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Webcast: “Understanding and Managing VM Sprawl”

Dec 1

Posted by Anil Desai in Best Practices, Management, Policies, Presentations, Security, Virtualization, Webcasts | No Comments

The idea of virtual machine “sprawl” – the rapid proliferation of VMs without adequate IT oversight or management – seems to be a popular one.  I have written and spoken on this topic before, but there have been enough changes in the tools and implementation methods for server virtualization to merit an updated presentation.  That’s the topic of a recent webcast that I recorded for TechTarget’s SearchCIO.com site. 

The webcast is titled “Understanding and Managing VM Sprawl”.  An archived version is available for viewing at no cost (though registration is required).  Here’s a brief abstract of the topic:

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Virtualization can help address many of IT’s biggest headaches, but it can also lead to a problem known as "VM sprawl" – the rapid proliferation of VMs without sufficient IT oversight.  The result is an environment that doesn’t meet security or administration requirements, putting applications, services, and data at risk.

This webcast will provide an overview of VM sprawl – its root causes and related issues, along with ways to mitigate the main issues.  Specifically, it will provide best practices for managing the entire virtual machine life cycle (from deployment to retirement) and details related to tracking VMs in the environment.  The webcast will then describe how automated virtualization management solutions can help provide all of the benefits of virtualization with minimum administrative overhead.

The content is targeted towards IT managers and higher-level IT people.  It focuses on virtualization management strategies, though there’s a good amount of technical depth.  The presentation is roughly 45 minutes in length.  I hope you find it useful, and feel free to post questions or comments here.

Microsoft Virtual Event: The New Efficiency

Oct 23

Posted by Anil Desai in Best Practices, Presentations, Virtualization, Webcasts, Windows 7, Windows Server | No Comments

If you’ve been following some of the latest keynotes and presentations from Microsoft, you’ve probably run into the theme of “The New Efficiency”.  Microsoft has been using this term to describe the benefits of Windows 7, Windows Server 2008 R2 and Exchange Server 2010.  While listening to presentations can be useful, it’s also valuable to spend some interactive time with other technical professionals and experts.  To that end, Microsoft is hosting another live “Virtual Conference” on October 27, 2009.  Visit the Event Overview page to see details of the virtual conference.  Here’s an excerpt that describes what’s covered and who will be presenting:

Join renowned Microsoft technologies expert Paul Thurrott, Windows IT Pro senior technical director Michael Otey, Exchange guru Paul Robichaux, and Windows IT Pro editor in chief Jeff James for an in-depth, spin-free deep dive into the new efficiency.
In just three hours, directly from your own computer, the keynote and three technical sessions will provide you with:

  • an overview of everything that Windows® 7 has to offer
  • a deep-dive into enterprise-oriented features such as AppLocker, Branche Cache, DirectAccess, federated search, and BitLocker to Go
  • a complete coverage of all of the new features and functionality brought by Windows® Server 2008 R2, including Hyper-V virtualization with live migration and PowerShell 2.0
  • an in-depth presentation of the rich user experience, the many deployment options, and information protection and control capabilities offered by Microsoft® Exchange Server 2010
  • a clear understanding of the ways Windows® 7, Windows® Server 2008 R2, and Microsoft® Exchange Server 2010 work better together

This event is presented in an interactive, real-life simulation! You will experience a lifelike visual environment, networking and interactive tools, staffed sponsor booths, and educational chats to complement each conference session.

I’ll be available to answer technical questions in the Microsoft booth during the morning sessions (from 9:30am to around noon Central time).  Feel free to stop by and ask questions or view the materials and presentations that are available online.

For more details, see the Agenda and Speaker Info pages.  Be sure to Register – it’s free, and you don’t have to leave the comfort of your home or office to attend. 

