Browse Definitions :
Definition

differencing disk

Contributor(s): Anil Desai

A differencing disk is a virtual hard disk (VHD) that stores changes made to another VHD or to the guest operating system. The purpose of differencing disks is to make it possible to maintain information about changes made so that they can be reversed if necessary.

Differencing disks are based on either a fixed-size or dynamically expanding VHD and can be configured with parent-child relationships to form a hierarchy of VHD types. The disks store all of the changes that would otherwise be written to the parent VHD.  However, it's important to remember that, as a rule, any VHD that serves as a parent must remain read-only.

Differencing disks can increase manageability, especially when multiple VMs share a similar configuration, and can dramatically reduce the amount of disk space required on a Virtual Server host computer. The drawbacks are that differencing disks can be difficult to manage and large hierarchies of disks can potentially lead to performance problems, especially if all of the physical VHD files are located on the same disks or arrays. Within Virtual Server, you can merge a differencing disk with its parent -- an operation that commits all the changes and either updates the base VHD or creates a new VHD file.

This was last updated in April 2013

Continue Reading About differencing disk

Join the conversation

1 comment

Send me notifications when other members comment.

Please create a username to comment.

Some Queries:

1. What happens to child VMs if parent disk got corrupted.
2. Can we replace parent disk with another parent disk?
3. If I make 1000 child VMs from 1 parent disk, does it have IO issues or bottlenecks?
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

  • compliance framework

    A compliance framework is a structured set of guidelines that details an organization's processes for maintaining accordance with...

  • regulatory compliance

    Regulatory compliance is an organization's adherence to laws, regulations, guidelines and specifications relevant to its business...

  • privacy compliance

    Privacy compliance is a company's accordance with established personal information protection guidelines, specifications or ...

SearchSecurity

SearchHealthIT

  • telemedicine (telehealth)

    Telemedicine is the remote delivery of healthcare services, such as health assessments or consultations, over the ...

  • Project Nightingale

    Project Nightingale is a controversial partnership between Google and Ascension, the second largest health system in the United ...

  • medical practice management (MPM) software

    Medical practice management (MPM) software is a collection of computerized services used by healthcare professionals and ...

SearchDisasterRecovery

  • crisis management plan (CMP)

    A crisis management plan (CMP) outlines how to respond to a critical situation that would negatively affect an organization's ...

  • disaster recovery (DR) test

    A disaster recovery test (DR test) is the examination of each step in a disaster recovery plan as outlined in an organization's ...

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

SearchStorage

  • kilobyte (KB or Kbyte)

    A kilobyte (KB or Kbyte) is a unit of measurement for computer memory or data storage used by mathematics and computer science ...

  • megabytes per second (MBps)

    Megabytes per second (MBps) is a unit of measurement for data transfer speed to and from a computer storage device.

  • zettabyte

    A zettabyte is a unit of measurement used by technology professionals and the general public to describe a computer or other ...

Close