Rob Broughall's blog

Exchange 2010 MCM videos

Rob Broughall — Fri, 25 Mar 2011 15:58:24 +0000

A few official videos have been produced by the Exchange MCM team, well worth a look if you’re considering attending (which you should because it rocks):

Detail from Bojan on his thoughts heading into the MCM:

http://borntolearn.mslearn.net/careerfactor/b/bojan/archive/2011/03/18/bojan-s-story-starts.aspx

Video featuring a number of instructors for the programme (& a view of the classroom – where you’ll live for three weeks J):

http://vimeo.com/21215132

A section of the transport content delivered by Brian Reid:

http://blogs.technet.com/b/themasterblog/archive/2010/12/28/mcm-exchange-video-preview.aspx

Rob

PowerShell to assign permissions to home directories

Rob Broughall — Fri, 25 Mar 2011 10:50:31 +0000

I have a situation where user data is migrating from one forest to another and there is a need to set permissions on folders which will form home ‘drives’ for users. The users’ home directory names match their SAM account names, I have written a simple PowerShell script to assign full control NTFS permissions to those folders based on the name of the user.

#script to give full control NTFS permissions on a directory to the domain user with the same name of that directory

#script settings

$domain = “robsdesk”
$root = “c:\data”

#don’t edit below here
$folders = Get-ChildItem $root
ForEach ($folder in $folders)
{
$username = $domain+“\”+$folder

$permissions = Get-Acl $folder

$userpermissions = New-Object System.Security.AccessControl.FileSystemAccessRule($username,“FullControl”, “ContainerInherit, ObjectInherit”, “None”, “Allow”)

$permissions.AddAccessRule($userpermissions)

Set-Acl $folder $permissions

Write-Host“Set permissions on $folder for $username”

}

The two lines to edit are the $domain and $root lines, the $domain line should be your domain name, this is used to construct the ‘domainname\user’ text used in the script. The $root variable is the root folder containing the folders to have permissions applied.

It’s quick and dirty – only used for a one off & there’s no error checking so be careful before you use it!

Rob

DCDiag functionality

Rob Broughall — Wed, 23 Mar 2011 07:49:54 +0000

DCDiag is one of those tools which is generally only used when things are going wrong, it can be very handy in finding directory services issues (which can manifest themselves in all kinds of ways….) Ned Pyle on the Directory Services team blog has written a brilliant post on this tool & what the various switches are actually doing for you, well worth a read (hopefully before you have to use it in anger): http://blogs.technet.com/b/askds/archive/2011/03/22/what-does-dcdiag-actually-do.aspx

Rob

RSS, Chimney & NetDMA

Rob Broughall — Tue, 22 Mar 2011 07:47:32 +0000

Hi,

I was recently on a call with some Exchange peers & we were fortunate enough to have a guest appearance from Tod Edwards from the Windows Server team at Microsoft. He attended to provide some background & recommendations to making the above technologies work successfully with Windows Server and why they should be enabled where possible. As this information is in the public domain & helps improve everyone’s experience I have reproduced it here.

Background

RSS – Receive Side Scaling, this allows a server to spread network interrupt traffic over more than 1 CPU, significant benefits have been seen with this on 1Gb+ network interfaces

TCP Chimney – Allows the offloading of TCP/IP processing to the network card, both Intel and Broadcom have NICs in the market which support this, the benefits with this feature are less pronounced at 1Gb connections but significant at 10Gb connections (think iSCSI storage connections)

Chimney is incompatible with some features in Windows (firewall, etc.), & if they are enabled Chimney will not offload any connection. In W2008 R2, the Windows Firewall is compatible with Chimney, which was a change from previous OS.

TCP Chimney Offload is not the same thing as Checksum Offload, Large Send Offload, etc. Those offloads have been around for since W2003 & are generally problem free.

RSS & Chimney both require the above basic checksum offloads to function, so disabling any of them (in NIC properties) will automatically keep RSS and Chimney from being used.

Compatibility issues

As alluded to above, these technologies work really well with 2008r2 out of the box, on older operating systems (2003) you’re probably already familiar with needing to disable these to resolve issues, here are recommendations as to how things should be configured for the various Microsoft Server OSs in the market at this time:

W2003 SP2: RSS, Chimney & NetDMA are known to be problematic. Customers should disable these manually or use KB:948496. If you really need the features, install SNP roll-up (KB:912222) for W2003 and re-enable features.

W2008 RTM: RSS is on by default but Chimney is off. RSS had some issues that customers hit after installing W2008, most were resolved in SP2, & remaining were solved in KB:979614 (which brings RSS/Chimney to W2008 R2 level).

W2008 R2: RSS is on by default & Chimney is in ‘Automatic’ mode, which means the TCP connection being offloaded has to be 10Gb speed, less than 20ms latency between the 2 end points, & transmitted at least 130k. See page 6-7 of ‘W2008 R2 Networking Deployment Guide: Deploying High-Speed Networking Features‘

Win2008 R2 SP1 does not contain any fixes related to Chimney, and only has 1 fix for RSS that fixes a bug where RSS only uses 1 CPU when you have over 32 processors, KB:977977

If you’re seeing issues on modern operating systems which are resolved by disabling the above features ensure you’re systems are using the most recent NIC drivers, filters (teaming, AV, firewall etc..) & BIOS – whilst the market has matured there are still issues resolved with updated vendor drivers. It is important to work through these issues & use the functionality, in the Exchange world customers have achieved higher throughputs & got more value out of their hardware by getting these features turned back on.

Rob