Best Practices to Prevent and Manage Virtual Machine Sprawl (White Paper)

Jul 1

Posted by Anil Desai in Articles, Best Practices, Management, Virtualization | No Comments

Sun-manage_vm_sprawlOften, new technology tends to bring with it some new problems that need to be addressed.  Granted, the problems are “better” ones to have, but they’re important concerns nonetheless.  Server virtualization is no exception.

It’s somewhat ironic that one of the main problems that server virtualization is designed to address, server sprawl, is often replaced with a similar problem – VM sprawl.  It’s a topic that I’ve written a lot about in the past and on this blog.  I recently revisited the topic and expanded on it in a White Paper that I wrote for Sun.  Here’s the introduction from Best Practices to Prevent and Manage Virtual Machine Sprawl:

While server consolidation using virtualization can significantly decrease costs and improve efficiency, organizations often find that they need to deal with an associated issue: the rapid proliferation of VMs with inadequate management. This article will provide best practices for addressing the issue of "VM Sprawl", including the following:

  • Creating and enforcing deployment policies
  • Detecting and addressing unauthorized VMs
  • Managing security and compliance in virtual environments
  • Managing the entire VM lifecycle and Planning for VM retirement
  • Sidebar: Steps to gaining (or regaining) control of a virtual environment.

The White Paper is available for free, but registration on the Sun Web site is required.

Hyper-V in Review: Strengths and Drawbacks

Sep 8

Posted by Anil Desai in Best Practices, Microsoft Hyper-V, Virtualization | No Comments

It has been several months since Microsoft’s Hyper-V has become officially available.  Since then, there have been some twists and variations, including a dedicated Hyper-V Server product that doesn’t require any Windows Server licenses (I’ll write about that sometime in the future).  It seemed like a good time to take a small step back and re-assess the state of Hyper-V.  In the early days, there was no shortage of fear, uncertainty, and doubt (FUD) being cast at the product.  Just a few months later, most experts seem to agree that Hyper-V is ready for the Enterprise and is a perfectly-viable option for data center deployments.

My recent SearchServerVirtualization.com article, Assessing Hyper-V’s Benefits, limitations looks at some of the details.  From the article’s introduction:

Earlier this year, the letters "ESX" were synonymous with server virtualization and VMware seemed to be the only practical game in town. It has now been a few months since a stealthy little software behemoth from the Pacific Northwest released its serious virtualization contender. And in that time, things have changed. In this tip, I’ll highlight some of the post-release considerations for Hyper-V.

Hyper-V’s strengths and weaknesses
Hyper-V’s primary strength is probably its ready availability in the data center. If you’re running Windows Server 2008 on 64-bit hardware, you’re just minutes away from enabling an industrial-strength Hypervisor. Hyper-V’s management tools should be familiar to anyone who manages Windows systems, and the last few months have shown that it is a stable and reliable option for the data center.

Of course, Hyper-V is not without its limitations. Virtualization experts are quick to point out that it doesn’t support live migration of VMs between servers and doesn’t allow administrators to over-commit memory (VMware provides both features). But, Hyper-V provides numerous options based on clustering, so building highly-available Hyper-V deployments is possible and supported. Users of this new product on the enterprise virtualization scene will need some time before completely trusting this candidate over the incumbents.

The full article is available for free and provides details related to support policies, and technical pros and cons of Microsoft’s latest virtualization product.

Optimizing Hyper-V Performance

Jul 28

Posted by Anil Desai in Best Practices, Management, Microsoft Hyper-V, Virtualization | No Comments

If you’re in touch with your geeky side, there’s a good chance that you’re always looking for ways to squeeze more performance out of your IT investments.  This is especially true for situations that involve virtualization, where some of the primary motivation is reducing costs through server consolidation. 

