Virtualization Stuff - Paiet/Tech-Journal-for-Everything GitHub Wiki

What is a Virtual Machine? - software based representation of a physical computer that includes a set of specification and configuration files, and is backed by the physical resources of a host. Virtual Machines allow any application in any OS to run and consume CPU, memory, disk, and network resources from a host.

For the list of all supported operating systems, see:

https://www.vmware.com/resources/compatibility/search.php

What are the benefits if I use a Virtual Machine? -

Easy to move or copy:

-- Encapsulated into files -- Independent of physical hardware

Easy to manage:

-- Isolated from other virtual machines running on same physical hardware -- Insulated from physical hardware changes

CPU Virtualization - When CPU contention occurs, the ESXi host time-slices the physical processors across all virtual machines so that each virtual machine runs as if it had a specified number of virtual processors.

A virtual machine consists of several files that are stored on a storage device. The key files are the configuration file, virtual disk file, NVRAM setting file, and log file. You configure virtual machine settings through the vSphere Client, one of the vSphere command-line interfaces (PowerCLI, vCLI), or the vSphere Web Services SDK.

Virtual Machine Files

File Usage Description

.vmx vmname.vmx VM configuration file

.vmxf vmname.vmxf Additional VM configuration files

.vmdk vmname.vmdk Virtual disk characteristics

-flat.vmdk vmname-flat.vmdk Virtual machine data disk

.nvram vmname.nvram or nvram VM BIOS or EFI configuration

.vmsd vmname.vmsd Virtual machine snapshots

.vmsn vmname.vmsn VM snapshot data file

.vswp vmname.vswp Virtual machine swap file

.vmss vmname.vmss Virtual machine suspend file

.log vmware.log Current virtual machine log file

-#.log vmware-#.log Old virtual machine log files (where # is a number starting with 1)

Additional files are created when you perform certain tasks with the virtual machine:

- The .hlog file is a log file that is used by vCenter Server to keep track of

virtual machine files that must be removed after a certain operation completes

- The .vmtx file is created when you convert a virtual machine to a template.

The .vmtx file replaces the virtual machine configuration file (.vmx file)

Types of Virtualization:

  1. Server virtualization allows multiple guest operating systems to run on a single physical server as virtual machines, each with access to the underlying server's computing resources

  2. Network virtualization is the complete reproduction of a physical network in software.

Using virtual networking, you can link local virtual machines together and link local virtual machines to the external network through a virtual switch. A virtual switch, like a physical Ethernet switch, forwards frames at the data link layer. The virtual switch connects to the external network through outbound Ethernet adapters, called vmnics.

Virtual switches support VLAN segmentation at the port level, so that each port can be configured as an access or trunk port, providing access to either single or multiple VLANs. However, unlike physical switches, virtual switches do not require the Spanning Tree Protocol, because a single-tier networking topology is enforced. Multiple virtual switches cannot be interconnected and network traffic cannot flow directly from one virtual switch to another virtual switch on the same host. Virtual switches do not need to be cascaded because virtual switches do not share physical Ethernet adapters and leaks do not occur between virtual switches.

  1. Storage virtualization creates a software-based representation of network storage devices. Virtual machine files are stored in directories on a VMFS, NFS, VMware vSAN, or VMware vSphere Virtual Volumes datastore.

vSphere 7.0 Configuration Maximums:

https://configmax.vmware.com/guest?vmwareproduct=vSphere&release=vSphere%207.0&categories=1-0

The virtual hardware version determines the operating system functions that a virtual machine supports. Do not use a later version that is not supported by the VMware product.

Compatibility Hardware Version

ESXi 7.0 Update 1 and later 18

ESXi 7.0 and later 17

ESXi 6.7 Update 2 and later 15

ESXi 6.7 and later 14

ESXi 6.5 and later 13

ESXi 6.0 and later 11

ESXi 5.5 and later 10

NOTE: A virtual machine cannot have more virtual CPUs than the number of logical CPUs on the host. The number of logical CPUs is the number of physical processor cores, or twice that number if hyperthreading is enabled.

