Question

While creating a virtual hard drive, suppose you select dynamically allocated hard drive.

• Discuss the pros and cons of this choice.

Now after this you are asked to do the same with the fixed size option.

• How does this affect the creation of hard drive in some aspects and the overall performance of our system being installed?
• Also discuss the pros and cons of such installation

Please use more than 300 words

Answer 1

Virtual Hard Drive - Dynamically Allocated Hard Drive

Virtual hard drives give you the authority to create dynamic size allocation so that there is no need to occupy or allocate all the disk space at once. Its size will only increase as you add data in it. It behaves like a single file and It is very easy for it to backup. You can create the dynamic virtual hard drive install an operating system and dual boot it. Whenever you store anything in the disk only then it will increases its size. This is the way of virtualization is used to manage or utilize the wasted storage space in your system.

When we create a new virtual memory, we don't even know how much virtual space is required and we also don't want that our disk running out of space.Before the dynamic allocation concept came in figure, many administrator would just add some bits more what it actually required. But the problem with this concept it actually waste the disk space. Every virtual memory will take memory which may or may not be used by it.

So the solution for this is to use dynamic allocation that allow us to set the maximum file of virtual hard drive file just as you always have. Here the difference is that the actual physical space is not acquired till the virtual memory needs it. Here the disk start with very small and depends on how large it needs to be depending on the files. As we add data to the virtual hard drive, the virtual hard drive dynamically large to keep the data.

Here some of the cons are also involved for using dynamic allocation like;

i. If you write a large file in the virtual hard drive, it will expand to allocate the data and if you delete this file the virtual hard drive will not shrink and it's also not easy to reclaim the space.

ii. It also complicate the virtual storage management. The problem is that because the virtual hard drive files expand, the logical unit number may out of physical storage. When it happens there are only two way that you can either move your virtual memory to another storage or you can add additional storage.

Dynamic allocation has its own merits and demerits, but the merits are outweighs the risks and use de-fragmentation software to maintain optimal performance.

Fixed size virtual hard drives

A fixed size is used where the platform need a fixed size memory or adding extra memory for virtual machine. In fixed disk the disk is given the maximum capacity size that can be seen from the operating system. On the host the virtual disk file is created with .vmdk file extension. The size of the file is same as the time when it it is created is same as what we created for disk capacity to be. It remains constant and it does not grow and shrink. When we create a fixed size disk the space we specify is automatically allocated and reserved for that virtual machine. There are some advantage of using fixed storage fixed size virtual storage even though it takes so much space when they are empty.

First, predictability - By creating only fixed size you can be so sure that you can not run out of physical storage unexpectedly on the host.

Second, reliability - If the power failure comes in frame and affect the host of data center, any dynamically expanding virtual disk storage requirement are planned carefully.

But there is one of the most downfall of fixed size is that if they are not as much utilized , the physical storage will be waste at the host. Another demerit is that they are heavy in size this means it can be slower to migrate and backup.