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VSS System Components

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Overview

 
The WholesaleBackup software client, since it’s first version, has utilized the Microsoft Volume Shadow Copy Service (VSS) framework for backing up open files in what Microsoft terms as a “crash consistent state” (i.e. backups of all open files will be at a specific moment in time consistent with what has been written to disk at that time, as if the computer crashed at that point).
 
The client software supports the VSS Component API for backing up, in a safe integral state, collections of files and folders associated with some application Component, such as Microsoft Exchange and NTDS (Active Directory). 
 
The implementation of every VSS Component Writer was done by the application vendor itself (for example Microsoft, Oracle, VMware, etc.), thus the actual file backup process provided by a VSS Component is implemented by the actual author of the associated application.  Backup utilities that support Microsoft’s VSS interface are called Readers and are abstracted from details which the application vendor’s specific backup procedure requires, thus allowing a well-written Reader to backup dozens of different applications using a single method.

The WholesaleBackup software client is a VSS Reader that makes standardized calls to the VSS API, and thus WholesaleBackup can backup any application, including some operating system functions supported by Microsoft, which have implemented a VSS Writer for their files.  WholesaleBackup’s VSS Reader backs up files in either “full mode” or “copy mode” , and then WholesaleBackup will either use it’s own full or differential methods to transmit those files to the backup servers using the method you have specified within WholesaleBackup (the default is differential, a.k.a. delta block, to minimize the client’s Internet bandwidth).

Example applications and Operating System components supported
 
Depending on what applications are installed and which operating system a given computer is running, the list of VSS System Components selectable to backup in the WholesaleBackup software client will vary.
 
Some of the applications with VSS file Writers include
  • Microsoft Exchange Server
  • Microsoft Hyper-V
  • Microsoft IIS
  • Microsoft SQL Server 
  • Oracle
  • VMware
Some of the operating system components with VSS file Writers include
  • COM+ REGDB Writer
  • FRS Writer
  • NTDS (Active Directory)
  • Performance Counters
  • Registry
  • System (State) 
  • Task Scheduler
  • WMI Writer
 
Backing up specific files vs. all files for a System Component
 
Whether or not you select an entire VSS Component to backup, the WholesaleBackup client will activate the Component’s Writer, so for example, if you select a single SQL Server .MDB file or an Exchange .EDB file, the backup of that file will occur using the corresponding VSS Component if the file is specified as being served by the Component.  What this means is that whereas formerly, selecting an .MDB file would ensure it was in a “crash consistent state” but all its data might not be written to disk (and thus the backup), now the file would be backed up via Microsoft’s “SQLServer Writer” which means it is in a known restorable state.

A word of caution is required here, whenever you select specific files and folders to backup you should be absolutely certain you are selecting all of the files you will need to restore and that you are using all the protocol and methods the application vendor specifies for those files.
 
It is important to keep in mind that application vendors have written the backup utilities for all VSS components, not WholesaleBackup.  WholesaleBackup follows the standardized API implemented by Microsoft VSS, in performing file “full copy” backups, and the application vendor has actually implemented the corresponding file backup for their application.  Some application vendors may require additional actions, including backing up of files they do not specify in their VSS Writer implementation, which must be taken to completely backup their application or system component (as an example, this can occur when the Microsoft VSS programming interface is not sufficiently flexible to specify a complete backup of the vendors application).  So, with one exception, the WholesaleBackup software client is unaware of any extra non-VSS requirements, and thus it is the user’s responsibility to ensure that all appropriate files are selected for backup and any additional actions are taken.  The one exception is that, due to popular demand, the WholesaleBackup client has extended its VSS Reader with extensions for Microsoft Exchange to automatically run the Microsoft eseutil checksum utility to perform checksums on Exchange .LOG and .EDB backup files and will log the results to the backup log when the Exchange Component is selected.  As a result of this extension, WholesaleBackup is complying with one requirement for Microsoft to provide you with technical support, if you should need it, in restoring Exchange when it is backed up using WholesaleBackup (more information can be found here: http://support.microsoft.com/kb/822896).
 
Requirements
 
Please note that the actual “Volume Shadow Copy Service” must be installed on the operating system (it is by default) and runnable.  In some cases you may need to install or configure additional services for a specific application, a few examples are:
Microsoft Exchange on SBS 2003 – http://support.microsoft.com/kb/838183
 
Please note that on Windows Server 2003 the EXCHSRVR\BIN folder must be added to the system path by following the procedure at http://technet.microsoft.com/en-us/library/aa997841(v=exchg.65).aspx, otherwise you will see errors such as the following when the client software attempts to run eseutil:
Error, Eseutil checksum failed with Microsoft Eseutil return error code -1
       on Microsoft Exchange file [\\?\C:\Program Files\Exchsrvr\mdbdata\E00.log].
Info,  The source of this problem may be:
Info,  Eseutil error output follows: {'eseutil' is not recognized as an internal
       or external command, operable program or batch file.}
 
Restoring Applications (vs. Restoring Files) – Important Note
 
Nearly all application vendors who have written VSS Writers also specify steps, which are unique to their application, which must be taken to restore files into their application (or the operating system itself).  As a result, in WholesaleBackup, when restoring files associated with VSS Components, you will need to first restore these files to a new location using the WholesaleBackup software client and then utilize the documentation and utilities of the application or operating system to restore your applications, so at present the WholesaleBackup software client does not perform VSS restores.
 
As examples of unique restoration steps, for Microsoft Exchange 2010 visit http://technet.microsoft.com/en-us/library/dd876874.aspx for how to restore the entire Exchange Store and http://support.microsoft.com/kb/823176 for how to use Microsoft’s utilities to restore a specific mailbox for Exchange 2003.
 
