Post by J. P. Gilliver (John)
Prompted by the thread where we're trying to help "fake" with his "dark"
I have a 100 MB (MB, not GB) hidden partition, before my C: partition
(which is 100 GB).
o "System Reserved" [where other partitions are "(C:)" and "data (D:)"
o "100 MB NTFS"
o "Healthy (System, Active, Primary Partition)"
o 62 MB (so 62%) free, i. e. there's only 38 MB on it.
I'm unlikely to use it, as my backup policy is to image C: (and this
hidden one), but I keep it there as it's so small and _might_ be useful.
But I'm wondering what _is_ there: it obviously isn't anywhere near a
copy of Windows 7 waiting to be restored in emergency. But 38 MB, though
tiny compared to Windows (which I think is at least about 20 to 30 GB
unpacked), is to me a lot more than just a boot sector, boot manager,
and so on. So what _is_ in there? What _does_ happen if it is ever
The default install of Windows 7 will be to create 2 partitions. To
provide for recovery options (in case a partition gets corrupted and to
avoid requiring Windows to load), a 100 MB recovery partition gets
created. That will contain the boot sector (first sector of a partition
that the BIOS' boot loader will load into memory and to which control
gets passed), the boot loader (for wherever is the Windows kernel), boot
manager, BCD database (for boot manager), and recovery options. By
having the recovery options in a different partition, they can work on a
non-working instance of Windows in the other partition.
That is *if* there do not already exist any partitions on the target
drive. The get around Windows 7 using 2 partitions, you have to first
[format the drive and] create a partition on the drive, the one where
you intend to install all of Windows 7 in just one partition. If you
use one partition, the boot sector, boot loader/manager/BCD, kernel and
rest of Windows gets loaded into that one partition. If there is
already a partition on the drive, the Windows installer won't change the
partition layout. You could create a partition for some other user and
Windows would use the rest of the drive to create one partition for
itself, or you could point its installer at that partition to get it
installed in that partition.
Microsoft names these partitions unintuitively. The system partition
(small one) is where are the boot files. The boot partition (the big
one) is where are the system files: kernel, rest of OS, apps, and data.
The system and boot partitions can be separate partitions or they can be
the same partition. The point of having a separate partition for the
system is to have recovery options *outside* the partition of the OS
you're trying to repair. While that provides convenience to the typical
user in having the recovery options available on the drive inside the
computer, you can use one partition (that you've already created before
installing Windows) and then create the Windows rescue CD to give you
the recovery options. Another choice is to install another OS into the
BCD for recovery options. That doesn't create a new partition but
instead deposits a .dat file which is an image of an OS environment. It
will get loaded as an imaged OS; however, its .dat file is in the file
system of the OS you are trying to repair. This is also how many backup
programs add a startup option: they create a .pim (Windows PE image with
their program added) and add an entry in BCD to load the .pim image
file, if selected on boot. Just like the recovery image in the .dat
file, a .pim file is in the file system of the OS you are trying to
restore, so make sure to also create a rescue CD for the backup program
to use if the file system gets corrupted or the entire partition
disappears (some malware works by deleting the partition records [but
the partitions are still left behind to recover] or they change the
indexing in the records to offset the partition record but doesn't match
where is the actual partition).
Some multi-boot managers can work with their code solely contained
within the boot sector (e.g., GAG). Some require their own partition:
they still use the boot sector but the rest of the program is saved in a
small partition. Some are stupid in putting themselves within the same
partition as the OS (so if that file system gets corrupt then the multi-
boot manager becomes useless and you lose access to all OSes in the
other partitions. Microsoft decided to emulate the 2nd approach with
their dual-boot manager (don't ask me why Microsoft used "dual" instead
of "multi" since their boot manager with its BCD can load multiple
OSes). The process actually loads the Windows boot loader and boot
manager as the multi-boot manager to then presents what OSes are
available in BCD (boot configuration data) database - which is a binary
database (instead of the old boot.ini text file) and why you have to use
bcdedit to alter its content (like you use regedit to alter the contents
of the registry which is also a binary database).
You could assign a drive letter to the 100 MB partition if you want to
see what is on it. Of course, that leaves it open to malware that hunts
around for drives (by letter designation). I've never bothered to
research if the system and boot partitions (after putting them in
separate partitions during installation) can be merged into one
partitions. For one thing, the entries in the BCD would end up pointing
to partitions that no longer exist or are invalid pointers because
partition layout has changed in its indexing.
You never mentioned whether you built this computer or if you bought a
pre-built. The pre-builts will use the 2-partition layout, and may even
have a 3rd partition where the factory image or a default installer gets
saved as another recovery option made available by the pre-built maker.