You can't make your Exchange 2010 Jetstress tests to pass

If you're testing your disk subsystem for Exchange 2010 with Jetstress and you're unable to make it "green" pass because database read latency is higher than 20 msec than it's time for reducing number of threads and for fine tuning. But, if you reduce number of threads than you will lose number of IOPS.
For example: with 2 threads you can't achieve required number of IOPS and with 3 threads you're achieving number of IOPS but database read latencies are higher than 20 msecs, in that case you can use "SluggishSessions" parameter. You can find this parameter in JetstressConfig.xml file. By default this parameter is set to 1, you can start increasing this number by 1, which will make Jetstress to add pause between tasks. With increasing "SluggishSessions" parameter you will lose IOPS.

For example : with thread count 3 and SluggishSession 2, I was able to achieve required number of IOPS but database read latencies were still higher than 20msec:

So with increasing number of SluggishSessions to 3 I was loosing IOPS but database read latencies were lower than 20 msec:

For more on threads and "SlugishSessions" check the following Technet article : http://technet.microsoft.com/en-us/library/ff459238.aspx

Your VM running on Hyper V is not in sync (time)

I have experienced something strange on Hyper V cluster based on Windows Server 2008 R2 SP1 Enterprise and VM guest with same OS but Standard edition, with time synchronization enabled but VM was still out of sync.

I have checked that Windows time service was running and queried the source for synchronization and it was free running system clock !

After restarting the windows time service, the VM started to sync with local CMOS clock instead of synchronizing with host (parent partition).

I'm guessing that VM was not reading the setting for the time synchronization from the VM configuration, so I have disabled the setting and re enabled and restarted the windows time service, and finally within few seconds the VM was synchronizing the time with host :

One more thing : if the server is Windows 2008 R2 and the machine is not domain joined the windows time service will stop automatically. On reboot you can see the following event :

This behaviour is by default and you can find more info on translated Japanese kb :
http://translate.google.com/translate?hl=en&sl=ja&u=http://support.microsoft.com/kb/2385818/ja

Object "computername" contains other objects

If you try to delete computer object in AD, you might receive warning message that Object <computername> contains other objects. To see what that computer object contains select in View menu "Users,Contacts,Groups and Computers as containers" in Active Directory Users and Computers Console and you will be able to see what that computer object contains.

In most cases it will be a printer, if the computer object is client workstation.

"Internet Explorer has modified this page to help prevent coss-site scripting."

Internet explorer 9 includes cross-site scripting (XSS) filter which is enabled by default http://windows.microsoft.com/en-GB/internet-explorer/products/ie-9/features/cross-site-scripting-filter . In my case IE 9 was pushed via WSUS, and there were couple of older web applications still running, that IE9 was preventing from running properly thanks to the enabled XSS filter.
If you trust the application or it is running on intranet, and from some reason IE 9 is not applying local intranet zone settings, just add the link manually to the local intranet zone (local intranet zone has by default XSS filter disabled).

You can't deploy OS on client in SCCM 2007 SP2

If you try to install OS to the same client within one hour from the previous deployment, the machine will fail to boot into PXE. To fix this change the (HKLM\Software\Microsoft\SMS\PXE\CacheExpire value to for example 120 (2 minutes), 0 is presumed 60 minutes. For more info please check http://support.microsoft.com/kb/2019640 .