Calculating offset for start of partition

  Nosmas 19:50 05 Mar 2010

I have installed Windows 7 and wish to create a Logical Partition within an Extended Partition. Unfortunatley W7 (and apparently Vista) Disk Management no longer provide the facility for doing this (see click here), so I am endeavouring to do this using Diskpart. I want to start the Extended Partition about halfway along a 500GB disk and then to create a Logical Partition within the Extended.

My problem is in calculating the offset parameter for the Extended Partition to enter into the command in order to achieve this. All help with this gratefully accepted.

  Nosmas 00:55 06 Mar 2010

Just to add a bit more information to the above to explain what I am trying to do. The layout of the disk is presently: -

1. C: Windows 7 Primary 30.01GB NTFS
2. Unallocated 208.38GB
3. Primary (not yet used) 25.0GB NTFS
4. Unallocated 208.37GB NTFS

I wish to make the whole of item 4 an Extended Partition,using the following in DiskPart: -

Create partition extended offset=???

and then to create a Logical Partition within it,
(leaving out the Size parameter should result in all the unallocated space being encompassed in the Extended Partition).

I have tried various calculations of the Offset parameter but all have resulted in DiskPart issuing a message "Virtual Disk Service error. There is not enough space for this operation."

Can someone tell me what I am doing wrong and give me the correct method for creating the Extended Partition. I don't understand why the message is referring to 'Virtual' because I am dealing with a 'physical' disk.

  beeuuem 01:17 06 Mar 2010

Would it not be easier to use a partition manager such as click here ?

  Zeppelyn 05:16 06 Mar 2010

The easiest way to create an extended partition using Diskpart is to firstly create a temporary primary partition at your point no.2 then when you use the command "create partition extended" it will automatically use the first free space. This way you do not need to specify an offset.

  Nosmas 14:16 06 Mar 2010

beeuuem - Many thanks for your reply and suggestion. I had already downloaded Easeus Partition Master (v5.0.1) but although it performs many more functions than the W7 inbuilt Disk Management, strangely it only permite the creation of Primary and Logical partitions - no mention of Extended partitions.

Zepplyn - Thank you also for your suggestion. Whilst waiting for replies to my post, I had been mulling over that very idea and have now created the temporary Primary, an Extended and a Logical within the Extended. Curiously, going to DiskPart and entering the command 'List Partition' it shows the offset for Extended as 260 which is one of the values I tried but which brought up the eror message.

On the subject of Easeus I have found their products - Partition Master and Todo Backup very good so far. EPM also includes a facility to burn a bootable disk. Their support were also very prompt to answer a problem I put to them, although some of their English was a bit difficult to understand. I have previously used Acronis True Image but was very put off after making and validating two images of my XP system partiton and Data partition, only to find that one was declared 'corrupted' and the other 'was not an Acronis TI file' when I wanted to restore them!!!

  Zeppelyn 15:06 06 Mar 2010

Glad you got sorted Nosmas, I find Diskpart very useful and also its quite straight forward to use too. I use Todo Backup too, I find Acronis wants to hold your hand to much for my liking, especially the latest versions.

  Batch 16:46 06 Mar 2010

Some partition management software automatically creates an extended partition when you attempt to create the first logical partition (so you don't have to create the extended partition). So maybe Easeus Partition Master would do the job.

Else try something else like Paragon Partition Manager

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