Posts Tagged ‘Windows Server’

Enabling Hyper-V Dynamic Memory in Windows Server 2008 R2

Last week saw the release of Windows Server 2008 R2 Service Pack 1 and with it one of the feature’s I’ve been waiting for – Hyper-V Dynamic Memory.  Until now if you were running a Hyper-V host with (for example) 16GB of RAM your guests could never exceed that amount, e.g. you could have 4 x 4GB, 2 x 4GB + 1 x 8GB, etc. but never more than 16GB in total. 

With the addition of Dynamic Memory you can finally over-commit RAM enabling you to make better use of available resources, as with CPU usage you still need to balance your workloads carefully and it only really makes sense to combine workloads that have high memory pressures at different times otherwise you could end up with poor performance or experience system failures when memory is unavailable. 

Please note that Dynamic Memory is configured on a host-by-host basis so nothing will change until you follow the process below, Microsoft have a really helpful TechNet page explaining how to configure Dynamic Memory but in a nutshell you should follow these steps…

Update both the Host and the Guest to Windows Server 2008 R2 SP1 then use Hyper-V Manager to connect to the Guest then choose Action >> Insert Integration Services Setup Disk and reinstall the integration components. 

Shut down the Guest and in Hyper-V Manager right-click on the guest and pick Settings in the memory panel choose Dynamic then set the Startup RAM and Maximum RAM.  There’s also a configurable buffer percentage (Hyper-V reserves this extra amount but will give it up under pressure).  I’d leave it on the default 20% unless you’ve got a good reason not to. 

Set  a priority for this guest (e.g. you could set this higher for servers that could fail with too little memory). 

Restart the guest and check in Hyper-V Manager…

Here you can see that I’ve exceeded my Startup memory of 2GB but only have a current demand of 1795MB and since there’s no memory pressure on the host the status shows as OK.  If the host is unable to reserver the entire buffer amount (in my case 20%) the status will show as “Low” and if the host is unable to allocate any buffer it will show “Warning”.

Using 32-bit Task Scheduler + CScript on Windows 2008 R2

One of my primary data sources for Business Objects is a replicated pair of MySQL servers where I am asked by the DBAs to report against the slave however during maintenance replication can fall behind and reports that require up-to-date data will be incomplete.  Since we don’t live in an ideal world we can’t always plan our maintenance windows so I wrote a small VBScript routine that will detect the replication delay and if if it exceeds a threshold will change the ODBC source to point to the master. 

If you’ve caught my earlier article on 32-bit ODBC Drivers in Windows Server 2008 R2 you’ll know that there’s plenty of fun to be had since my ODBC drivers are 32-bit.  This means that I need to run the VBScript using the 32-bit version of CScript and the schedule it using the 32-bit Task Scheduler and once again the solution is to use the 32-bit tools provided in the SysWOW64 directory….

• C:\Windows\SysWOW64\cscript
• C:\Windows\SysWOW64\taskschd.msc

Beyond that you shouldn’t have too much trouble but if you do please leave a comment below with details and I’ll get back to you if I can help.

Quick Tip: Run As Different User in Windows 7 + 2008 R2

If you need to run an application using the credentials of a user other than yourself (or the one you’re logged-in as) in Windows 7 or Windows Server 2008 R2 (may work in other versions) all you need to do is hold shift as you right-click on the application. 

For example, in this case I would like to launch Windows Explorer as a different user…

32-Bit ODBC Drivers in Windows Server 2008 R2

Lately I’ve been taking advantage of my MSDN subscription (thanks to Ken Simmons‘ competition last month) and playing with some new technologies, initially experimenting with Windows Server 2008 R2. If you hadn’t heard prior to launch period, Microsoft made 2008 R2 64-bit only – probably the right decision to make but whilst the software industry is still making a transition from 32-bit to 64-bit there are bound to be some niggles here and there.

