Virtualization

Virtualization:
Allow multiple Operating System instances to run concurrently on a single computer. it is a mean of seperating hardware from single Operating System.
Each guest OS is managed by virtual machine monitor (VMM). Also known as Hypervisor, because the virtulization sits between guest and hardware. It can control guest's CPU,memory storage and even allowing a guest OS to migrate from one machine to another. It is the creation of Virtual (rather than actual) version of something such as OS,Server,Storage device or N/W resources.

Why Virtualization:

• Increase manageability,security and flexibility in (H/S) IT environment
• Provide maximum system utilization by consolidating multiple environment in single server/PC
• By abstracting s/w away from underlying h/w- new usage model opens up that reduce cost, increase management, efficiency, strengthen security, while making your computing infrastructure more resilient in event of disaster.
• Reduce power and cooling requirement.

Advantage of Virtualization

• Server Consolidation
• Reduce power and cooling requirement
• Green computing
• Ease of Deployment and administration
• High availability and disaster recovery

About VMWare Virtual Machine Server

Steps of Configure Virtual Machine

1. Right click in right panel of vmware > Add Virtual Machine

2. Select path where you want to store your virtual machine (or space of virtual machine)

3. Select network path

4. Add disk size

5. Add ram

6. Start virtual machine

7. Install operating system

8. Install vmware tools

9. Give computer name

10. Give IP of computer

11. Set firewall off (as per requirement)

12. Add required software

13. Take snapshot

VMWare -Virtual Machine File types

1. Windows Server 2003 Enterprise Edition-000001.vmdk – Vmware virtual disk file

2. Windows Server 2003 Enterprise Edition.vmsd –VMSD file

3. Windows Server 2003 Enterprise Edition.vmx – vmware configuration file

4. Windows Server 2003 Enterprise Edition-Snapshot7.vmsn- VMware virtual machine snapshot file

5. vmware.log –vmware log file

VMDK is virtual disk file - virtual partition with data and installed operating system (Micosoft Windows, Linux, Mac OS X, MS-DOS etc.) and used by VMware to run as a virtual machine (under host operating system).

This is a virtual disk file, which stores the contents of the virtual machine's hard disk drive.
A virtual disk is made up of one or more .vmdk files. If you have specified that the virtual disk should be split into 2GB chunks, the number of .vmdk files depends on the size of the virtual disk. As data is added to a virtual disk, the .vmdk files grow in size, to a maximum of 2GB each. (If you specify that all space should be allocated when you create the disk, these files start at the maximum size and do not grow.) Almost all of a .vmdk file's content is the virtual machine's data, with a small portion allotted to virtual machine overhead.
If the virtual machine is connected directly to a physical disk, rather than to a virtual disk, the .vmdk file stores information about the partitions the virtual machine is allowed to access.
Earlier VMware products used the extension .dsk for virtual disk files.

-.vmdk
This is a redo-log file, created automatically when a virtual machine has one or more snapshots. This file stores changes made to a virtual disk while the virtual machine is running. There may be more than one such file. The e2_# indicates a unique suffix added automatically by VMware Workstation to avoid duplicate file names.

Log files – Log files are just that- a log of virtual server activity for a single virtual server. Log files should be used only when you are having trouble with a virtual machine.

VMEM – A VMEM file is a backup of the virtual machine’s paging file. It will only appear if the virtual machine is running, or if it has crashed.

VMSN & VMSD files – these files are used for VMware snapshots. A VMSN file is used to store the exact state of the virtual machine when the snapshot was taken. Using this snapshot, you can then restore your machine to the same state as when the snapshot was taken. A VMSD file stores information about snapshots (metadata). You’ll notice that the names of these files match the names of the snapshots.

NVRAM files – these files are the BIOS for the virtual machine. The VM must know how many hard drives it has and other common BIOS settings. The NVRAM file is where that BIOS information is stored.

VMX files – a VMX file is the primary configuration file for a virtual machine. When you create a new virtual machine and answer questions about the operating system, disk sizes, and networking, those answers are stored in this file. As you can see from the screenshot below, a VMX file is actually a simple text file that can be edited with Notepad.

