Just because you can - should you?

This is a question that all administrators must ask themselves at any point in time.

I have know quite a few very creative IT folks in my time, and we can all come up with very clever ideas, combinations, and adaptations of technologies.

Part of my role is to question why.  It is actually part of my job.

I frequently come across things I read by folks and I just think to myself, why the heck would you do _that_?  Just because you can? 

When I worked as an administrator I quickly learned the user dictum:  “Because they can, they will”

Yes, this is generally said in a demeaning way, referring to users, when administrators talk to each other, to their managers, or to folks that write software.

I still say this over and over to the developers I work with.  Generally framed with a statement like:  “If you don’t want them to do that..” or “Of course I entered 300 characters into that field” or “there was no error checking to stop me”.

Think about that as you apply technology or attempt to break technology.  It is all about the intent.

Are you intending to break it?  Do you just not know any better / or not understand it?

If you don’t understand it, then read and ask questions.

As a person who tests software – I absolutely say, yes do it.  But do it in a controlled and smart way.  Pay attention to the entire environment, not just the buttons you are clicking on.

It is usually the greater environment where the real bug exists.

The response that the WS-Management service computed exceed the internal limit for envelope size.

I have been hiding in PowerShell and WSMAN land for quite a few weeks now.  And each time I set up a new client machine or I scale out the number of VMs in my environment I run against this error:

Exception calling "Enumerate" with "1" argument(s): "The response that the WS-Management service computed exceed the internal limit
for envelope size. "

What am I doing?  Well, right now I am calling an enumerate class through WSMAN and listing all of the VMs that I have on a hypervisor.

Why do I get the error?  I know why, it is because the return string is so freaking large that the client side of WSMAN (the WinRM listener on my client PC where I am running the query from) says: “hey, my allocated buffer is full and you are trying to feed me ‘just one more wafer thin mint’”

Instead of exploding all over the place I get this nice, friendly warning.

How do I tweak my client to increase the receive envelope size?

Open an elevated command prompt (run as admin) and type:

winrm set winrm/config @{MaxEnvelopeSizekb="1024"}

Note = you do not need to set yours to 1024, I just set it higher than the default.

This was the last setting I had, but I need to go higher as I add more and more VMs.  One to 2Mb I go…

FreeNAS as a storage target for simple testing

Working with various hypervisors I frequently have a need for various types of storage volumes.

We can always use local storage for testing, but how do you handle a cluster of Hyper-V Server or a Pool of XenServer hosts?

I have used a variety of services.  Right now in the lab I am running Windows Storage Server 2008 to present NFS volumes and StarWind to present iSCSI volumes (I found StarWind iSCSI far easier to get working with XenServer than the iSCSI target add-on to Storage Server).

Mind you, I don’t need any of the enterprise bells and whistles that Storage Server gives me, I simply need storage.

Just the other day someone pointed me to FreeNAS.  Hey, a storage system that can present many different types of volumes.  FreeNAS is built upon FreeBSD and is bundled as a LiveCD ISO that can be installed to a hard disk, USB, or run as a LiveCD.

FreeNAS can do NFS, SMB, iSCSI, iTunes, FTP, TFTP, SSH, UPnP, BitTorrent, and other sharing protocols – from that standpoint it is pretty slick.

I must say that other than dealing with having to learn the UI – I have been pleasantly surprised at how well it is working.

Mind you, I am running FreeNAS in a VM.  That VM is hosted by Hyper-V.  And I have a XenServer that is accessing the LUNs being presented by the NAS device.

At the moment I have an iSCSI LUN and an NFS volume presented.  the big limitation that I currently have is that I can only have 4 IDE devices on my Hyper-V VM that limits me to one virtual disk for install, and three for serving as storage LUNs.

My VM simply runs with 512 Mb of RAM and a Legacy NIC.  The rest involved about an hour of figuring out how to install and configure the LUNs. 