Being a database guy, one of the issues I noticed right away was that the ODBC Data Source Administrator accessible via Control Panel / Administrative Tools is the 64-bit version and can only be used to setup connections for 64-bit ODBC drivers. Not only was the 64-bit version missing the Postgres driver I had just installed, there were no drivers at all other than SQL Server…

It turns out that there are are two, entirely identical ODBC tools and the one that most of us will end up using initially (unless we’re lucky enough to have an all 64-bit architecture) is kept in the basement that is the c:\Windows folder. The 32-bit ODBC Data Source Administrator can be found by going to the Start Menu, selecting Run and executing c:\Windows\SysWOW64\odbcad32.exe as follows…

Once launched, you’ll see a tool that appears to be identical in every way, except that the ‘missing’ ODBC drivers are now available…

Please note that you can’t run both 32-bit and 64-bit tools at the same time so please make sure you close the 64-bit one first, it’s also worth bearing in mind that if you’re running 32-bit applications they will probably be looking for 32-bit DSNs so even if you can get a 64-bit driver for your data source it doesn’t mean that it’s the right thing to do.

As much as I understand Microsoft’s decision to stop developing 32-bit operating systems, a little bit of a helping hand during the transition period would’ve been nice - perhaps a second shortcut in the Administrative tools folder and the ability to run them simultaneously?  The whole thing seems like a confisuing mess in their own words…

The 32-bit version of the ODBC Administrator tool displays 32-bit system DSNs, 32-bit user DSNs, and 64-bit user DSNs. The 64-bit version of the ODBC Administrator tool displays 64-bit system DSNs, 32-bit user DSNs, and 64-bit user DSNs.  

To maintain backward compatibility, no resolution for this problem is currently available… to work around this problem, use the appropriate version of the ODBC Administrator tool.

I’ve made my own shortcuts to the 32-bit version and if you’re like me and constantly diving in and out of ODBC Administrator then you’ll probably want to do the same.

What’s New in Windows Server 2008 R2

I’ve never been much of a server admin but in order to install a fresh copy of SQL Server 2008 R2 (November CTP) I decided to install a fresh copy of Windows Server 2008 R2.  I downloaded the install from Microsoft’s site and because I’ve been primarily running on Windows Server 2003 I ran through one of their e-Learning sessions to fill in the blanks of what’s new in both R2 and Server 2008.

The main versions are:

• Foundation (up to 8GB RAM, 1 Socket, no VMs)
• Standard (up to 32GB RAM, 4 Sockets, Host + 1VM),
• Web Server (up to 32GB RAM, 4 Sockets, no VMs)
• Enterprise (up to 2TB RAM, 8 Sockets, Host + 4VMs)
• Data Centre (up to 2TB RAM, 64 Sockets, unlimited VMs)

As always there are lots of new features on the list but the biggies seem to be Hyper-V, Remote Desktop Services (RDS) and Virtual Desktop Infrastructure (VDI).  The most stark break from the past here is that 2008 R2 will only run on 64-bit processors, existing users of Server 2008 32-bit installs on 64-bit processors will not be able to perform an upgrade and will have to do a clean install.

Hyper-V is Microsoft’s new virtualisation technology which on paper seems like a good challenger to VMWare ESX and it comes with R2 as standard although you’ll need Enterprise or Datacenter  to make the most of it.  By far the coolest feature of Hyper-V is the Live Migration (similar to VMWare’s VMotion), this allows you to move a guest system from one host server to another without any interruption to the users of the guest, that’s it – zero downtime.

RDS and VDI represent an enhancement of Terminal Services, along with Hyper-V you can now host virtual desktops on a virtual host and permit access from approved devices over the web or via the network, remote desktop now supports multiple monitors and Aero-Glass.

The session mentioned a number of other features, most noteworthy wew BranchCache (WAN optimisation), DirectAccess (seamless and interventionlessVPN replacement) and PowerShell 2.0 (command-line server admin) an there was an incremental 7.5 release of IIS.

Well, I hope you got something from this post, more details and a link to the e-Learning session can be found on Microsoft’s Windows Server 2008 R2 microsite.