What is a VMware Shapshot?

A snapshot is a picture of your system at the time the snapshot is taken. Think of it as an image of your computer’s hard drive. Besides just the data on the hard drive, the VMware configuration for that virtual machine and the BIOS configuration are also saved when you take a snapshot. The snapshot files that are created contain only the changes that have occurred to the virtual machine since the snapshot was taken. Thus, over time, the snapshot files will grow as the machine is used more and more.

What Snapshot files are created?

When a snapshot is created a number of files are created in the directory for that virtual machine.

• -SnapshotX.vmsn (Where X is the number of the snapshot taken) This file stores the state of the virtual machine when the snapshot was taken.
• -SnapshotX.vmem (Where X is the number of the snapshot taken) This file stores the state of the virtual machine memory when the snapshot was taken.
• -nnnnnn.vmdk (where nnnnnn is the number of the disk image, not corresponding to the snapshot number) These are log files which store changes to the virtual machine, since snapshot was taken. There may be many of these files over time.

Snapshots in Workstation vs Server

VMware Workstation has the ability to create multiple snapshots and offers a very nice Snapshot Manager. The Snapshot Manager was introduced in VMware Workstation 5.0. With Snapshot Manager, you can view the snapshot tree. Each snapshot will be represented by a screenshot of what the screen looked like when the snapshot was taken. VMware Server lacks two important features: Snapshot Manager (multiple snapshots) and virtual machine cloning. In other words, in VMware server, you can only take a single snapshot and then revert back to that snapshot.

One alternative to taking snapshots that can be used in VMware Server is to shutdown the virtual machine and copy the vmdk, vmem, vmx, and nvram files. Later you could replace these files and your virtual machine would be back at the point of when that copy was made. This is a manual way of taking snapshots. However, this method takes much more disk space when compared to snapshots.

Summary

VMware snapshots are an extremely valuable feature of VMware. Currently, VMware workstation offers the Snapshot Manager, which offers the possibility of multiple snapshots. Currently, VMware Server offers only the ability to take a single snapshot. With snapshots, you can save the state of your virtual system BEFORE you make risky changes like installing applications, adding a new patch, or making a configuration change. When things go wrong, Snapshots can really save your day

Useful Commands and Concepts

Useful Commands

1. To know system information

Start>Run>Winmsd.exe

2. To know IP configuration

Start>Run>cmd>ipconfig /all

3. To know MAC address of system

Start>Run>cmd>ipconfig /all – in this physical address with 6 set of character is mac address of system

4. To see services running

Start>Run>services.msc

5. To connect remote pc

Start>Run>mstsc

6. Open the Group Policy Object Editor

Start>Run>gpedit.msc

7. To open registry

Start>Run>Regedit

8. To connect other pc

Start>Run>Ping computername or ip

9. To set disk quota

Start>Run>gpedit.msc

Computer Configuration > Administrative Templates > System > Disk Quotas.

10. To get disk signature number of your machine

Start>Run>Cmd>Diskpart

Diskpart>select Disk 0

Diskpart>detail disk

11. To open task manager

Ctrl+shift+Esc

12. To create hardlink file

Start>Run>cmd

Go to folder directory

>fsutil hardlink create “new file path” “old filepath”

v To Enable role of Hyper V in windows server 2008 64 bit or R2

Steps

· Go to server manager

· Roles

· Add role

· Select Hyper V and follow wizard.

v To install IIS role in windows server

Steps

· Go to server manager

· Roles

· Add role

· Select Hyper V and follow wizard.

v To create Hard link on windows system

Steps

· Create c:\Test.txt file (any type of file)

· Start>Run>Cmd

· >Cd \

· >fsutil hardlink create “c:\test2.txt” “c:\test.txt”

v To create Hard link on Unix

· To create a hard link of the file /export/home/fred/stuff to /var/tmp/thing, use:

ln /export/home/fred/stuff /var/tmp/thing

· The syntax for creating a hard link of a directory is the same. To create a hard link of /var/www/html to /var/www/webroot, use:

ln /var/www/html /var/www/webroot

v Steps of Configure Virtual Machine

· Right click in right panel of vmware > Add Virtual Machine

· Select path where you want to store your virtual machine (or space of virtual machine)

· Select network path

· Add disk size

· Add ram

· Start virtual machine

· Install operating system

· Install vmware tools

· Give computer name

· Give IP of computer

· Set firewall off (as per requirement)

· Add required software

· Take snapshot

Hard link

A hard link is the file system representation of a file by which more than one path references a single file in the same volume.

