Voice of the DBA

Tag: syndicated

Powershell in a Month – Day 19 – I/O

This is part of my Powershell Challenge, to learn more about PowerShell (PoSh) using the Learn Windows Powershell 3 in a Month of Lunches book by Don Jones.

Not the I/O that we think of in T-SQL, but more the I/O that’s a part of many programming languages. This reminds me a bit of C, with the explanation of how the powershell environment interacts with the user. It’ s not standard in and out, but it’s close.

This chapter also feels like it was written by a different author than some of the previous chapters. The chapter goes into some of the ways in which output commands interact with the shell, and how some do not. For example, the difference between Write-Host and Write-Output. The chapter uses diagrams of the pipeline to explain this. I was surprised that these diagrams weren’t used earlier in the discussion of the pipeline and how objects and data can flow through the pipeline. That’s a big omission from my point of view. I have a good idea of what a pipeline is, but the diagrams would have made it easier for many other people to understand what a pipeline is.

In any case, this chapter mostly deals with the relationship between the input and output and the PoSh process. There are mentions of the separation and how other editors might deal with the input and output differently, but not good examples. In some ways, I found this chapter a bit lacking. In a few sections, it seems that the prose is devoted to more about what not to do than what to do and how to build I/O interaction with the user.

The lab wasn’t great and overall, I didn’t like this chapter very much. Felt a little confusing about how I use this information.

March 3, 2014
Powershell in a Month Day 18–Variables

This is part of my Powershell Challenge, to learn more about PowerShell (PoSh) using the Learn Windows Powershell 3 in a Month of Lunches book by Don Jones.

I’m slightly behind here after holidays and some travel. Apparently my pop-up reminder for my own studies bears about as much value as quite a few other reminders that appear from people at work.

I’ve had to deal with variables in any number of languages in my career: BASIC, Pascal, C, C++, Java, C#, VB6, VB.NET, Foxpro, T-SQL, and a few more. I thought this chapter would be simple and it certainly started out that way, but I learned a few things and was pleasantly surprised.

NOTE: The editor here is substituting left and right quotes, and left and right double quotes as part of formal writing. In executing this code, the normal straight quote and double quotes are needed in PoSh.

The chapter starts out with the simple stuff, assigning values to variables. Unlike most languages,we don’t need to declare variables. You need one, just use it.

$domain = ‘SSCLab’

I’ve done this quite a bit in some of the practice for this series, but also in setting up my virtual lab. However I wasn’t sure why single and double quotes matter. If you’re not sure, this this:

$computer = ‘Tiny’

$Phrase = ‘Computer: $computer’

$phrase

and then this

$computer = ‘Tiny’

$Phrase = “Computer: $computer”

$phrase

You’ll see a difference. The first produces

Computer: $computer

The second actually does substitution and produces

Computer: Tiny

That means that you really need to pay attention to which set of quotes you are using in code. That’s an area I need to be careful. I also learned about the backtick as an escape character, but that’s an easy one as it’s similar in lots of languages to escape things out for newline and other special characters.

What’s interesting about PoSh variables, and probably one of the more powerful things, is that the variables can contain objects. That’s big. It’s like being able to overload classes into variables easily and quickly. I’m sure the exercises just scratch the surface, but it’s cool.

The lab was easy, just getting a job running and putting results in a variable. A combination of a few of the last few chapters.

February 28, 2014
Virtual Lab – Setting up a new VM

This is part of a series where I set up a virtual lab for testing and misc. work. The other parts in the series are here: Building a Virtual Lab with Hyper-V.

I have my disks set up, now it’s time to create my virtual machines. I’m going to show you how to create one, but all really are done the same way. The names change, but no matter what my purpose is, this is how I set up the VMs. Once this is done, I’ll use other posts to go into the customizations for each machine.

We’ll start in Hyper-V manager, selecting a new VM.

After the welcome screen, you need to name your VM and choose a location. I’ve got a folder set up for this lab on my machine, so I choose that, and set the name (for this machine) as DenverDC. This will be my domain controller and the first machine I set up.

Next we assign memory. I’ll want more for the SQL Servers, but this is easily changed at a later date, so I’ll leave this alone. One of the advantages of Core is less memory needed, and I could probably get by with less, but since I have 24GB on the host, I can spare half a gig.

