  13.75 |    220.04 | 145.375 |    52.576 | testfile.dat
     1 | 4338679808 |  66203 |  13.79 |    220.67 | 144.962 |    51.947 | testfile.dat
     2 | 4328062976 |  66041 |  13.76 |    220.13 | 145.323 |    52.482 | testfile.dat
     3 | 4328128512 |  66042 |  13.76 |    220.13 | 145.308 |    52.563 | testfile.dat
     4 | 4336517120 |  66170 |  13.78 |    220.56 | 145.029 |    52.215 | testfile.dat
     5 | 4334288896 |  66136 |  13.78 |    220.44 | 145.107 |    52.244 | testfile.dat
     6 | 4328718336 |  66051 |  13.76 |    220.16 | 145.289 |    53.204 | testfile.dat
     7 | 4339859456 |  66221 |  13.80 |    220.73 | 144.928 |    52.339 | testfile.dat
------------------------------------------------------------------------------------
total:  34660679680 | 528880 | 110.18 |   1762.85 | 145.165 |    52.447

In this case, test generated 528880 IO operations, the average throughput was 110.18 MB/s (1762.85 IOPS) and the average latency was 145 ms. In short: Terrible!

Next two sections, Read IO and Write IO provides the same statistics but individually for the Read and Write operations.

The last section provides a detailed information about a latency. It is a summary table of per percentile latencies per operation type.

  %-ile |  Read (ms) | Write (ms) | Total (ms)
----------------------------------------------
    min |     22.132 |     22.095 |     22.095
   25th |    111.940 |    129.764 |    116.858
   50th |    132.568 |    151.406 |    141.026
   75th |    163.575 |    172.090 |    168.590
   90th |    210.856 |    191.478 |    199.258
   95th |    251.512 |    203.980 |    226.995
   99th |    359.454 |    228.761 |    322.688
3-nines |    541.528 |    270.872 |    497.081
4-nines |    727.123 |    317.519 |    695.128
5-nines |    811.054 |    475.358 |    807.394
6-nines |    828.036 |    648.498 |    828.036
7-nines |    828.036 |    648.498 |    828.036
8-nines |    828.036 |    648.498 |    828.036
9-nines |    828.036 |    648.498 |    828.036
    max |    828.036 |    648.498 |    828.036

The ‘nines’ refer to the number of nines: 3-nines is the 99.9th percentile, and so forth.

This is how PerfMon counters looked during this test run.

Testing scenarios

Of course, one single test run is not enough to thoroughly test IO subsystem. Especially in a situation when you have different drives to handle different workload types (or if you work with OLAP databases). One of the most common best practice is to store database data files and database log file separately. Such separation requires a different kind of testing for each drive.

Fortunately, Diskspd documentation provides a lot of helpful examples:

Data file patterns

100% 8KiB/64KiB Random reads – Large area of random concurrent reads of 8KB/64KB blocks. Disable both software caching and hardware write caching.

DiskSpd.exe -c1000G –d300 -r -w0 -t8 –o32 -b8K -h -L F:\testfile.dat

DiskSpd.exe -c1000G –d300 -r -w0 -t8 –o32 -b64K -h -L F:\testfile.dat

100% 8KiB/64KiB Random writes – Large area of random concurrent writes of 8KB/64KB blocks. Disable both software caching and hardware write caching.

DiskSpd.exe -c1000G –d300 -r –w100 -t8 –o32 -b8K -h -L F:\testfile.dat

DiskSpd.exe -c1000G –d300 -r –w100 -t8 –o32 -b64K -h -L F:\testfile.dat

60% 8KiB/64KiB Random READs, 40% 8KiB/64KiB Random writes – Large area of random concurrent 60% reads and 40% writes of 8KB/64KB blocks. Disable both software caching and hardware write caching.

DiskSpd.exe -c1000G –d300 -r –w40 -t8 –o32 -b8K -h -L F:\testfile.dat

DiskSpd.exe -c1000G –d300 -r –w40 -t8 –o32 -b64K -h -L F:\testfile.dat

Log file patterns

100% 64KiB reads – Large area of sequential concurrent reads of 64KB blocks. 8 outstanding IOs. Disable both software caching and hardware write caching.

DiskSpd.exe -c1000G –w0 -b64K –F4 -T1b -s8b -o8 –d300 -h F:\testfile.dat

100% 64KiB writes – Large area of sequential concurrent writes of 64KB blocks. 116 Outstanding IOs. Disable both software caching and hardware write caching.

DiskSpd.exe -c1000G –w100 -b64K –F4 -T1b -s8b –o116 –d300 -h F:\testfile.dat

40% 64KiB reads, 60% 64KiB writes – Large area of sequential concurrent 40% Reads, 60% writes of 64KB blocks. 8 Outstanding IOs. Disable both software caching and hardware write caching.

DiskSpd.exe -c1000G –w60 -b64K –F4 -T1b -s8b –o8 –d300 -h F:\testfile.dat

The results of my testing

If you are curious, I will tell you. I executed six test runs. I tested 8KB and 64KB block size operations against disk formatted with 4KB, 8KB, and 64KB per cluster. Each one with 60% reads / 40% writes ratio. Here you can find the average latency I got from my measurements.

