VMWare Training

Software-defined data center (SDDC), all infrastructure is virtualized, and the control of the
data center is automated by software. vSphere is the foundation of the .
-TRAINING

A virtual machine uses virtual hardware. Each guest operating system sees ordinary hardware
devices. The guest operating system does not know that these devices are virtual. All virtual
machines have uniform hardware, except for a few variations that the system administrator can
apply. Uniform hardware makes virtual machines portable across VMware virtualization platforms.
You can configure virtual machine memory and CPU settings. VMware vSphere® supports many of
the latest CPU features, including virtual CPU performance counters. You can add virtual hard disks
and NICs. You can also add and configure virtual hardware, such as CD/DVD drives, floppy drives,
and SCSI devices. Not all devices are available to add and configure. For example, you cannot add
video devices, but you can configure available video devices and video cards.
You can add multiple USB devices, such as security dongles and mass storage devices, to a virtual
machine that resides on a VMware ESXi™ host to which the devices are physically attached. When
you attach a USB device to a physical host, the device is available only to virtual machines that
reside on that host. Those virtual machines cannot connect to a device on another host in the data
center. A USB device is available to only one virtual machine at a time. When you remove a device
from a virtual machine, it becomes available to other virtual machines that reside on the host.
You can add up to 16 PCI VMware vSphere® DirectPath I/O™ devices to a virtual machine. The
devices must be reserved for PCI pass-through on the host on which the virtual machine runs.
Snapshots are not supported with vSphere DirectPath I/O pass-through devices.

What are virtual machine files made up of?
The .nvram file. This small file contains the BIOS that is used when the VM boots. It is similar to a physical server that has a BIOS chip that lets you set hardware configuration options. A also has a virtual BIOS that is contained in the NVRAM file. The BIOS can be accessed when a VM first starts up by pressing the F2 key. Whatever changes are made to the hardware configuration of the VM are then saved in the NVRAM file. This file is in binary format and if deleted it will be automatically recreated when a VM is powered on.

The .vmx file. This file contains all of the configuration information and hardware settings of the virtual machine. Whenever you edit the settings of a virtual machine, all of that information is stored in text format in this file. This file can contain a wide variety of information about the VM, including its specific hardware configuration (i.e., RAM size, network interface card info, hard drive info and serial/parallel port info), advanced power and resource settings, VMware tools options, and power management options. While you can edit this file directly to make changes to a VM's configuration, don't do this unless you know what you are doing. If you do make changes directly to this file, make a backup copy first.

VMDK files. All virtual disks are made up of two files, a large data file equal to the size of the virtual disk and a small text disk descriptor file, which describes the size and geometry of the virtual disk file. The descriptor file also contains a pointer to the large data file as well as information on the virtual disks drive sectors, heads, cylinders and disk adapter type. In most cases these files will have the same name as the data file that it is associated with (i.e., myvm_1.vmdk and myvm_1-flat.vmdk). You can match the descriptor file to the data file by checking the Extent Description field in this file to see which -flat, -rdm or -delta file is linked to it.

The -delta.vmdk file. These VMDK files are only used when making snapshots. When a snapshot is created, all writes to the original -flat.vmdk are halted and it becomes read-only; changes to the virtual disk are then written to these -delta files instead. The initial size of these files is 16 MB and they are grown as needed in 16 MB increments as changes are made to the VM's virtual hard disk. Because these files are a bitmap of the changes made to a virtual disk, a single -delta.vmdk file cannot exceed the size of the original -flat.vmdk file. A delta file will be created for each snapshot that you create for a VM and their file names will be incremented numerically (i.e., myvm-000001-delta.vmdk, myvm-000002-delta.vmdk). When the snapshot is deleted, these files are automatically deleted after they are merged back into the original flat.vmdk file.

The -rdm.vmdk file. This is the mapping file for the raw device mapping (RDM) format that manages mapping data for the RDM device. The mapping file is presented to the ESX host as an ordinary disk file, available for the usual file system operations. However, to the VM, the storage virtualization layer presents the mapped device as a virtual SCSI device. The metadata in the mapping file includes the location of the mapped device (i.e., name resolution) and the locking state of the mapped device. If you do a directory listing, you will see that these files will appear to take up the same amount of disk space on the VMFS volume as the actual size of the LUN that it is mapped to, but in reality they just appear that way and their size is very small. One of these files is created for each RDM that is created on a VM.