Any changes to that file are instantly visible to applications that access it through the hard links that reference it. However, the directory entry size and attribute information is updated only for the link through which the change was made. Note that the attributes on the file are reflected in every hard link to that file, and changes to that file's attributes propagate to all the hard links. For example if you reset the READONLY attribute on a hard link to delete that particular hard link, and there are multiple hard links to the actual file, then you will need to reset the READONLY bit on the file from one of the remaining hard links to bring the file and all remaining hard links back to the READONLY state.

Any number of hard links to the physical data may be created. To access the data, a user only needs to specify the name of any existing link; the operating system will resolve the location of the actual data.

If one of the links is removed with the POSIX unlink function (for example, with the UNIX 'rm' command), then the data is still accessible through any other link that remains. If all of the links are removed and no process has the file open, then the space occupied by the data is freed, allowing it to be reused in the future. This semantic allows for deleting open files without affecting the process that uses them

Limitation of Hard link

1) Most modern operating systems don't allow hard links on directories to prevent endless recursion.

2) Hard links can only be created to files on the same file system. If a link to a file on a different file system is needed, it may be created with a symbolic link.

3) The maximum number of hard links to a single file is limited by the size of the reference counter: with NTFS this is limited to 1023 because a 10 bit field is used for this purpose. On Unix-like systems the counter is usually machine word-sized (32 or 64-bit: 4294967296 or 18446744073709551616 links, respectively).

Disk Quotas

The NTFS file system supports disk quotas, which allow administrators to control the amount of data that each user can store on an NTFS file system volume. Administrators can optionally configure the system to log an event when users are near their quota, and to deny further disk space to users who exceed their quota. Administrators can also generate reports, and use the event monitor to track quota issues.

Basics of Virtuallization

What is Virtualization?

Virtualization is a general and ambiguous term that typically means to run multiple instances of something inside something that was intended to only run a single instance.

Virtualization is the creation of a virtual operating system, a server, a storage device or network resources. (rather than actual) version of something, such an operating system, a server, a storage device or network resources.

Operating system virtualization is the use of software to allow a piece of hardware to run multiple operating system images at the same time. The technology got its start on mainframes decades ago, allowing administrators to avoid wasting expensive processing power.

• Network virtualization is a method of combining the available resources in a network by splitting up the available bandwidth into channels, each of which is independent from the others, and each of which can be assigned (or reassigned) to a particular server or device in real time. The idea is that virtualization disguises the true complexity of the network by separating it into manageable parts, much like your partitioned hard drive makes it easier to manage your files.
• Storage virtualization is the pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console. Storage virtualization is commonly used in storage area networks (SANs).
• Server virtualization is the masking of server resources (including the number and identity of individual physical servers, processors, and operating systems) from server users. The intention is to spare the user from having to understand and manage complicated details of server resources while increasing resource sharing and utilization and maintaining the capacity to expand later.

How do we get virtualization?

Well there is no. of options available for this, but VMware, Citrix and Microsoft are front runners in domain. Here are the products from above for the same.

1. VMware ESX and VMware server
2. Citrix Xen
3. Microsoft Hyper-V

VMware Server:

VMware Server is a free virtualization product for Microsoft Windows and Linux servers. It enables you to quickly provision new server capacity or server consolidation by partitioning a Physical server into multiple virtual machines. It is meant for those businesses who want to optimize use of their technology assets using virtualization.

Technology behind VMware Server:

• Hypervisor – 2 (Hosted Architecture)

What is Hosted Architecture?

Hosted architecture is where your virtualization software is installed as an application onto the pre-existing host operating system. This means that your virtualization layer relies on your host operating system for device support and physical resource management. VMware Server is a good example of a hosted architecture.