I have recently written two articles for SearchServerVirtualization.com that cover the  topic of monitoring and optimizing your VMs that are hosted on Microsoft Hyper-V.  Some might be obvious, but others are somewhat cleverly-disguised.  The first article, Optimizing Hyper-V performance: Monitoring tips focuses on ways in which you can make sure your host servers and VMs are running smoothly.  From the introduction:

How can you be sure whether your Hyper-V host servers and virtual machines (VMs) have been optimally configured? Installing and enabling Microsoft Hyper-V and creating VMs is a fairly straightforward process; but the techie tendencies in all of us seems to nag the question "Isn’t there something more I should do to improve performance?" This tip targets system administrators who have deployed Hyper-V and want to ensure that they’ve made the most of host servers and VMs.

The second article, Optimizing Hyper-V performance: Advanced fine-tuning provides details on Integration Services, synthetic vs. emulated drivers, and ways in which you can improve overall performance of storage and network resources.

I hope these articles will serve as a useful checklist for Hyper-V management.  If you have any further suggestions, feel free to leave them as comments here or on SearchServerVirtualization.com.

Evaluating Virtualization Management Solutions: Free eBook Chapter

Jan 11

Posted by Anil Desai in Best Practices, Management | 1 Comment

The tenth and final chapter of my eBook, the Definitive Guide to Virtual Platform Management is now available for free download (registration is required).  The complete eBook, available as a single PDF, should be available sometime in the near future.  The chapter focuses on details that IT professionals should keep in mind when looking for tools to manage virtualization.  From the introduction:

IT organizations are often aware of the fact that costs associated with managing new technology can far outweigh the initial deployment costs. Virtualization is no exception. Although the ability to run multiple isolated workloads on the same hardware can provide immediate cost savings and benefits throughout the environment, the associated administration tasks involve significant time and effort.

Throughout the previous chapters, I have covered a wide array of practices and recommendations for gaining and retaining control over virtualized environments. The primary challenge is that properly managing an environment that contains dozens (if not hundreds) of virtual machines can be very difficult. When these tasks are performed manually, IT organizations must absorb significant costs.

Fortunately, there’s a better way—through the use of virtualization-aware enterprise automation solutions much of the work can be simplified or even eliminated. With the proliferation of virtual machine technology, literally dozens of products are available for meeting these needs. The focus of this chapter is on presenting factors that should be considered when evaluating these solutions. I’ll present details related to the overall goals of virtualization management, along with specific features IT organizations should look for in products that will help manage their mixed virtual and physical infrastructures.

I hope readers find the entire guide to be useful.  Feel free to leave questions and comments here.

Virtual Strategy Magazine: Comparing Virtualization Approaches

Dec 20

Posted by Anil Desai in Best Practices, Management, Systems Admin, Virtualization | No Comments

Virtual Strategy Magazine has published my latest article: Comparing Virtualization Approaches. The article examines the various approaches to virtualization, including presentation-, application-, and server/hardware-level virtualization.  The following diagram provides a brief overview of the approaches and their details.

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The overall idea is that organizations have a wide array of choices in deciding how to isolate and consolidate their workloads.  The challenges is picking the right tool for the job.

Virtual Platform Management – Data Center Automation

Dec 4

Posted by Anil Desai in Automating / Scripting, Best Practices, Management | No Comments

A new chapter from my eBook titled The Definitive Guide to Virtual Platform Management is now available for free download (registration is required).  Chapter #9, "Data Center Automation", focuses on ways in which enterprise management tools can help make the seemingly insurmountable task of managing server sprawl and VM sprawl much easier.  Here’s a brief excerpt from the introduction:

A constant challenge in most IT environments is that of finding enough time and resources to finish all the tasks that need to be completed. IT departments find themselves constantly fighting fires and responding to a seemingly never-ending stream of change requests. Although virtualization technology can provide numerous advantages, there are also associated management-related challenges that must be addressed. When these tasks are performed manually, the added overhead can reduce cost savings and can result in negative effects on performance, availability, reliability, and security.

