There are three specific keys that control behavior of System Restore Utility. It has many values that
can be altered and also have some that should not be altered under any circumstances. Microsoft
Article The Registry Keys and Values for the System Restore Utility (Q295659) explains it all in detail
this but in brief following three keys are important.
1. HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Sr
2. HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Srservice
3. HKEY_LOCAL_MACHINE\Software\Microsoft\WindowsNT\CurrentVersion\SystemRestore
Only some sub-keys of third key can be modified without harming your computer. Read the Microsoft
Article to know what can not be modified.Following keys can be modified (copied from Microsoft
Article):
CompressionBurst
This value, listed in seconds, specifies the idle time compression: The amount of time to compress data
after the computer reaches its idle time. A service can compress data for the amount of time that is
specified in this value, and then stop. Then, at the next idle time compression, the computer can repeat
the process.
DiskPercent
This value relates to the percentage of disk space that System Restore uses for its data store. The
default value is 12 percent. The data store size is always calculated as "max(12 percent, DSMax),"
regardless of the size of the hard disk. The maximum (max) size is what is specified in DSMax. For
hard disk sizes that are less than 4 gigabytes (GB) in size, 12 percent is less than 400 megabytes (MB),
so "max(12 percent, DSMax) equals 400 MB." For hard disk sizes that are greater than 4 GB, 12
percent is greater than 400 MB, so "max(12 percent, DSMax) equals 12 percent." This data store size is
not a reserved disk space, and the data store size is used only on demand.
DSMax
This value specifies the maximum size for the System Restore data store. The default size of the data
store is 400 MB. The data store size is always calculated as "max(12 percent, DSMax)," regardless of
the size of the hard disk. The maximum (max) size is what is specified in DSMax. For hard disk sizes
that are less than 4 GB, 12 percent is less than 400 MB, so "max(12 percent, DSMax) equals 400 MB."
For hard disk sizes that are greater than 4 GB, 12 percent is greater than 400 MB, so "max(12 percent,
DSMax) equals 12 percent." This data store size is not a reserved disk space, and the data store size is
used only on demand.
DSMin
This value relates to the minimum amount of free disk space that System Restore needs so that it can
function during the installation process. Also, this value relates to the minimum amount of free disk
space that is needed for System Restore to reactivate and to resume the creation of restore points after
System Restore has been disabled because of low disk space.
RestoreStatus
This value specifies if the last restore operation failed (0), succeeded (1), or had been interrupted (2).
RPGlobalInterval
This value specifies, in seconds, the amount of time that System Restore waits before it creates the
automatic computer check points for elapsed time. The default value is 24 hours.
RPLifeInterval
This value specifies, in seconds, the restore points Time to Live (TTL). When a restore point reaches
this time and it is still on the system, it gets deleted. The default value is (7776000), which will be 90
days.
RPSessionInterval
This value specifies, in seconds, the amount of time that System Restore waits before it creates the
automatic computer check points for session time (the amount of time that the computer has been on).
The default value is zero (0), which means that this feature is turned off.
ThawInterval
This value specifies, in seconds, the amount of time that System Restore waits before it activates itself
from a disabled state (after the conditions for this process to occur have been met). If you start the
System Restore user interface, System Restore is activated immediately.
