Unable to create snapshots on Windows guest operating systems

Creating a snapshot (including the memory state) of a virtual machine on Windows fails
You see the error:
Cannot create a quiesced snapshot because the create snapshot operation exceeded the time limit for holding off I/O in the frozen virtual machine
The VMware Snapshot Provider service does not get installed when installing VMware Tools
Uninstalling and re-installing VMware Tools does not resolve this issue
This issue can occur on Windows 2003 and 2008 operating systems if the VMware Snapshot Provider does not get installed.
To work around this issue manually register the VMware Snapshot Provider:
Click Start > Run, type cmd, and click OK.
Enter these commands, in sequence:
regsvr32 "C:\Program Files\VMware\VMware Tools\Drivers\vss\VCBRequestor.dll"
regsvr32 "C:\Program Files\VMware\VMware Tools\Drivers\vss\VCBSnapshotProvider.dll"
"C:\Program Files\VMware\VMware Tools\COMREG.EXE" -register "C:\Program Files\VMware\VMware Tools\Drivers\vss\VCBSnapshotProvider.dll" "VMware Snapshot Provider" "vmvss" "VMware Snapshot Provider"
For more information read this article from VMware KB.

How to restore the default vCenter Server alarms

To restore the default vCenter Server alarms, you must remove all existing alarm definitions in vCenter Server and then set the value of alarm.version to 0.
To delete all the existing alarm definitions in the vCenter Server:

•     Log in to the vCenter Server using the vSphere Client.
•     Click the Hosts and Clusters view.
•     Click the Alarms tab.
•     Click Definitions.
•     Note: All custom alarms must be manually recreated after they are removed. Ensure to note the custom alarms before removing.
•     Select all alarms, right-click, and  click Remove.

To restore the default vCenter Server alarms, change the alarm version in vCenter Server:

•     Connect to vCenter Server using the vSphere Client.
•     Click Administration > vCenter Server Settings.
•     Click Advanced Settings.
•     Set alarm.version to 0.
•     Set alarms.upgraded to false
•     Restart the VMware VirtualCenter Server service.

For more information take a look at this VMware article.

How to reset domain admin password on a Windows Server 2008

1. Boot onto DVD of Windows Server 2008
2. Choose “Repair your computer”
3. Launch cmd
4. Go to c:\windows\system32
5. Rename Utilman.exe to Utilman.exe.bak
6. Copy cmd.exe to Utilman.exe
7. Reboot on Windows
8. Do the keyboard shortcut Windows + U when on the logon screen
9. net user administrator Newpass123 inside the cmd
10. log on with the domain admin account and this new pass
11. change the password to remember it if needed
12. Reboot on the DVD to put back the original Utilman.exe

For more info take a look at this link

Setting up Serial Logging for Linux/UNIX virtual machines

To enable Serial Logging:
Right-click the virtual machine or virtual appliance and click Edit Settings.
Click the Hardware tab and then click Add.
Select Serial Port and click Next.
Select Output to file and click Next.
Click Browse and navigate to the virtual machine for which you want to add a serial port.
In File Name, type SerialOutput and click OK.
Under Device Status, select Connect at power on and click Next > Finish.
Click the Options tab.
Click Boot Options and enter 10,000 in Power On Boot Delay.
Click OK to commit the changes.
Power on the virtual machine. The virtual machine waits for 10 seconds before it begins to load the operating system.
After the operating system loads (a blue background loads), you see this line on top of the screen:
Press any key to enter the Boot menu
Press the Space Bar to enter into the GNU GRUB.
Select the operating system, such as CentOS (2.6.18-164.9.1.el5), and press e to modify the grub options.
Use the down arrow key to select the line:
kernel /vmlinuz-2.6.78-164.9.1.el5 ro root=LABEL=10 console
Press e to append this line:
console=ttys0,115200 console=tty0
Press Enter to commit the changes.
Press b to boot into the grub.
After a boot failure, power on the virtual machine, log in to the host that manages the virtual machine, and navigate to the home directory. You should see a file named SerialOutput, which is the new Serial Logging log. 
For more info read the following article from VMware

How to add a DSRM startup option in Windows Server 2008 R2

From this blog post we should open an administrator command prompt and enter these lines:
bcdedit /copy {current} /d "Directory Services Restore Mode"
bcdedit /set {GUID} safeboot dsrepair
bcdedit /timeout 10
where {GUID} is the result of the first command.

How to find the exact version of my Exchange 2010

From a powershell console enter this command:
Get-Exchangeserver -Identity
If you want to know the exact version then enter this command:
gcm exsetup |%{$_.Fileversioninfo}
For more info take a look at this article from Technet.

How to update ESXi 5 using esxcli

Please read the following article from VMware.