Most installations of Windows 7 include a tiny 100 MB partition named 'System Reserved'.  This is also known as the MSR or “Microsoft System Reserved' Partition. For brevity I'll refer to this partition as  MSR throughout the rest of this article.

Note: Some OEM installations may name this partition 'System' or even 'Recovery'. In all cases it will be the 'Active' partition on the same disk as drive 'C'.

Have I got an an MSR partition?

Some OEM installs of Windows 7 don't include the MSR partition. To check whether you have this partition start up Macrium Reflect and look for a 100MB partition on the system disk named 'System Reserved'.

Note: If drive 'C' is your 'Active' partition you just need to backup and restore 'C' for full system recovery.

What does the MSR partition do?

The MSR partition handles the second stage of the boot process after the Master Boot Record (MBR). The MBR resides on the first sector of the disk and is loaded at system start-up, after loading control is passed to the partition boot sector code of the active partition, this is the MSR partition if it exists, if not it will be your 'C' drive. The MSR contains a  '\boot' directory that contains the Boot Configuration Data (BCD). The BCD controls the  next stage of the boot process and loads the Operating System  from drive C:.

The MSR partition is always the 'Active' partition on your system disk and should be restored as the 'Active ' partition. The contents of this partition doesn't change and, by default, isn't assigned a drive letter by Windows so you can't modify it.

Do I need to image it?

Imaging the MSR partition is essential to recover your system from a disk crash or to move your system to a new disk. However, if you just need to recover your system to an earlier date then restoring the MSR partition isn't necessary, you just need to restore drive C.

It's necessary to restore your Windows 7 partitions to the same locations for the BCD to still be able to reference them when booting. If you are restoring to a new or unformatted disk then first restore the MSR as the 'Active' partition followed by drive C as 'Primary'. An easier solution is to use DiskRestore to restore both partitions at the same time. DiskRestore is available with the Windows PE rescue CD and can be run from BartPE if you are running the free edition of Macrium Reflect. For more information on DiskRestore please see here: http://www.macrium.com/KB/KnowledgebaseArticle50004.aspx 

Summary

• You should create at least one image of the MSR partition if it exists on your system. However, as the partition is only 100MB it is only a small overhead to image it along side all images of your 'C' drive.
   
• If you want to restore your system to an earlier point then you just need to restore drive 'C' (as 'Primary not 'Active'), it isn't necessary to restore the MSR partition but it won't hurt.
   
• If you are restoring your system to an empty or unformatted disk then you should first restore the MSR partition as the 'Active' partition, then restore drive 'C' as Primary.