Effective Hard Drive Capacity  

Most people like to have partitions on their hard drives to make the space more manageable. A system administrator might load applications in one partition and data in another, while a software developer might load multiple OSs on the system to test the same software for different platforms. While it's easy to create partitions for the first time, it is difficult to create more partitions or resize the existing ones. For instance, if you have to load a huge application on an existing partition, which does not have sufficient free space, you may have to extend the partition. Or, if you have loaded Windows on your machine and don't have free partitions to load Linux as well, you might like to shrink an existing partition and create a new partition from the spare space for Linux. In this article, we'll tell you how to shrink your existing partitions using a free tool called RPM or Ranish Partition Manager 2.4. 

RPM can create, copy and resize primary and extended partitions. It is DOS based and can only shrink partitions based on FAT and FAT32 file systems. It can be operated in two modes, namely CHS (Cylinder Head Sector) and LBA (Logical Block Addressing). CHS, as the name suggests, will show you the starting and ending cylinders, heads and sectors occupied by a partition on your hard drive. The LBA mode will show sector details, such as the number of sectors and the starting and ending sector occupied by the partition. You can switch between the two modes by pressing the F4 key while using RPM.

The utility supports disks of any sizes, having up to four primary partitions.

Before we get into using the utility, here are a couple of prerequisites. First, defragment all partitions on your hard disk. This will neatly arrange all data so that it's not scattered all over the hard drive. The next very critical step is to back up all data of the partition you're trying to shrink. If something goes wrong and you lose the partition you're trying to shrink, at least your data will be safe. Also, you can't change the original file system. Then, get yourself a bootable floppy and copy the RPM utility to it. Lastly, boot the system from the floppy and run the RPM utility. Please bear in mind that RPM is a DOS-based utility where you have to manually enter all information. Therefore, you have to be very careful, as any incorrect entries could make your disk inoperable. Now let's see how to use it. 

Step 1: Note the current MBR settings to provide a back up in case something goes wrong. In RPM, the modifications need to be made to both the partition table and the boot-sector table. This is because the partition size shown in the former is in Kilobyte,
while in the latter it is in Megabyte. The boot-sector table shows the minimum partition size that should be done. So, when you're shrinking the partition ensure that your minimum partition size doesn't go
below this. 

Step 2: Select the partition you want to resize. If you're in CHS mode, you'll be shown the starting and ending cylinder values for that partition. Here, you need to change the value of the ending cylinder. In fact, this is the only value that RPM will allow you to modify. Similarly, if you're in LBA mode, you will be able to change the ending sector value for that partition. On top of the RPM utility window, you'll see the hard drive's actual capacity and the total number of cylinders, heads and sectors. You can't exceed these values when making changes to the ending cylinder or sector values for a particular partition. There's a separate column in RPM that indicates the partition size. When you make changes to the cylinder or sector values, the resulting partition size will automatically change and be displayed here. 

When you shrink the partition, there could be errors like a cylinder number that you've entered is overlapping with another partition. Or, perhaps an error that the partition size you're creating is lower than the minimum partition size. These errors are indicated on top of the RPM window. Don't ignore these errors, as they could result in loss of your partitions, and thereby all your data. You need to rectify these errors in the partition table before you proceed to the next step. 

Step 3: The changes made in the partition above automatically get reflected in the partition table. Ensure that your cursor is in the partition column. When you're there, press Enter to get into the boot-sector table at the bottom of the screen. When you are in the boot-sector screen press X and the partition size will change and will become the same as the partition size in partition table. 

Step 4: Now press the Esc key. This will give you the option of whether you want to save the changes or not. Click on Yes and it will make the changes and exit. If you're creating a new partition, it will also ask you to format the partition. Finally, reboot your system and run the scan-disk utility to see that your partitions are all intact. 

Besides creating and copying partitions, RPM 2.4 can hide file systems and check them for bad sectors. You can save the utility to a hard drive by pressing the A key while running the utility. If you have multiple hard drives in your system, then press F5 while running RPM; it will display all hard drives in your system. Choose the one you want to modify. 

Sushil Oswal