Shrinking Extended Partition in Win7

[DiracDeBroglie]

Under Win7, on an external 2TB USB3 MBR formatted drive.

In Disk Management extending and shrinking a logical volume beyond the extended partition encapsulation does not work. However, with diskpart.exe extending a logical volume beyond its extended partition works just fine; the end of the extended partition just gets "pushed" away deeper into the unallocated area outside the extended partition.

If then the last (most right-side) logical volume in the extended partition gets shrunk, the right side of the extended partition does not move; some free space at the end and within the extended partition is the result.

I've tried to move the right-side end of the extended partition towards the left so to add that (extended) free space to the unallocated area where I want to use it for the creation of a primary partition; it simply does not work!!

Why is that? What is the technical reason why diskpart can move the end of an extended partition to the right but NOT to the left, although there is plenty of free space adjacent left?? Why can diskpart calculated a new end position in case of expanding the extended partition but not when it needs to shrink the extended partition?

Johan

[Ponch]

Maybe MS has decided it was not useful.

I't be easier to follow if you stick to the 3 operations "move", "extend" and "shrink" rather than using poetry like "move the right side to the left" or "the end of the partition gets pushed away deeper".

I can't make tests, but I see that in diskpart, (option 2 point 5) selecting your extended partition, you could type "shrink querymax" and get the possible amount that can get taken off the partition. Does it report anything ?

[DiracDeBroglie]

Shrink Querymax did not help. It simply did not work probably because I selected the extended *partition*, and that is not a volume.

As far as I know any direct action of Diskpart is on volumes, not on partitions.

With List Partition I can see all my primary partititons, and the one extended partition too with all its logical partitions.

Shrink and Extend work on all primary partitions, probably because Diskpart sees those are also volumes. (I've not tried to Shrink or Extend a primary partition without any filesystem it.)

I find it a very strange that an extended partition can get extended if need be by the last logical volume it contains, but shrinking an extended partition does not work.

I've tried Shrink and Extend also on an *empty* extended volume, meaning there are no logical volumes in it, only 100GB of free space; nonetheless, it still does not work, the extended partition is untouchable for any direct action in Diskpart.

Pretty fustrating that an extended partition cannot be shrunk if one needs to free up extra space for an additional primary partition.

The end sector of the extended partition must be stored somewhere in the EPBR, or in the MBR, or maybe in both (I don't know for sure).

Are there any (free and userfriendly) system utilities that act on the EPBR or the MBR with which the user could shift the end sector of the extended partition?

I've tried Partition Wizard, the free edition as well as the boot CD version, but that was a total mess; the beginnings and ends of all my volumes where *not* according to NT6 (Win7) rules, so all the offsets followed the 63 sector legacy offset rule (as in WinXP).

Johan

Edited February 22, 2012 by DiracDeBroglie

[Ponch]

What about GPartEd or PartEd Magic ?

Sometimes taking a Ghost image and reapplying it on a predefined (sizewize) partition is faster.

[DiracDeBroglie]

Just had a look at the Parted Magic and GParted website. Looks like GParted can aligne partitions along NT6 rules. However, I didn't see any info about the possibility installing GParted, or PM for that matter, on Windows 7. I need to do tests on an external drive; so there is no need for me to start putting time in burning Live CDs or DVDs.

According to your experience, is there a version of GParted and/or PM that can be installed on Win7?

Have you used GParted or PM before on extended NTFS partitions?

Johan

[Tripredacus]

PartED Magic (not to be confused with the other "PM" Partition Magic) looks to be used by burning it to a CD and then booting off it?

[jaclaz]

If I were you I would try "tricking" Windows 7 to believe that that Logical partition is a Primary one.

What happens if you change the partition ID in the MBR from 0F to (say) 12?

(of course this may work ONLY to shrink from the initial Logical Partition size to the end of last logical volume in it or to expand the size of the Logical partition "to the right")

If you are into experimenting "foreign" tools/Os, I woulsd suggest you to make a test with Partition Logic CD/iso:

http://partitionlogic.org.uk/

as it has a few nice features....

jaclaz

[Ponch]

I didn't see any info about the possibility installing GParted, or PM for that matter, on Windows 7.

I've only ever seen Partition Magic working on the fly (and for instance shrinking its own system partition). All other partitionning programs I've ever seen had to be ran "offline". Both programs I talked about are running under Linux, not MS OSs. It doesn't take much time to burn a 100Meg iso.

Is this all for a "one shot" or are you planning to modify loads of drives ? Or is it just for the theory ?

[DiracDeBroglie]

I just found what I was looking for and that is called GParted; Ponch, many thanks. I've tested GParted liveCD, and it passed with flying colors; LiveCD version (gparted-live-0.12.0-2.iso) from

http://sourceforge.net/projects/gparted/files/gparted-live-stable/0.12.0-2/

See also links

http://gparted.sourceforge.net/

http://partedmagic.com/doku.php?id=programs&s[]=gparted

GParted can perform operations on the extented partition without touching the logical volumes in the extended partition. I've done the test with an extended partition with 5 logical volumes in it. GParted can shift the beginning as well as the end of the extended partition to the left and to the right, provided there is unallocated space outside the extended partition and free space inside the extended partition.

GParted also allows to align partition boundaries to the legacy 63 sector cilinders, or to NT6 rules (Win Vista, Win7). In the Resize/Move pane there is the option for alignment: Cilinder or MiB. (Cilinder = 63 sector offset, MiB = NT6 rule)

GParted: great flexibility, up to date, lean and mean; just what I was looking for.

Johan