In previous chapters, I have covered a broad array of best practices related to virtualization management. Organizations have the ability to choose from a range of implementation methods, including physical servers, virtual machines, and clustered systems. The tasks have ranged from deployment and provisioning to monitoring virtual systems once they are in production. All of this raises questions related to the best method of actually implementing these best practices.

The focus of this chapter is on data center automation. Organizations that have deployed virtual machines throughout their environment can benefit from using enterprise software that has been designed to provide automated control. The goal is to implement technology that can provide for a seamless, self-managing, and adaptive infrastructure while minimizing manual effort. It’s a tall order, but certainly one that is achievable by using a combination of best practices and the right tools.

Stay tuned for the next and final chapter of the Guide!

Microsoft Infrastructure Planning and Design (IPD) Guides Available

Nov 13

Posted by Anil Desai in Best Practices, Microsoft Hyper-V, Microsoft Virtual Server | 1 Comment

I recently worked with Microsoft’s Solution Accelerator team to develop a guide to designing an infrastructure to support Microsoft’s virtualization solutions.  Unlike much of the other technical information that is available online, this series focuses on the design aspect of managing technology, rather than on implementation details.  From the web site:

Infrastructure Planning and Design guides share a common structure, including:

  • Definition of the technical decision flow through the planning process.
  • Listing of decisions to be made and the commonly available options and considerations.
  • Relating the decisions and options to the business in terms of cost, complexity, and other characteristics.
  • Framing decisions in terms of additional questions to the business to ensure a comprehensive alignment with the appropriate business landscape.

These guides complement product documentation by focusing on infrastructure design options.

Each guide leads the reader through critical infrastructure design decisions, in the appropriate order, evaluating the available options for each decision against its impact on critical characteristics of the infrastructure. The IPD Series highlights when service and infrastructure goals should be validated with the organization and provides additional questions that should be asked of service stakeholders and decision makers.

You can download the files from the Infrastructure Planning and Design page (registration is optional).  The content includes the following downloads:

  • IPD Series Introduction: A brief introduction to the series and its approach.
  • Select the Right Virtualization Solution: This guide includes an overview of Microsoft’s virtualization products and technologies.  The package includes a flowchart that can be helpful in deciding how to select from among Microsoft Virtual Server 2005, Microsoft Virtual PC, Microsoft Terminal Services, Microsoft SoftGrid, and the newly-announced Hyper-V (available with Windows Server 2008).
  • Windows Server Virtualization: This guide covers details on Windows Server Virtualization (WSv, now officially "Hyper-V") and Microsoft Virtual Server.  It includes a document and slides that cover the process of selecting which workloads to virtualize.  The guide then walks through the process of translating virtual machine requirements to host infrastructure requirements.
  • SoftGrid Application Virtualization: This guide focuses on SoftGrid – recently renamed to Microsoft Application Virtualization.  It covers best practices for designing an infrastructure for simplified application deployment and maintenance.

All downloads include files in Office 2003 and Office 2007 formats and are ready for use in your own presentations or proposals.  More guides will be available in the near future, and you should be able to access beta versions of upcoming guides at Microsoft Connect.  I hope you find the content to be useful!

Virtual Platform Management: Policies and Processes

Nov 7

Posted by Anil Desai in Best Practices, Management, Policies | No Comments

DGVPM Cover Chapter #8 of my free eBook called, The Definitive Guide to Virtual Platform Management, is now available for download.  This chapter talks about ways in which organizations can use policies and processes to better manage virtualization.  Included is information about creating and enforcing Service Level Agreements (SLAs), implementing charge-backs, and other best practices.  Check it out online (and don’t miss the first seven chapters)!

IT Fights Back: Virtualization SLAs and Charge-Backs

Oct 27

Posted by Anil Desai in Best Practices, Management, Policies | No Comments

My article, the first in a series entitled, “Fighting The Dark Side of Virtualization” is now available on the Virtual Strategy Magazine Web site.  The article, IT Fights Back: Virtualization SLAs and Charge-Backs, focuses on ways in which IT departments can help manage issues such as VM sprawl (the explosive proliferation of VMs), while containing costs.  As a quick teaser, here’s the opening marquee:

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The adventure begins…

Managing Virtualization Storage for Datacenter Managers

Oct 21

Posted by Anil Desai in Best Practices, Management, Storage | No Comments

This article was first published on SearchServerVirtualization.TechTarget.com.

