How to Extend C Drive (OS partition) in Dell Factory Installed Microsoft Windows Server OS?

When you order a Microsoft Windows Server from Dell with a Microsoft Server OS factory installed in it, the order page gives you the option to select from three partitioning options as 40GB, 80GB and Max partition (This will create OS partition of full disk). If you don’t choose any of these options, you will receive a server with 40GB OS partition which is a default size of factory installed system.

Some customers may need to increase this default size, as their business needs change. In this blog I have discussed different options you can exercise to extend your OS partition size.

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Fig: 1

Note: Throughout the below discussion, OS partition or OS volume is C:\ and Data partition or Data Volume is D:\ in Disk 0 similar to the figure 1.

Limitation 1: You cannot extend OS partition if there is no contiguous unallocated space on the right side of OS partition. In such case, the "Extend Volume" option will be greyed out in the disk management console.

Limitation 2: You cannot extend OS partition by shrinking data partition behind it. Because "Shrink Volume" feature only generates unallocated space on the right side of the partition you shrink.

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Fig: 2

Option 1: When you have not started using the Data partition adjacent to the OS partition

1. From Command Prompt, type diskmgmt.msc to open Disk Management console.
2. Delete the Data partition to get unallocated space similar to the figure 2 in Disk 0.
   1. Right click D drive and select "Delete Volume". If the Data partition is part of extended partition, then right click on the partition and select “Delete Partition”
3. Now right click on OS partition and you will see “Extend Volume” option is enabled.
4. Click Extend Volume to increase the OS partition size of your wish.
5. Create a Data partition using the remaining unallocated space.

Option 2: When you have already started using the Data partition adjacent to the OS partition

1. Take backup of your Data partition to a Removable disk or to another partition in different disk other than disk 0. You can do it simply by copying the files to another location or using Windows Server Backup tool or third party backup tool.
2. From Command Prompt, type diskmgmt.msc to open Disk Management console.
3. Delete the Data partition to get unallocated space similar to the figure 2 in Disk 0
   1. Right click D drive and select "Delete Volume". If the Data partition is part of extended partition, then right click on the partition and select “Delete Partition”
4. Now right click on OS partition and you will see “Extend Volume” option is enabled.
5. Click Extend Volume to increase the OS partition size of your wish.
6. Create a Data partition using the remaining unallocated space and copy back all the content.

Option 3: Third party disk partitioning tool.

There are different disk partition tools available in market to resize the partitions in the system. You need to carefully select the tools based on your requirement. Here are couple of points to consider while choosing the tool:

1. Will the tool supports MBR boot disk or uEFI boot disk or both?
2. Factory systems already come with three primary partitions in case of MBR boot (Legacy BIOS) and 4 Primary partition in case of GPT boot (uEFI BIOS). So, disk partitioning tools may not able to work properly in MBR boot disk as they can’t resize the Data partition which is part of the extended partition. In such case, you need to consider option 1 or 2 based on your requirement.
3. Even though third party tools can resize the partition without a need for taking a backup, it is always recommended to take a backup to avoid any data loss.

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