Home > Articles > VMware

  • Print
  • + Share This
This chapter is from the book

vMotion and Storage vMotion

  • vMotion
  • Storage vMotion
  • Eagerzeroed

vMotion is probably the most popular and most sought after feature in the VMware infrastructure suite. The vMotion feature allows a running virtual machine to be migrated without interruption from one host to another, provided that some prerequisites are met on the originating and destination hosts.

Storage vMotion, on the other hand, allows you to migrate a VM's data files from one storage location to another without interruption. The vMotion suite collectively allows you to control a VM's host placement and its data file placement at any time for performance or organization purposes without downtime.

vMotion

vMotion is an enterprise-level feature and thereby requires vCenter before it can be enabled. vMotion, as you see later in the section "Distributed Resource Scheduler," is used in conjunction with DRS to make sure VMs are always spread out on the most appropriate host, thereby balancing the resource availability of these hosts.

vMotion Host Prerequisites

With vMotion, for the VM to successfully port from one host to another, the following requirements must be satisfied on the source and destination hosts:

  • Access to all datastores on which the VM is configured
  • Virtual switches that are labeled the same, so that when the VM is ported from one host to another, its configuration is the same and finds the same resources
  • Access to the same physical networks for the VM to continue to function after being ported from one host to another
  • Compatible CPUs
  • Gigabit network connection

When you initiate a vMotion from one host to another, the wizard that starts the process warns you if there are errors that prevent the migration from completing successfully. The vMotion wizard also provides warnings that you take into account and possibly address after the migration is completed. Warnings do not prevent the vMotion process from completing successfully, whereas errors do. Table 8.2 outlines the different scenarios that might generate an error or a warning.

Table 8.2. vMotion Errors and Warnings

vMotion Errors

vMotion Warnings

A VM is connected to an internal vSwitch on the source host.

A VM is configured for an internal vSwitch but is not connected to it.

A VM has a removable disk such as a CD/DVD-ROM or floppy connected to it.

A VM is configured for a removable CD/DVD-ROM or floppy but is not connected to it.

A VM has CPU affinity assigned.

A VM has a snapshot.

A heartbeat cannot be detected from the VM to be migrated.

Enabling vMotion

To enable vMotion, you need to create a VMkernel port group with vMotion enabled on all ESX/ESXi hosts that will participate in the vMotion process, as shown in Figure 8.3. The virtual switch where this port group is created should bear the same label on all ESX/ESXi hosts. Typically, vMotion is configured on a dedicated virtual switch on all ESX/ESXi hosts.

Figure 8.3

Figure 8.3 Port group with vMotion enabled.

vMotion also requires that the physical NIC that you choose to service the virtual switch where vMotion is enabled should be a Gigabit or higher.

vMotion CPU Requirements

One of the main obstacles to a successful vMotion migration is the CPU; vMotion requires a strict CPU approach, so keep the following guidelines in mind:

  • vMotion does not work across CPU vendors, so if you have an ESX/ESXi host that is running an AMD processor and one that is running an Intel processor, vMotion errors out and does not work.
  • vMotion does not work across CPU families, so you are not able to migrate between a Pentium III and a Pentium 4, for example.
  • Hyperthreading, the number of CPU cores, and the CPU cache sizes are not relevant to vMotion.
  • vMotion does not work across CPUs with different multimedia instructions—for example, a CPU with Streaming SIMD Extensions 2 (SSE2) and a CPU with Streaming SIMD Extensions 3 (SSE3).
  • NX/XD hides or exposes advanced features in the CPU of an ESX Server. In most cases, this hidden feature is controlled by VMware for stability reasons (see Figure 8.4). In the event that the guest operating system requires it, however, the vSphere client exposes this feature in the properties of a VM. If it is enabled, the CPU characteristics of the host and destination must match; if disabled, an occurring mismatch is ignored and vMotion proceeds.
    Figure 8.4

    Figure 8.4 NX/XD feature exposed in vSphere client.

CPU vendors Intel and AMD now offer a technology known as virtualization assist that aids virtualization. Intel has its VT technology, and AMD has its AMD-V technology, both of which are enabled in the BIOS of a computer.

In the presence of these technologies, you can enable the VMs whose operating system supports the virtualization assist technology to improve their performance. To do this, you can right-click the VM in question and click Edit Settings. Click the Options tab, find the Paravirtualization section, and enable it. Figure 8.5 illustrates this process clearly.

Figure 8.5

Figure 8.5 Enabling Paravirtualization.