Virtual Storage Options - ESXi hosts offer several choices in storage adapters to a virtual machine:

- BusLogic Parallel - Latest Mylex BT/KT-958 HBA adapter
- LSI Logic Parallel - LSI Logic LS153C10xx Ultra320 SCSI I/O
- LSI Logic SAS - provides a Serial interface
- VMware Paravirtual SCSI - higher throughput & lower CPU usage
- AHCI SATA controller  - available only to VMs with ESXi 5.5 & later compatibility
- Virtual NVMe  - Intel specification used to attach and use flash storage

via the PCI Express bus

Thick provisioning uses all the defined disk space at the creation of the virtual disk:

- Virtual machine disks consume all the capacity, as defined at creation,

regardless of the amount of data in the guest operating system file system.

Eager-zeroed or lazy-zeroed:

- Every block in an eager-zeroed thick-provisioned disk is prefilled with a zero

- Every block in a lazy-zeroed thick-provisioned disk is filled with a zero

when data is written to the block

Thin provisioning enables virtual machines to use storage space as needed:

- Thin-provisioned virtual machine disks consume only the capacity needed to

hold the current files

- A virtual machine sees the full allocated disk size at all times

Run the unmap command to reclaim unused space from the array. You can mix thick and thin formats.

Types of supported network adapters:

- E1000E: Emulated Intel 82574 Gigabit NIC. Default for Windows 8 & Server 2012

- E1000: Emulated Intel 82545EM Gigabit NIC. Windows XP forward & Linux 2.4.19

forward

- Flexible: The "chameleon" of virtual NICs. Identifies itself as a Vlance

adapter upon boot, but then depending on the driver set that initializes & whether VM tools are installed, it may become a VMXNET adapter

- Vlance: Emulated AMD 79C970 PCnet32 LANCE NIC. Older 10 Mbps with 32-bit

drivers

- VMXNET2 (Enhanced): NOT SUPPORTED for ESXi 6.7 & later

- VMXNET3: Most up to date paravirtualized NIC

- SR-IOV pass-through: VMs and the physical NIC of the host are able to

communicate DIRECTLY, bypassing the VMkernel. Limited by the VMs O/S ability to support it

- VMware vSphere DirectPath I/O: Allows VM access to physical PCI network

functions where there is an I/O memory management unit. If you use this, the following features become unavailable for the VM:

	1\. Hot add or remove of devices
	2. Suspend & resume
	3. Record & replay
	4. Fault Tolerance (FT)
	5. High Availability (HA)
	6. Limited DRS capability - VM can be a member of a cluster, but cannot be migrated across hosts
	7. Snapshots

- PVRDMA (Paravirtualized remote direct memory access): Allows multiple VMs to

access the RDMA device

ESXi - A "Bare-Metal" Hypervisor that can be purchased or used as a free download called the VMware vSphere Hypervisor.

https://www.vmware.com/products/vsphere-hypervisor.html

Can be installed on:

1\. Hard disks
2. SAN LUNs
3. USB devices
4. SD cards
5. SATADOM - a disk on module (DOM) with flash drive and SATA Interface to be

used as a computer hard disk drive (HDD) 6. SSD 7. Diskless Hosts

What is the Security Profile? - Controls remote access to an ESXi Host

ESXi hosts have a built in firewall that is enabled by default and set to block ALL inbound/outbound traffic NOT DEFINED in the security profile.

What is Network Time Protocol (NTP) & why do I care? - used to synchronize a host's clock so that accurate time based system information may be monitored and logged. ESXi hosts can be NTP clients that are set to synchronize from an external NTP server.

http://www.ntp.org

ESXi Quick Boot - enables the host to reboot WITHOUT reinitializing the host's BIOS. Enabled by default on supported hardware. Can be disabled if necessary. Integrated into VMware Update Manager (VUM) workflows for faster upgrades.

Supported on Dell Poweredge & HPE ProLiant