After memory comes the networking. As you can see, I have a number of choices. The "WholeWideWorld" is the connection some of my VMs use to access the internet. In this case, I’m choosing the Internal network, which is the Internal switch I have set up. This is limited to connections between the VMs and since I want this to be an isolated network, this works fine.

My internal switch is actually configured as follows:

Now we need to set storage. Since I set up my disks before this and named them in a way that I can understand, I choose the one I need. The default here is a new hard disk, but I’m saving space with differencing disks.

I get a summary. Please check this as you set things up. Note that my differencing disk is set.

I click finish, and I have a VM. I start it up from Hyper-V Manager and connect.

Inside of Windows, I get the familiar Windows start screen (for Win8/WS2012). I click CTRL+ALT+DEL (leftmost icon on the toolbar) and then get prompted to change my password

I change it,and I’ll use the same admin password on this machine that I use on a number of VMs.

NOTE: This is NOT the password I use for any other services, including my VMWware VMs. At all. It’s only for Hyper-V VMs, but since I may have a few generations of VMs, I don’t want to forget this password. I also may end up starting up a few random VMs for talks, so I need to be able to get in.

Once I log in, I get a basic session. Not much in Core.

The only thing I really want to do here is rename the computer. I need to do more, but those will be in other posts. Let’s get the hostname.

I could start server config (sconfig.exe) and get a basic setup, but I wanted to play with my PowerShell knowledge. So I started PoSh, and Google helped me find the computer name. I also used Google to find out the rename.

The computer name (hostname) comes from

$env:computername

It doesn’t make sense, so I rename it with

Rename-Computer -Newname "DenverDC"

Once this machine restarts (Restart-Computer), it will have a new name.

I know that I could use sconfig and it’s fast, or click around on my Standard servers and rename the machine, but once I get used to typing these commands in Powershell, it’s very, very quick.

Note that my disks have been updated with changes. Their sizes have grown from the original 4MB.

I repeat this process for all the other machines, just to get them set with a password and name. Once they’ve rebooted, they’re ready for the next step.

February 27, 2014
Virtual Lab – Creating Differencing Disks

This is part of my series on building a virtual lab for use with SQL Server and Windows. You can see the entire series here: Building a Virtual Lab with Hyper-V.

The whole point of virtualization is better use of resources. Whether it’s CPU, storage, networking, power, etc., we are trying to save having to purchase 5 or 6 machines and connect them all, pay for them, etc. It’s much, much easier to use virtualization.

This is especially true of storage. When we build a lab, we don’t want to have to allocate a ton of space for our systems. In my case, for my design, this is what I want to end up with.

From my last post, I had the bottom two files already set up. These are my installations of Windows Server 2012 R2 Standard and Core, sysprep’d and ready to use.

Differencing – Saving Space

The idea in differencing disks is similar to the snapshot feature I used in VMWare to do this same process. I take a base disk, and create a “copy” of it. Except the copy doesn’t have everything from the base disk. Like a database snapshot in SQL Server, if I need to read something that’s in the base disk, I reference that. If I change something, or add something, I read from the copy.

As you can see above, I have 5 small disks at 4MB and my 2 large base disks. Each of the small disks is a differencing disk off either the Standard or Core base installations.

I created these by selecting New Hard Disk in Hyper-V Manager

After the intro screen, I make sure I’ve picked VHDX.

At the next screen, I choose the differencing option.

Now I need to pick a location for the copy. On my setup, I’m trying to keep this lab contained, so I have a WS2K12 Lab folder. I choose that as my location for the differencing disk. I give it a name, in my case, I’m using “Function” concatenated with the name of the Windows host. As seen below, my file server will be named “FileAvalanche.vhdx”.

Next I choose the parent disk. this is the base image. Depending on what I had in my design, I choose the Standard or Core images for various machines.

I get a summary where I can see all my options, and then click finish.

I do this five times and all of a sudden I have a lab.

A few things. Use some naming convention so you can tell which disk is which. Also, make sure you stick things in a location. I set a specific folder location for my VMs and disks, and then altered the Hyper-V Manager settings to default to this folder. On my machine that’s D:\Virtual Machines.

That helps me keep things contained, and it also means that when I want to copy a VM for a backup or to another machine, it’s easy.

February 20, 2014