Deploying virtualization into a production data center can provide an interesting mix of pros and cons. By consolidating workloads onto fewer server, physical management is simplified. But what about managing the VMs? While storage solutions can provide much-needed flexibility, it’s still up to datacenter administrators to determine their needs and develop appropriate solutions. In this article, I’ll present storage-related considerations for datacenter administrators.

Estimating Storage Capacity Requirements

Virtual machines generally require a large amount of storage. The good news is that this can, in some cases, improve storage utilization. Since direct-attached storage is not confined to a per-server basis (which often results in a lot of unused space), using centralized storage arrays can help. There’s also a countering effect, however: Since the expansion of virtual disk files is difficult to predict, you’ll need to leave some unallocated space for expansion. Storage solutions that provide for over-committing space (sometimes referred to as “soft-allocation”) and for dynamically resizing arrays can significantly simplify management.

  • To add up the storage requirements, you should consider the following:
  • The sum of the sizes of all “live” virtual disk files
  • Expansion predictions for virtual disk files
  • State-related disk files such as those used for suspending virtual machines and maintaining point-in-time snapshots
  • Space required for backups of virtual machines

All of this can be a tall order, but hopefully the overall configuration is no more complicated than that of managing multiple physical machines.

Placing Virtual Workloads

One of the best ways to reduce disk contention and improve overall performance is to profile virtual workloads to determine their requirements. Performance statistics help determine the number, size, and type of IO operations. Table 1 provides an example.

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Table 1: Assigning workloads to storage arrays based on their performance requirements

In the provided example, the VMs are assigned to separate storage arrays to minimize contention. By combining VMs with “compatible” storage requirements on the same server, administrators can better distribute load and increase scalability.

Selecting Storage Methods

When planning to deploy new virtual machines, datacenter administrators have several different options. The first is to use local server storage. Fault-tolerant disk arrays that are directly-attached to a physical server can be easy to configure. For smaller virtualization deployments, this approach makes sense. However, when capacity and performance requirements grow, adding more physical disks to each server can lead to management problems. For example, arrays are typically managed independently, leading to wasted disk space and requiring administrative effort.

That’s where network-based storage comes in. By using centralized, network-based storage arrays, organizations can support many host servers using the same infrastructure. While support for technologies varies based on the virtualization platform, NAS, iSCSI, and SAN-based storage are the most common. NAS devices use block-level IO and are typically used as file servers. They can be used to store VM configuration and hard disk files. However, latency and competition for physical disk resources can be significant.

SAN and iSCSI storage solutions perform block-level IO operations, providing raw access to storage resources. Through the use of redundant connections and multi-pathing, they can provide the highest levels of performance, lowest latency, and simplified management.

In order to determine the most appropriate option, datacenter managers should consider workload requirements for each host server and its associated guest OS’s. Details include the number and types of applications that will be running, and their storage and performance requirements. The sum of this information can help determine whether local or network-based storage is most appropriate.

Monitoring Storage Resources

CPU and memory-related statistics are often monitoring for all physical and virtual workloads. In addition to this information, disk-related performance should be measured. Statistics collected at the host server level will provide an aggregate view of disk activity and whether storage resources are meeting requirements. Guest-level monitoring can help administrators drill-down into the details of which workloads are generating the most activity. While the specific statistics that can be collected will vary across operating systems the types of information that should be monitoring include:

  • IO per Second (IOPs): This statistic refers to the number of disk-related transactions that are occurring at a given instant. IOPs are often used as the first guideline for determining overall storage requirements.
  • Storage IO Utilization: This statistic refers to the percentage of total IO bandwidth that is being consumed at a given point in time. High levels of utilization can indicate the need to upgrade or move VMs.
  • Paging operations: Memory-starved VMs can generate significant IO traffic due to paging to disk. Adding or reconfiguring memory settings can help improve performance.
  • Disk queue length: The number of IO operations that are pending. A consistently high number will indicate that storage resources are creating a performance bottleneck.
  • Storage Allocation: Ideally, administrators will be able to monitor the current amount of physical storage space that is actually in use for all virtual hard disks. The goal is to proactively rearrange or reconfigure VMs to avoid over-allocation.

VM disk-related statistics will change over time. Therefore, the use of automated monitoring tools that can generate reports and alerts are an important component of any virtualizations storage environment.

Summary

Managing storage capacity and performance should be high on the list of responsibilities for datacenter administrators. Virtual machines can easily be constrained by disk-related bottlenecks, causing slow response times or even downtime. By making smart VM placement decisions and monitoring storage resources, many of these potential bottlenecks can be overcome. Above all, it’s important for datacenter administrators to work together with storage managers to ensure that business and technical goals remain aligned over time.

Virtualization Considerations for Storage Managers

Oct 20

Posted by Anil Desai in Best Practices, Management, Storage | No Comments

This article was first published on SearchServerVirtualization.TechTarget.com.

It’s common for new technology to require changes in all areas of an organization’s overall infrastructure. Virtualization is no exception. While many administrators often focus on CPU and memory constraints, storage-related performance is also a very common bottleneck. In some ways, virtual machines can be managed like physical ones. After all, each VM runs its own operating systems, applications, and services. But there are also numerous additional considerations that must be taken into account when designing a storage infrastructure. By understanding the unique needs of virtual machines, storage managers can build a reliable and scalable data center infrastructure to support their VMs.

Analyzing Disk Performance Requirements

For many types of applications, the primary consideration around which the storage infrastructure is designed is based on I/O operations per second (IOPS). IOPS refer to the number of read and write operations that are performed, but do not always capture the whole picture. Additional considerations include the type of activity. For example, since virtual disks that are stored on network-based storage arrays must support guest OS disk activity, the average I/O request size tends to be small. Additionally, I/O requests are frequent and often random in nature. Paging can also create a lot of traffic on memory-constrained host servers. There are also other considerations that will be workload-specific. For example, it’s also good to measure the percentage of read vs. write operations when designing the infrastructure.

Now, multiply all of these statistics by the number of VMs that are being supported on a single storage device, and you are faced with the very real potential for large traffic jams. The solution? Optimize the storage solution for supporting many, small, and non-sequential IO operations. And, most importantly, distribute VMs based on their levels and types of disk utilization. Performance monitoring can help generate the information you need.

Considering Network-Based Storage Approaches

Many environments already use a combination of NAS, SAN, and iSCSI-based store to support their physical servers. These methods can still be used for hosting virtual machines, as most virtualization platforms provide support for them. For example, SAN- or iSCSI-based volumes that are attached to a physical host server can be used to store virtual machine configuration files, virtual hard disks, and related data. It is important to note that, by default, the storage is attached to the host and not to the guest VM. Storage managers should keep track of which VMs reside on which physical volumes for backup and management purposes.

In addition to providing storage at the host-level, guest operating systems (depending on their capabilities) can take advantage of NAS and iSCSI-based storage. With this approach, VMs can directly connect to network-based storage. A potential drawback, however, is that guest operating systems can be very sensitive to latency, and even relatively small delays can lead to guest OS crashes or file system corruption.

Evaluating Useful Storage Features

As organizations place multiple mission-critical workloads on the same servers through the use of virtualization, they can use various storage features to improve reliability, availability and performance. Implementing RAID-based striping across arrays of many disks can help significantly improve performance. The array’s block size should be matched to the most common size of I/O operations. However, more disks means more chances for failures. So, features such as multiple parity drives and hot standby drives are a must.