Latency in ms
Test	Read	Write	Bytes per Cluster
8k_1	248.303	397.233	4k
8k_2	137.661	167.228	8k
8k_3	172.608	214.828	64k
64k_1	164.921	215.299	4k
64k_2	144.242	146.55	8k
64K_3	161.367	155.142	64k

If you don’t know yet how to interpret these results, I highly recommend you to read this post from Paul Randal (b|t). Here I will just paste a short cheat sheet:

Excellent: < 1ms
Very good: < 5ms
Good: 5 – 10ms
Poor: 10 – 20ms
Bad: 20 – 100ms
Shockingly bad: 100 – 500ms
WOW!: > 500ms

Yeah… Shockingly bad… This disk is trash. I need to write one more email to the storage team.

-Marek

Share it:

I will speak at SQLDay 2018 conference

I am pleased to inform you that this year I will have the opportunity to speak at SQLDay conference. This is already a second time I will participate in this wonderful event as a speaker. It is a great feeling to know that I will meet some of you soon.

About SQLDay

SQLDay is a biggest Microsoft Data Platform related conference in this part of Europe. It will take place in Wrocław, Poland on May 14-16. It is a three-day event – one day of full-day workshops and two days of sessions. For 800 of participants, the organizers prepared 6 great workshops and 50 sessions in 5 different tracks. This year it will be a great opportunity to meet such industry experts like Kalen Delaney (b|t), Niko Neugebauer (b|t), and Itzik Ben-Gan (b|t). But that’s not all, it’s just beginning of a very long list of speakers. This year, you will also see a strong representation of Microsoft Azure community there.

About my session

Last year, I was presenting tSQLt framework for database unit testing. This time, I will talk about Query Execution Plans. I will explain how they are created, how to get them, and what useful information they provide. In addition, I will discuss few most important operators and its properties. This knowledge is extremely useful when analyzing query performance problems. Of course, everything will be supported by interesting demos. I encourage you to come and see my session.

If you would like to know how it was a year ago, look at the video below.

-Marek

Share it:

QuickQuestion: Can I mock a table in another DB using tSQLt?

QuickQuestion series is a series of short posts in which I answer database related questions asked by my colleagues, friends, and co-workers, mainly application developers.

Today’s question:

Can I mock a table in another database using tSQLt?

Continue reading “QuickQuestion: Can I mock a table in another DB using tSQLt?”

Share it:

Book Review: Migrating to Microservice Databases

At the end of the year 2017 in this blog post, I wrote my goals for 2018. One of them was to read books I have on my to-read list. One of those books is “Migrating to Microservice Databases: From Relational Monolith to Distributed Data”. It’s a free book published by O’Reilly Media. You can get your copy here. I just finished reading this ebook and I want to share some of my thoughts with you.

This technical book is a quite short one (71 pages total). It’s written by Edson Yanaga – Red Hat’s Director of Developer Experience, who describes microservices architecture from the database point of view. As books title suggests, its main topic is migration strategies you can use to break huge monolith database into few smaller ones. Besides that, it also touches on the subject of zero downtime deployments.

Microservices

High cohesion and loose coupling.

Microservice architecture assumes that each of developed services serves separate and specialized functionalities, but they all together form one product. On the other side, each service should be as much independent of others as possible. The situation becomes way more complicated when we start to consider services that use databases…

Each microservice should have its own separate database.

On the first look, databases do not seem to be a problem, but the longer we think about it, about the architecture, about data modifications, duplication, synchronization, and overall product performance, the more problems we can see. Databases may be separated, but data in most cases are common for some of the services.

The book

I think this book is a good introduction to microservices’ databases topic. Especially for database specialists for whom this architecture may not be well known. It explains advantages and disadvantages of the microservices pattern, and stress problematic aspects of databases. The author lists the nine possible database migration strategies, from shared tables to virtual databases, and event sourcing, giving readers a lot of choice in what to implement. Each strategy is actually a data synchronization technique for multi-database environment that we can use in other scenarios – not only for microservices. The book explains well all their pros and cons. However, I need to admit that during the reading, I was missing detailed implementation examples for some hard cases (preferably with code samples).

Who is this book for?

If you already know microservices pattern and you work with databases that support microservices, then probably this book is not for you.

However, if you just were at a meeting where your boss announced that microservices architecture pattern is on the application roadmap and you have no idea what he is talking about, then you should consider reading this book as soon as possible. Maybe it will not equip you with ready-to-implement solutions, but it will give you a general idea of what is possible for your databases.

-Marek

Share it:

SQL Graph Database – the new feature in SQL Server 2017

SQL Server 2017 introduced a lot of new features. One of the most surprising is Graph Database capabilities (aka SQL Graph and Graph Extensions). This new functionality enables users to model complex relationships using new database objects and queries. Let’s see what it is and how it works. Continue reading “SQL Graph Database – the new feature in SQL Server 2017”

Share it: