Configuring Virtual Machine Storage

Creating and Configuring Virtual Machine Storage

• Virtual hard disk (VHD) format allows part of a physical disk to appear as a physical hard drive to a VM.

Virtual Hard Disk (VHD) Formats

• Fixed hard disk image: allocates the entire space allotted to it during VM creation.
• Dynamic hard disk image: can hold various volume types (simple, spanned, mirrored, striped, RAID-5) and may consist of several physical disks.
• Differencing hard disk image: stores changes made to another VHD or the guest operating system.

Virtual Hard Disk (VHD) and Virtual Hard Disk (VHDX) Comparison

• VHD:
  • Limited to 2 TB
  • Compatible with all versions of Hyper-V, Virtual Server, and Virtual PC
• VHDX:
  • Up to 64 TB
  • Supports 4 KB logical sector size
  • Not backwards compatible

Creating a Virtual Hard Disk using the New Virtual Machine Wizard

• The wizard includes a Connect Virtual Hard Disk page that allows adding a single disk to a new VM with three options:
  • Create a virtual hard disk: specifies name, location, and size of a new virtual hard disk (only creates dynamically expanding VHDX disk).
  • Use an existing virtual hard disk: specifies location of an existing VHD or VHDX disk.
  • Attach a virtual hard disk later: prevents the wizard from adding virtual disks to the VM configuration, assuming addition will be done manually before starting the VM.

Pass-through Disk

• Also known as directly attached disks, allowing a VM direct access to underlying storage rather than a virtual hard disk.

Snapshot

• A captured image of a VM's state, data, and hardware configuration at a particular moment in time.

DHCP Service

• Automatically configures IP address and other TCP/IP settings on network computers
• Assigns addresses from a pool (called a scope) and reclaims them when no longer in use

DHCP Components

• DHCP server application: responds to client requests for TCP/IP configuration settings
• DHCP client: issues requests to servers and applies received TCP/IP configuration settings
• DHCP communications protocol: defines formats and sequences of messages exchanged between clients and servers

IP Address Allocation Methods

• Dynamic allocation: assigns memory space during execution time
• Automatic allocation: server administrator creates a configuration with IP addresses for clients
• Manual allocation: a particular IP address is pre-allocated to a single device by an administrator

DHCP Extensions

• Provide parameters for DHCP lease negotiation and renewal processes
• Options include:
  • Requested IP Address
  • IP Address Lease Time
  • Server Identifier
  • Parameter Request List
  • Message
  • Renewal (T1) time value
  • Rebinding (T2) time value

DHCP Message Types

• DHCPDISCOVER
• DHCPOFFER
• DHCPREQUEST
• DHCPDECLINE
• DHCPACK
• DHCPNAK
• DHCPRELEASE
• DHCPINFORM

Configuring DHCP Options

• Windows DHCP server supports two kinds of options:
  • Scope options: supplied only to clients receiving addresses from a particular scope
  • Server options: supplied to all clients receiving addresses from the server
• Reservation: a manually allocated address