Copy Mode vs. Full Mode for VSS Backups (flushing Exchange logs)
 
One can specify either “Copy Mode” or “Full Mode” for backing up files through VSS components.  This is done in the INI file with the VSS keyword and it can be done interactively in the User Interface on the "Expert" tab when launched in expert mode.   The default (VSS 1) will backup all files in “Copy” mode (see Microsoft’s documentation for VSS_BT_COPY), but you can backup files in “Full Mode (VSS_BT_FULL) which will reset the archive flag on each file and possibly take other action, such as truncating the Microsoft Exchange logs.  Please refer to the VSS Component documentation for your particular application to understand how the vendor’s VSS Writer will behave in Copy and Full mode.
 
You can specify the mode either via the INI file or through the User Interface on the “Expert”  tab when the GUI was launched in  expert mode as follows:
Copy_VSS_BT_COPY.png
Copies of files (a note about Exchange Reader implementation)
 
With one exception, the WholesaleBackup software client implementation as a VSS Reader does not make any additional copies of files beyond what the client software ordinarily does in making an encrypted/compressed copy of a file to checksum and backup.  The one exception is that, in order to run eseutil on Microsoft Exchange files, the WholesaleBackup software client has to call the Exchange Writer to backup the file to a holding area, and then perform the eseutil checksum on that copy, before encrypting/compressing the file to backup.   Once the file is encrypted and backed up, the extra copy of the file is securely deleted from the temporary working space.  
 
IMPORTANT NOTE Regarding Restoring Operating System (VSS) Components
 
Microsoft provides several built-in (“in-box”) System Component (VSS) Writers for Active Directory, Registry, System State, etc.  A partial list can be found at http://msdn.microsoft.com/en-us/library/windows/desktop/bb968827(v=vs.85).aspx.  Unfortunately, Microsoft does not provide developer or IT professional technical support for implementing online system state restores on any version of Microsoft Windows for the System (State) Writer.  Since Microsoft does not provide you or us with technical support, we are unable to provide you with technical support for restoring files backed up using Microsoft’s “System Writer”, and thus it is intended for experts only and unsupported by Divinsa LLC.
 
General Offline Restoration Process for Microsoft’s Operating System Components
 
In general, an offline restoration process for most of Microsoft’s “in-box” System Components can be accomplished using steps such as these:
  1. Restore all of the System Component’s files to a “New Location” using our software client
  2. Boot Windows into an “offline mode”, e.g. “Recovery Console” for pre-Windows 2008 and “Windows Recovery Environment” for Windows Server 2008 and newer.
  3. Copy the files you restored in step 1 to their original location
  4. Reboot your server into Normal mode
You may wish to pre-emptively install the appropriate Microsoft recovery tools on your server now, as a boot time option, rather than having to boot from media such as CD or DVD later.  To install Microsoft’s “Recovery Console” as a bootup option, please visit: http://support.microsoft.com/kb/326215, and to install Microsoft’s “Windows Recovery Environment” as a bootup option, please visit: http://blogs.msdn.com/b/winre/archive/2007/01/12/how-to-install-winre-on-the-hard-disk.aspx. 
 
Some Microsoft Components Provide Online or Near-Line Restoration
 
Some in-box Microsoft System Components can be installed in near-line ways, such as restoring Active Directory while in DSRM (“Directory Services Restore Mode”) for Windows Server 2003 (F8 during boot) or by stopping Active Directory on Windows Server 2008 and newer.  Please refer to http://msdn.microsoft.com/en-us/library/windows/desktop/aa384675(v=vs.85).aspx and http://en.wikipedia.org/wiki/Directory_Services_Restore_Mode for more information for Active Directory in particular, and your Microsoft documentation for other System Components.
 
A Resource for Restoring Microsoft’s Operating System Components
 
A good resource for additional information is Microsoft’s “MSDN Community Center” at http://msdn.microsoft.com/en-us/aa497440.aspx.  
 
Restoring a Microsoft SQL Server .MDF and _1.LDF
 
Restoring Microsoft SQL Server databases from MDF/LDF files is straightforward using Microsoft SQL Server Studio Management Express.  The procedure is simply one of replacement and attachment:
  1. Restore the .MDF and _1.LDF files to a new location using our software client.
  2. In Microsoft SQL Server Studio Management Express right-click on the database you will be restoring in the left tree-view, make note of the location of its files (it may be something like C:\Program Files (x86)\Microsoft SQL Server\MSSQL.1\MSSQL\Data), and pick Detach.
  3. Copy the .MDF and _1.LDF file from step 1 to the location of the files you detached in the previous step and be sure the permissions on the two resultant files are the same as the files you overwrote (else you will get an error in the next step).
  4. In Microsoft SQL Server Management Studio Express Right-click on Databases in left tree-view and pick Attach and then choose the .MDF file you replaced in the previous step.
 
Selecting System Components and associated files in the GUI
 
Selecting System VSS Components to backup and restore is very straightforward in the user interface.  The following screen capture shows the process for selecting components to backup:
vss_file_restore_gui.png
Expanding a VSS writer will show the files that will be backed up when selected.
Expanding_a_VSS_writer_will_show_the_files.png

Selection file syntax for System Components 
 
The Backup->Selections tab in the GUI is simply an editor for the .SEL selections file which is what is used by the engine to know what files and folders have been selected and excluded.  A detailed description of the syntax and it’s power, including using filters and expressions, can be found here.

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