Regardless of the OS you're using, by keeping that data separate, you can move it from system to system independently or simple be able to better keep it safe, encrypted ideally. Finally in terms of performance, by having those drives independent, you have independent physical paths to that information, hence better performance.
In some case you simply don't have multiple physical storage units. Still you can benefit from keeping data and OS separate by partitioning your hard drives. We're going to use Windows 7 as an example. To create a drive by extending a partition on an existing physical drive:
1. From the Control Panel select Administration Tools. You should see the dialog shown in Figure 1:
|Figure 1: The Administrative Tools dialog. From here you can select the Computer Management tool that will allow you to manipulate the storage units in your PC.|
2. Double click on Computer Management you should get the dialog shown in Figure 2:
|Figure 2: The Disk Management selection from the tree allows you to manage the storage units in your PC as well as the different partitions that hold your data.|
3. Select the C: main drive as shown, right mouse click on it and select "Shrink Volume" from the pop up menu. The system will analyze the drive and should show the dialog in Figure 3:
|Figure 3: The Shrink drive dialog allows you to dynamically change a partition's size. Think of this as an easy to use Norton's Partition Magic, but Free and built into Windows.|
Note: A generic recomendation is to divide this number by 2 or less. You need to set the amount in MB that you want to shrink the original partition. Recommendation is from 25 to 50% of the available space, but no higher than 50%. Notice the circled number: Divide by 2 for 50%, by 3 for 33%, by 4 for 25%. The result goes in the text box cicled in red. Remember that you need to leave space on the original partition for future use otherwise you won't have any usable space.
4. Click on the Shrink button to execute. Once the process is done, notice the Computer Management dialog. You should see a new, Unallocated space next to the main drive as shown in Figure 4:
|Figure 4: Notice a new partition which is now available. At this point it's simply allocated space which means that still it needs to be prepared for use.|
5. Rick mouse click the unallocated volume circled in Figure 4. Select the "Create a New Simple Volume" from the pop-up menu. The dialog/wizard shown on Figure 5:
|Figure 5: The New Simple Volume Wizard dialog will guide you through the steps of creating a new logical drive for data storage.|
6. Click Next and you should see the Specify Volume Size dialog. Use the maximum space available to use all of the empty volume space as shown in Figure 6:
|Figure 6: The Specify Volume Size dialog allows to enter the size that you want to use with your new partition. As a general rule, use all available space, unless you intend to create more partitions later.|
7. Click on Next and you will have a chance to assign the drive letter as shown in Figure 7. Depending on your setup, you'll have multiple options based on the available drive letters. Let's use D for this case. If the letter you want to use it’s been used by another drive such a CD-ROM, you need to go to such drive before and right mouse click on it, select “Change drive letter” and assign another letter to such drive before you do this.
|Figure 7: The assign a drive letter dialog lets you assign such to your new logical drive.|
7. After you click on Next, the Format Partition dialog shown in Figure 8 should show up. This will allow to format the new logical drive. You can add a label to better identify it. In this case we're using DATA and then we format the drive to start clean. Accept defaults and click on Next. It should format the drive for use
|Figure 8: The Format Partition dialog allows you to format your logical drive.|
9. Once you click on Next the system will Format and prepare your drive for use. You should get the dialog shown in Figure 9. At this point click on Finish to commit all actions and finalize the process.
|Figure 9: At this point you're done and this dialog confirms that.|
10. As confirmed with the dialog shown in Figure 9, you should have a new drive ready to use. A recomendation is to go back to the Computer Management dialog to confirm you have your new drive. As shown in Figure 10, you should have a usable drive partition with a letter assigned to it.
|Figure 10: Notice the new drive listed as a usable storage unit or logical drive.|
At this point the process if finalized and you should be ready to use the new logical drive. To process should be valid for both Windows Vista and 7. You do need admin rights to perform all of the previous steps. You should be able to do this in other OS systems. The important thing to remember is that to keep your applications and data separate, helps you to avoid the "all the eggs in one basket" situation hence the best way to keep you data safe.