Making groups of logical disks – an example from simple to advanced

I have been seeing this question come up a lot lately – as customers try and create groups of their disks – in order to create overrides for “certain” disks.  So – I am creating this post to give some real world examples.

Well – I will start this simply.  Say we want to create a group of all logical disks, with the drive letters of C: and D:?
I would start with creating a new group – and adding the “Windows Server 2003 Logical Disk” class.  Now – I could just use the parent class of “Logical Disk” instead of the OS specific class if I wanted.  The only issue with that is that most monitors targeting a disk – are OS specific – and duplicated three times.  So it is best to create specific groups for these – but totally not required.

Ok – so in the Dynamic Members query builder – I click add, and pick a property.  Since I know “Device Name” contains the drive letter – this will do nicely.  I select device name “Equals” “C:”. 


Now – I want to also include D:.  There are many way to do – this – and I will go through them.  First – I could simply Insert a new line for Windows Server 2003 Logical Disk – and replicate the line I have – adding one for D:



Only one problem – this is an “AND” grouping – I really need this to be an “OR” grouping to include both C: and D: drives.  You can switch this grouping the in UI, just right click the word “AND” and change it to an OR grouping:



Voila!



This formula now looks like: 

( Object is Windows Server 2003 Logical Disk AND ( Device Name Equals C: ) OR ( Device Name Equals D: ) )

Save your group – then right click it – and choose “View Group Members”.  This will ensure we are cooking with gas.  It should contain all your Windows 2003 based C: and D: volumes.



So far – so good.
Now – what if I ONLY want C: and D: disks, that are HOSTED by specific Windows Computers?  I can do that too!  Lets say I want a group – of all the C: and D: logical disks, on servers that begin with the name “SR______”
If you look at the bottom of the list of properties for Logical Disks – you will see (Host=Windows Computer).  From here – we can pick any attribute of the Windows Computer class as well to add to our expression – to limit our logical disks in our group to very specific Computers. 




Go back to the properties of your group, edit the Dynamic Members, and you can construct something like this:



Which translates to the following formula:

( Object is Windows Server 2003 Logical Disk AND ( Windows Computer.NetBIOS Computer Name Matches wildcard sr* ) AND ( ( Device Name Equals C: ) OR ( Device Name Equals D: ) ) )

Now – I will be honest – getting all the “ands” and “ors” in the right place using the UI is a big pain.  It is very easy to screw it up.  I like to simplify this to the fewest lines possible – using Regex.
Using Regular Expressions – we can use modifiers to create very advanced expressions.  my favorites are ^ which means the beginning of a new line or word, and | which is the “pipe” symbol – which means “or”.

So a simple way to accomplish the same example above – without all the complexity – is this:



WAY simpler!
However – you might notice – this doesn't work right.  This is because Regex is case sensitive.  If the Server NetBIOS name is detected in all CAPS, this expression wont match.  I talk a little about this issue in this post:  http://blogs.technet.com/kevinholman/archive/2009/04/21/quick-tip-using-regular-expressions-in-a-dynamic-group.aspx
So – based on that posts example – there is a simple way to make a RegEx case insensitive:  (?i:blah)
Using that as an example – we can now make very advanced groupings, quite easily:



(?i: to make it case insensitive.  ^ to signify the beginning of the word/line match.   Here is the formula now:

( Object is Windows Server 2003 Logical Disk AND ( Device Name Matches regular expression (?i:^C|^D) ) AND ( Windows Computer.NetBIOS Computer Name Matches regular expression (?i:^sr) ) )

Check it out:



Victory!

What if I wanted all logical disks that we NOT hosted by a Virtual Machine?  Easy!

( Object is Logical Disk AND ( Windows Computer.Virtual Machine Equals False ) AND True )

This reveals a group of ALL logical disks hosted by a Windows Computer with the attribute of Virtual Machine = False:



As you can see – using the Hosting relationship of the disk – to the Windows Computer object, there is much more you can do with groups.