Very little overhead and the storage actually ran pretty well when deploying a XenServer VM to the NFS share.  I really can’t argue.

When it is time to upgrade my current lab test storage server I think I will have to boot into the LiveCD and see if FreeNAS can identify the really old adaptec SCSI card and Compaq storage array.  If it can, it will win moving forward as Server 2008 R2 no longer has drivers for my really old Adaptec SCSI card – making the antique array useless. 

But that array is not useless, I just wouldn’t trust it for anything important.

The next step might be trying to build it into a paravirtualized VM for use on XenServer.  Since it sees the XenServer virtual devices as QEMU devices, I know that the kernel is Xen aware…

VHD CSV CORE and RDS article updates

Every now and then the individual teams at MSFT put out some really useful blog articles.

What are VHDs?

http://blogs.technet.com/windows_vpc/archive/2009/11/24/virtual-hard-disks-vhds-in-windows-virtual-pc.aspx

 

Creating a Virtual Machine to be stored on a Cluster Shared Volume

http://blogs.technet.com/askcore/archive/2009/11/30/creating-a-virtual-machine-to-be-stored-on-a-cluster-shared-volume.aspx

Windows Server 2008 R2 Live Migration – “The devil may be in the networking details.”

http://blogs.technet.com/askcore/archive/2009/12/10/windows-server-2008-r2-live-migration-the-devil-may-be-in-the-networking-details.aspx

 

The “CORE” configurator:

http://blogs.msdn.com/virtual_pc_guy/archive/2009/12/03/core-configurator-2-0.aspx

 

Remote Desktop Services Script Center

http://blogs.msdn.com/rds/archive/2009/11/04/announcing-the-launch-of-remote-desktop-services-script-center-to-ease-management.aspx

IT needs a language

I constantly struggle with writing documentation and also communicating concepts to many IT folks in writing. 

This is one of the reasons that has driven me to producing videos and capture sessions over the past couple years (I can say far more, more accurately with combined speech and visuals than attempt to accurately convey in writing).

My work as a moderator of the Hyper-V TechNet forum also speaks to this.  I spend a great deal of time describing concepts in forum posts – that end up being incredibly long.  Each time I write it a bit differently, still trying to convey a concept.

The reason for this post?  Accuracy.  Accurate conveyance of information.

This all started with a recent trip to the doctor.  20 minutes of discussing things with my doctor was summarized into a single paragraph of Latin.  The use of the common language of Latin to describe symptoms, and convey that description from doctor to doctor.

I am not proposing that Latin be revived in IT.  However, to use commonly understood grammatical structure to describe concepts, or installations, or topology, or systems architecture.

This gets even more complex as we move into the virtual workload world.  Where we describe physical characteristics in a non-physical way.

A virtual appliance for example.  In its most common representation today, this is a virtual machine – installed within that virtual machine is an operating system and some application.  The application and OS have dependencies – DNS, networking, Active Directory authentication for example.  The machine has dependencies – two virtual NICs, one public facing, one that faces a private subnet that connects to the database server.  Oh, and now we have an external entity of a database server.  Where does it all end – I don’t know of a single workload that exists in an enterprise as a single entity.

The struggle is:  How do we describe this in a universal way so that no matter where you take that appliance the environment knows what to do with it?  How to configure it.  How to connect it.  Where to connect it.

This is the role of a Standards Body – in this case the DMTF is attempting to build this common term framework.  But this is a framework, it is not universal terms – it is simply items or entities.  So at least we begin with common items – however describing them in different languages by vendor.

Now, how do I take that DMTF developed structure and tern it into words.  One set of words that can be used in association with a NIC to describe its network connection and then the attachment and VPN attributes.

Or, throw that idea out the window and focus on describing the interactions between the workloads only.  Don’t describe the physical topology in any way – simply describe the dependencies between workloads or appliance entities.

Most IT folks would never see this description language – but integrators would find it useful, documentation folks would find it useful, and even developers would find it useful.