Monday, September 17, 2012

VMware Technical Questions and Answers and Interview FAQ -Part4

31. What is VMware VCB?

VMware Consolidated Backup (or VCB) is a group of Windows command line utilities, installed on a Windows system, that has SAN connectivity to the ESX Server VMFS file system. With VCB, you can perform file level

or image level backups and restores of the VM guests, back to the VCB server. From there, you will have to find a way to get those VCB backup files off of the VCB server and integrated into your normal backup process. Many backup vendors integrate with VCB to make that task easier. Contrary to what it sounds like VCB IS NOT a traditional backup application because it doesn’t do anything to get the data off the system and onto external media nor does it have a GUI interface.
32. What is Virtual Center?

Both VMware Virtual Center and Microsoft System Center are centralized management applications for their respective virtualization platform.

Virtual Center is a required piece of many of the advanced VMware ESX Server features but it must be purchased separately. Virtual Center runs on a Windows server and it could use SQL as a backend.

33. What is System Center Virtual Machine Manager?

Microsoft System Center is Microsoft’s centralized management platform for just about every Microsoft enterprise function (“from data center to desktop”, as Microsoft says).

More specifically, Microsoft System Center Virtual Machine Manager is the centralized management platform for virtualization. Microsoft calls it their “comprehensive virtualization management tool”. It can perform virtual machine monitoring, configuration, provisioning, and administration. The latest version, VMM 2008, can manage Microsoft Hyper-V, Virtual Server 2005, and VMware ESX Server platforms.

34.What is a partition?

In virtualization terminology, a partition is what is managed by a hypervisor. That partition could have a virtual guest operating system inside of it, or the partition could be empty.

35. What are: virtual processor, virtual RAM, virtual NIC, & virtual disk?

From working with servers and PCs, you are familiar with common components like CPU, RAM, Disk, network, and so on.

When using server virtualization, each guest operating system will have its own virtual components such as the virtual CPU, virtual memory (RAM), virtual disk, virtual network, and so on.

Inside the guest operating system, the OS will see these devices as physical devices and you may or may not have the vendor’s virtualization driver loaded for that device. These virtual devices are configured in the virtual guest configuration for that VM, in the management interface for your virtualization software.

36. Why do I need to care about the hardware requirements of VMware ESX and Microsoft Hyper-V?

Type 1 virtualization platforms that run on the bare metal of your server hardware will have specific hardware requirements because they are not typical applications that run inside an underlying (host) operating system. Because of this, type-1 virtualization platforms will have strict hardware requirements. For example, Hyper-V must run on 64 bit hardware and VMware ESX Server only support certain disk storage systems and network interface cards.

For more information on the hardware requirements of these two virtualization platforms, please see: Microsoft Hyper-V Hardware Requirements
VMware ESX Server Hardware Compatibility List (HCL)

37.What is a snapshot?

A snapshot is a “point in time image” of a virtual guest operating system (VM). That snapshot contains an image of the VMs disk, RAM, and devices at the time the snapshot was taken. With the snapshot, you can return the VM to that point in time, whenever you choose. All changes made after the snapshot was taken may be based on that snapshot information (incremental changes). You can take snapshots of your VMs, no matter what guest OS you have and the snapshot functionality can be used for features like performing image level backups of the VMs without ever shutting them down. Do not confuse Virtual Machine Snapshots with Microsoft’s VSS (Microsoft’s Volume Shadow Copy Service). Snapshots can be taken in just about every virtualization platform available.

38.What is Quick Migration?

Quick Migration is a feature of Microsoft’s Hyper-V virtualization platform. With Quick Migration, you can move running virtual machines from one host to another host server with minimal downtime. This feature is comparable to VMware’s VMotion except Quick Migration, in its current incarnation, is not as quick as VMotion (VMotion is about 1 second vs Quick Migration of about 5-20 second)

39. Why won’t my virtualization product boot from my OS CD to load my new guest OS?

Many times, admins have complained that they could not access or could not boot a virtual CDROM that was inserted or an ISO file that was mapped.

And so many times, the cause of this issue is just a simply click. To access a virtual CDROM, that CDROM must be connected. If you look at the graphic below, you can see how the device is both connected and connected at power on. Connected devices are connected after the VM boots where as connected at power on devices, are connected before the VM boots. To boot a new OS CD, that CDROM needs to be connected at power on.

40. What do I need to know about licensing and Virtualization?

Concerning licensing and virtualization – the most important thing to know is that any guest operating system must have a license, just as any physical server or workstation does. Thus, if you run Microsoft Virtual Server on Windows Server 2003 and 3 guest operating systems are running (Windows XP, Windows Server 2008, and Windows Vista), you must have 4 Microsoft operating system licenses – Windows XP, Windows Vista, Windows Server 2003, and Windows Server 2008.

As Linux is typically open source, you can generally have as many Linux guest operating systems as you want without paying any licensing fees.

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