Hardware and Software support:

1. Any standard x86 compatible or x-86-64compatible personal computer
2. A wide variety of Windows, Linux, Solaris, and other guest operating systems,

Including 64-bit operating systems

3. Two-way Virtual SMP
4. Intel Virtualization Technology (Intel VT)
5. AMD-Virtualization (AMT-V)

Where VMware Server does fits for your environment?

VMware server suits the requirements and demands of small and medium scale business with non-mission critical processes. It can provide following options to the business resources.

1. Virtual Machines for software development:
1. A common environment matching in both configuration and tools for your entire team
2. Quick rollout of new environments and tools
3. Archive of entire development environments for major projects

2. Virtual Machines for software testing:
1. Platform Testing with Snapshots
2. Platform Testing with Persistent and Non-persistent Disks

3. Virtual Machines for Post-release and Application-Maintenance.
1. It can create base image for you development environment
2. Archive of the development team’s virtual machines used during the development phase
3. Rapid platform availability for quick support tasks and bug investigation

4. Run Windows, Linux, and other operating systems and applications without

Software conflicts.

5. Move virtual machines from one physical host to another without having to

Reconfigure them.

Features of VMware Server:

1. Web-Based Interface

Use VMware Infrastructure Web Access (VI Web Access) to perform host and virtual machine configuration for VMware Server 2.0.

1. Create, configure, and delete virtual machines
2. Add and remove virtual machines from the inventory
3. Perform power operations (start, stop, reset, suspend, and resume) on virtual Machines
4. Monitor the operation of virtual machines
5. Generate a Web shortcut to customize the VI Web Access user interface for users, with the option to limit their view to the console or a single virtual machine
6. Generate a VMware Remote Console desktop shortcut that allows virtual machine users to interact directly with the guest operating system outside of a Web browser
7. Configure host-wide VMware Server settings

2. VMware Remote Console

VMware Remote Console enables you to interact with the guest operating system

running in a virtual machine. You can run VMware Remote Console on the host or a remote client system. After you install it as a Web browser add-on from VIWeb Access, VMware Remote Console can run independently from VIWeb Access.

VMware Remote Console also allows you to connect and disconnect client CD/DVD

and floppy devices.

3. Memory Support

The maximum amount of memory that can be allocated per virtual machine is

8GB. The amount of memory that can be used by all virtual machines combined is limited only by the amount of memory on the host computer.

4. Number of Network Adapters Supported

It can support total of 10 network adapters for a virtual machine.

5. Quiesced Backups of Virtual Machines on Windows

On Windows hosts, you can enable the VMware VSS Writer, which uses snapshots to

maintain the data integrity of applications running inside the virtual machine when

you take backups.

6. Support for High-Speed USB 2.0 Devices

If the guest operating system has the appropriate USB 2.0 device drivers, you can use peripherals that require high-speed performance, such as speakers, webcams,

next-generation printers and scanners, fast storage devices, MP3 players, DVD-RW

drives, and high-capacity CD-ROM jukeboxes.

Besides above there are few more such as

· Additional host operating system support

· Additional guest operating system support

· improved 64 bit guest support

· 64 bit sound driver

· Native 64 bit support on linux

· Improved VIX-API

· VMCI socket interface

Bottlenecks:

1. It puts more of your client's eggs in one basket. If the host machine breaks or needs to be taken offline, several virtual servers will go down.
2. Applications like databases that require a lot of disk activity. The prevailing wisdom is that databases should still run on dedicated physical servers.
3. Time-sensitive applications like Voice over IP (VoIP) may also be poor candidates for virtualization.
4. Virtual Machine overload: Application that are low I/O intensive and low utilization are best candidates for virtualization but need to put restriction on no. of virtual machines that can be handled with ease on physical server.

VMware Server at a glance:

Architecture	Hosted
OS Requirements	Windows or Linux
Typical Use Cases	Test & Dev, Production
Dedicated Server Required	No
Centralized Management Option	No
Ease of Use	High
Performance	Good