The vMotion Stages

Because the virtual machine to be vMotioned resides on a datastore that is visible and accessible to both the source and the destination ESX/ESXi host, the only thing that vMotion needs to do is to copy the VM's memory from one host to another. Because the VM's memory resides on the physical memory of the source host, that memory is what needs to be copied. That being said, the two ways to initiate a vMotion are as follows:

  • Select one or more VMs and then right-click and choose Migrate.
  • Simply choose the Change host option.

When the vMotion process begins, the four stages that it goes through are as follows:

  1. Once vMotion is initiated, a memory bitmap is created to track the changes, and the process of copying the physical RAM from one host to another begins.
  2. Quiesce the VM and copy the contents of the memory bitmap. Quiesce can be defined in simpler terms as a cut-over. This is the only time at which the VM is unavailable. This is a short period of time that for the most part is transparent to the user.
  3. The virtual machine on the destination host starts and moves all connectivity to it from the source host to the destination host.
  4. The VM is removed from the source host.

During your monitoring of the vMotion process, you might notice that it pauses at 10% completion as part of the identification process.

Storage vMotion

Storage vMotion is the process of migrating all the VM's files from one storage to another while the VM is powered on and without any interruption. Traditional vMotion moves the logical representation of a VM from one ESX/ESXi host to another while it is powered on while keeping the files that constitute this VM in the same storage space. Storage vMotion complements this by allowing you to move the VM files as well thereby contributing to a complete VM migration from one location to another without an interruption in service.

Storage vMotion was introduced in Virtual Infrastructure 3.5 but only at the command-line level; with vSphere 4, you can now do Storage vMotion from a GUI. To initiate a Storage vMotion from the GUI you follow the same steps as you would for a normal vMotion, which is to right-click a VM and select Migrate. The difference is the screen shown in Figure 8.6 has been completely changed with the following options:

  • Change Host: This is obviously the traditional vMotion option, which moves the VM while it is powered on or off from one ESX/ESXi host to another.
  • Change Datastore: This is the option to do a Storage vMotion thereby moving all the VM's files from one storage to another while the VM is powered on or off.
  • Change Both Host and Datastore: As the name implies you can move both the VM and its corresponding files from one host to another with one catch, the VM has to be powered off.
Figure 8.6

Figure 8.6 Migrate Wizard.

The next screen shown in Figure 8.7 prompts you to select the destination datastore where you want to move the files to. It is important to note that with vSphere 4 all protocols are now supported, which means, iSCSI, Fiber Channel, Fiber Channel over Ethernet (FCoE), NFS, and RDMs.

Figure 8.7

Figure 8.7 Datastore destination.

This brings us to the last step in the Storage vMotion wizard, which is the disk format. While Storage vMotion is primarily used to move VM files from one storage to another you might find this tool useful to change the disk format from Thin to Thick or vice versa. In Figure 8.8, note two options for disk type: Thin and Thick. The important thing to note here is that the reference to Thick is the Eagerzeroedthick, which means that the VMDK will be zeroed, thus thin provisioning will not be possible once this is converted to this type of Thick.

Figure 8.8

Figure 8.8 Disk format type.

Cram Quiz

Answer these questions. The answers follow the last question. If you cannot answer these questions correctly, consider reading the section again.

  1. Storage vMotion and vMotion can be run simultaneously while_______.

    bullet.jpg

    A.

    The VM is powered on.

    bullet.jpg

    B.

    The VM is powered off.

    bullet.jpg

    C.

    The VM is powered on or off.

    bullet.jpg

    D.

    They cannot be run simultaneously under any circumstance.

  2. Which virtual disk type writes zeros across all the capacity of the virtual disk?

    bullet.jpg

    A.

    Eagerzeroed

    bullet.jpg

    B.

    Eagerzeroedthick

    bullet.jpg

    C.

    Zeroedthick

    bullet.jpg

    D.

    Thick

Cram Quiz Answers

  1. B is correct. You cannot run Storage vMotion and vMotion simultaneously while the VM is powered on. You can run them while the VM is powered off, or you can schedule them to run consecutively.

  2. B is correct. Eagerzeroedthick is the virtual disk type that writes zeroes across the entire capacity of the disk and commits it all, thereby thin provisioning would not be possible. All other types are incorrect.

  • + Share This
  • 🔖 Save To Your Account

Pearson IT Certification Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Pearson IT Certification and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Pearson IT Certification products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.pearsonitcertification.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020