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When not to convert basic disks to dynamic disks

Converting basic disks to dynamic disks can help achieve improved performance in your Windows OS. However, there are compatibility restrictions you should be aware of before diving into this conversion process.

Dynamic disks have a lot of advantages over basic disks. They allow you to improve performance with a striped volume across multiple disks and give you the option to extend a volume to include unused space on other dynamic disks within the system.

In spite of these benefits, there are situations when you should reconsider converting a basic disk into a dynamic disk.

Take a closer look at some scenarios when it's not in your best interest to convert to dynamic disk.

When downgrading your OS

This particular situation may not apply to most people, but it's still important. Dynamic disks are compatible with the Windows operating system from Windows 2000 through Windows 10. If you are running one version of the OS and planning to downgrade to an older version, then you shouldn't convert your basic disks to dynamic disks because the conversion process disables your ability to uninstall your current OS and revert to your previous version.

Multi-boot environments

If you're running a multi-boot configuration on a computer, you should not convert basic disks to dynamic disks. Although Windows 2000 through Windows 10 all support dynamic disks, you will cause problems if you convert to dynamic disk from basic disk if you have more than one Windows operating system installed on the same machine.

Problems occur when you perform the upgrade because Windows also updates certain registry entries to make the operating system aware of the presence of a dynamic disk. If these registry entries are not updated, Windows will not know how to deal with the dynamic disk. If you convert a basic disk to a dynamic disk in a multi-boot environment, the conversion works fine for the operating system that you are using at the time of the conversion. The other operating systems on the computer, however, will not be aware of the conversion, and will no longer recognize the disk.

Using legacy operating systems

Older operating systems, such as Windows 98, are not compatible with dynamic disks. These OSes are so old their incompatibility with dynamic disks probably isn't going to be an issue for the majority of people. What you should consider, though, is that there are some versions of XP that do not support dynamic disks either.

This limitation ties in to the restriction on multi-boot environments. In a multi-boot environment, if an OS at least supports dynamic disks, then the operating system may not recognize a disk once you convert it to dynamic; Windows does, however, provide mechanisms you can use to import the now "foreign" disk into the operating system.

In the case of legacy OSes, the older OS will not be able to recognize the dynamic disk at all. If you converted the boot volume, then you will not even be able to boot the older OS after the conversion.

Unknown partitions

Another disk conversion situation to avoid is when the disk contains alternate partitions Windows did not create. For example, many computers ship with OEM partitions on the system drive. If you were to convert to dynamic disk, then the OEM partitions become inaccessible.

Keep in mind that this limitation doesn't just apply to OEM partitions. The same limitation applies to any partition created by a non-Windows operating system. For example, if you multi-boot Windows and Linux on the same computer. Linux creates non-Windows partitions, so if you take a drive containing a Linux partition and convert to dynamic disk, Linux would no longer function.

Other limitations

The majority of the situations that prevent you from converting basic disks to dynamic disks are related to compatibility issues with alternate operating systems. Even within a single operating system there are some conditions that prevent you from making the conversion. For example, if you intend to install the File Allocation Table (FAT) file system on a drive, you will not be able to convert that drive to dynamic because only basic volume supports FAT.

The conversion to a dynamic disk is also typically disabled for removable drives. If you converted a removable drive to a dynamic format, then only the computer you used to perform the conversion would recognize the changes. As such, Microsoft prevents you from converting removable drives to dynamic.

As strange as it may seem, there are situations in which you cannot convert a drive on a laptop to dynamic. This limitation does not exist in Vista, but XP does prevent you from converting laptop drives to dynamic. Keep in mind though that this limitation is tied into the Advanced Configuration and Power Interface (ACPI) architecture. Therefore, if you have a really old laptop that is not ACPI compliant you can probably get away with converting a basic disk to a dynamic disk through Windows XP.

Finally, you will not be able to perform the conversion if the disk is full. Windows requires space at the end of the volume to maintain volume information. If the space is not available then the conversion process will fail.

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