The .vswp file. When you power on a VM, a memory swap file is created that can be used in lieu of physical host memory if an ESX host exhausts all of its physical memory because it is overcommitted. These files are created equal in size to the amount of memory assigned to a VM, minus any memory reservations -- default is 0 -- that a VM may have set on it (i.e., a 4 GB VM with a 1 GB reservation will have a 3 GB VSWP file created). These files are always created for virtual machines but only used if a host exhausts all of its physical memory. As virtual machine memory that is read/written to disk is not as fast as physical host RAM, your VMs will have degraded performance if they do start using this file. These files can take up quite a large amount of disk space on your VMFS volumes, so ensure that you have adequate space available for them, as a VM will not power on if there is not enough room to create this file. These files are deleted when a VM is powered off or suspended.

The .vmss file. This file is used when virtual machines are suspended and is used to preserve the memory contents of the VM so it can start up again where it left off. This file will be approximately the same size as the amount of RAM that is assigned to a VM -- even empty memory contents are written. When a VM is brought out of a suspended state, the contents of this file are written back into the physical memory of a host server, however the file is not automatically deleted until a VM is powered off -- an OS reboot won't work. If a previous suspend file exists when a VM is suspended again, this file is reused instead of deleted and recreated. If this file is deleted while the VM is suspended, then the VM will start normally and not from a suspended state.

The .vmsd file. This file is used with snapshots to store metadata and other information about each snapshot that is active on a VM. This text file is initially 0 bytes in size until a snapshot is created. A VMSD file updates with information every time snapshots are created or deleted. Only one of these files exists regardless of the number of snapshots running, as they all update this single file. The snapshot information in a VMSD file consists of the name of the VMDK file and VMSN file used by each snapshot, the display name and description, and the UID of the snapshot. Once your snapshots are all deleted, this file retains old snapshot information but increments the snapshot UID to be used with new snapshots. It also renames the first snapshot to Consolidate Helper, presumably to be used with consolidated backups.

The .vmsn file. This file is used with snapshots to store the state of a virtual machine when a snapshot is taken. A separate .vmsn file is created for every snapshot that is created on a VM and is automatically deleted when the snapshot is deleted. The size of this file will vary based on whether or not you choose to include the VM's memory state with your snapshot. If you choose to store the memory state, this file will be slightly larger than the amount of RAM that has been assigned to the VM, as the entire memory contents, including empty memory, is copied to this file. If you do not choose to store the memory state of the snapshot then this file will be fairly small -- under 32 KB. This file is similar in nature to the .vmss that is used when VMs are suspended.

The .log file. LOG files are created to log information about the virtual machine and are often used for troubleshooting purposes. There will be a number of these files present in a VM's directory. The current log file is always named vmware.log and up to six older log files will also be retained with a number at the end of their names (i.e., vmware-2.log). A new log file is created either when a VM is powered off and back on or if the log file reaches the maximum defined size limit. The number of log files that are retained and the maximum size limits are both defined as VM advanced configuration parameters -- log.rotateSize and log.keepOld.

The .vmxf file. This file is a supplemental configuration file that is not used with ESX but is retained for compatibility purposes with VMware Workstation. It is in text format and is used by Workstation for VM teaming where multiple VMs can be assigned to a team so they can be powered on or off, or suspended and resumed as a single object.

The .ctk file. VMware CTK files list any changes made to the VM between backups. This file describes the VMDK block and grows in proportion with the number of VMDK blocks. There is one CTK file per VMDK. Change tracking files originated with VMware's Changed Block Tracking technology for incremental backups. The CTK file stores information about what VM information blocks changed, avoiding unnecessary block backups. VMware snapshots also use .ctk files. Like .log and .nvram files, .ctk files are small.

About the -Defined Data Center
In a software-defined data center, all infrastructure is virtualized, and the control of the data center is entirely automated by software.

vSphere Concepts and Features

VMware vSphere™ leverages the power of virtualization to transform data centers into simplified cloud
computing infrastructures and enables IT organizations to deliver flexible and reliable IT services.
The two core components of vSphere are VMware ESXi™ and VMware vCenter Server®. ESXi is the
virtualization platform on which you create and run virtual machines. vCenter Server is a service that acts as a central administrator for ESXi hosts that are connected on a network. With vCenter Server, you can pool and manage the resources of multiple hosts. vCenter Server provides many features that allow you to monitor and manage your physical and virtual infrastructure.
Additional vSphere components are available as plugins that extend the functionality of the vSphere
product.

Virtualization Basics
A virtual machine is a software computer that, like a physical computer, runs an operating system and applications. The hypervisor serves as a platform for running virtual machines and allows for the consolidation of computing resources.

Each virtual machine contains its own virtual, or software-based, hardware, including a virtual CPU, memory, hard disk, and network interface card.

Software called the hyper-visor is installed on the physical hardware in a virtualized data-center, and acts as a platform for virtual machines.