Here is a good command to use if you want to find out the size of all your mailbox databases in Exchange 2010:
Get-MailboxDatabase –Status | fl name, databasesize
It should output something similar to this:
You can simply copy and paste the above command into an Exchange 2010 PowerShell window and run. Hope this helps.
Paul
We came across an issue recently where we had an issue with our Hyper-V 2008 R2 server. The BOOTMGR file went missing on a reboot , all this was repaired by running Bootrec commands.
After the above the Hyper-V server would boot up however none of the VM’s would start and came up with the following error
“The virtual machine could not be started because the hypervisor is not running. The following actions may help you resolve the problem:
1) Verify that the processor of the physical computer has a supported version of hardware-assisted virtualization.
2) Verify that hardware-assisted virtualization and hardware-assisted data execution protection are enabled in the BIOS of the physical computer. (If you edit the BIOS to enable either setting, you must turn off the power to the physical computer and then turn it back on. Resetting the physical computer is not sufficient.)
3) If you have made changes to the Boot Configuration Data store, review these changes to ensure that the hypervisor is configured to launch automatically.”
The issue was that when we recreated the BCD store in did not set the Hypervisor to launch automatically.
We resolved this by running the following command “bcdedit /set hypervisorlaunchtype auto” after a reboot all worked fine 
We had an issue recently with one of our Windows 2008 R2 servers , where after reboot the server did not come back up and showed the following error “BOOTMGR is Missing”
I fixed the by recreating the Boot Configuration Data Store.
After this all should be up and Running 
A customer recently had an issue where the Microsoft Exchange Information Service and the Exchange Transport service would fail to start after a reboot. While investigating this issue, we noticed the following events in the Application log:
Event Type: Error
Event Source: Service Control Manager
Event Category: None
Event ID: 7022
Description:
The FSCController service hung on starting.
Event Type: Error
Event Source: Service Control Manager
Event Category: None
Event ID: 7001
Description:
The FSEIMC service depends on the FSCController service which failed to start because of the following error:
After starting, the service hung in a start-pending state.
Event Type: Error
Event Source: Service Control Manager
Event Category: None
Event ID: 7001
Description:
The Microsoft Exchange Transport service depends on the FSEIMC service which failed to start because of the following error:
The dependency service or group failed to start.
Solution:
Ensure Service Pack 2 is installed for Forefront Security for Exchange Server
We came across an issue recently on a Exchange 2007 server in regards to services not automatically started when the server was rebooted.
After reviewing the event log post start up i found the following events.
“Event Type: Error
Event Source: Service Control Manager
Event Category: None
Event ID: 7022
Description:
The FSCController service hung on starting
Event Type: Error
Event Source: Service Control Manager
Event Category: None
Event ID: 7001
Description:
The FSEIMC service depends on the FSCController service which failed to start because of the following error:
After starting, the service hung in a start-pending state.
Event Type: Error
Event Source: Service Control Manager
Event Category: None
Event ID: 7001
Description:
The Microsoft Exchange Transport service depends on the FSEIMC service which failed to start because of the following error:
The dependency service or group failed to start.
Event Type: Error
Event Source: Service Control Manager
Event Category: None
Event ID: 7001
Description:
The Microsoft Exchange Information Store service depends on the FSCController service which failed to start because of the following error:
After starting, the service hung in a start-pending state.”
The cause of this issue was down to Forefront Security for Exchange , installing Forefront Security for Exchange SP2 fixed the issue 
Microsoft KB Documenting the Issue“http://support.microsoft.com/kb/961728”
Here’s a few quick PowerShell commands that will allow you to Disable or Enable a Service and Start or Stop a particular service.
To Enable a particular service run the following command. (Please Edit ServiceName to the desired service)
Set-Service ServiceName -StartupType Automatic
To Disable a particular service run the following command.
Set-Service ServiceName -StartupType Disabled
To Stop a particular service run the following command.
Stop-Service ServiceName
To Start a particular service run the following command.
Start-Service ServiceName
You can also combine the commands in a ps1 file , for example if you want to Disable and Stop a Service you would run the following.
“Set-Service ServiceName -StartupType Disabled
Stop-Service ServiceName”
When using Forefront Protection for Exchange, a legitimate sender gets the following bounce back when trying to e-mail you:
“550 5.7.1 :127.0.0.3:Client host … blocked using 88.blocklist.zap; Mail from IP banned. To request removal from this list please forward this message to delist.forefront@messaging.microsoft.com”
If you are sure that the sender is legitimate and trusted, mail from the senders domain can be allowed by completing the followings solution.
Solution:
Add the IP address of the remote domain to the “IP Allow List” on your Edge servers. (This IP can be found in the NDR or by contacting the remote party):
You receive the following error when installing Cumulative Update 2 for System Centre Service Manager SP1:
“An error occurred while executing a custom action:_ExecuteSqlScripts”
Solution:
Add the service account to the sysadmin group in SQL
Just a quick command here to logoff remote machines via PowerShell
“(gwmi win32_operatingsystem -ComputerName ComputerName -cred (get-credential)).Win32Shutdown(4)”
This will log every user off the machine specified above.
This is a quick command to add every mailbox in a specific database to a Specific Retention Policy,
This will now have added every mailbox from the mailbox database you specified to the desired retention policy 