Fault tolerance can be implemented through the use of multi-pathing for storage connections. For NAS and iSCSI solutions, storage managers should look into having multiple physical network connections and implementing fail-over and load-balancing features by using network adapter teaming. Finally, it’s a good idea for host servers to have dedicated network connections to their storage arrays. While you can often get by with shared connections in low-utilization scenarios, the load placed by virtual machines can be significant and can increase latency.

Planning for Backups

Storage administrators will have the need to backup many of their virtual machines. Apart from allocating the necessary storage space, it is necessary to develop a method for dealing with exclusively-locked virtual disk files. There are two main approaches:

  • Guest-Level Backups: In this approach, VMs are treated like physical machines. Generally, you would install backup agents within VMs, define backup sources and destinations, and then let them go to work. The benefit of this approach is that only important data is backed up (thereby reducing required storage space). However, your backup solution must be able to support all potential guest OS’s and versions. And, the complete recovery process can involve many steps, including reinstalling and reconfiguring the guest OS.
  • Host-Level Backups: Virtual machines are conveniently packaged into a few important files. Generally, this includes the VM configuration file and virtual disks. You can simply copy these files to another location. The most compatible approach involves stopping or pausing the VM, copying the necessary files, and then restarting the VM. The issue, however, is that this can require downtime. Numerous first- and third-party solutions are able to backup VMs while they’re “hot”, thereby eliminating service interruptions. Regardless of the method used, replacing a failed or lost VM is easy – simple restore the necessary files to the same or another host server and you should be ready to go. The biggest drawback of host-level backups is in the area of storage requirements. You’re going to be allocating a ton of space for the guest OS’s, applications, and data you’ll be storing.

Storage solutions options such as the ability to perform snapshot-based backups can be useful. However, storage administrators should thoroughly test the solution and should look for explicitly-stated virtualization support from their vendors. Remember, backups must be consistent to a point in time, and non-virtualization-aware solutions might neglect to flush information stored in the guest OS’s cache.

Summary

By understanding and planning for the storage-related needs of virtual machines, storage administrators can help their virtual environments scale and keep pace with demand. While some of the requirements are somewhat new, many involve utilizing the same storage best practices that are used for physical machines. Overall, it’s important to measure performance statistics and to consider storage space and performance when designing a storage infrastructure for VMs.

Advanced Backup Options for Virtual Machines

Oct 3

Posted by Anil Desai in Backup / Disaster Recovery, Best Practices, Management | 2 Comments

This article was first published on SearchServerVirtualization.TechTarget.com.

It’s a pretty big challenge to support dozens or hundreds of separate virtual machines. Add in the requirement for backups – something that generally goes without saying – and you have to figure out how to protect important information. Yes, that usually means at least two copies of each of these storage hogs. I understand that you’re not made of storage (unless, of course, you’re the disk array that’s reading this article on the web server). So what should you do? In this tip, I’ll outline several approaches to performing backups for VMs, focusing on the strengths and limitations of each.

Determining Backup Requirements

Let’s start by considering the requirements for performing backups. The list of gaols is pretty simple, in theory:

  • Minimize data loss
  • Minimize recovery time
  • Simplify implementation and administration
  • Minimize costs and resource usage

Unfortunately, some of these objectives are often at odds with each other. Since implementing any solution takes time and effort, start by characterizing the requirements for each of your virtual machines and the applications and services they support. Be sure to write in pencil, as it’s likely that you’ll be revising these requirements. Next, let’s take a look at the different options for meeting these goals.

Application-Level Backups

The first option to consider for performing backups is that of using application features to do the job. There’s usually nothing virtualization-specific about this approach. Examples include:

  • Relational Database Servers: Databases were designed to be highly-available and it should come as no surprise that there are many ways of using built-in backup methods. In addition to standard backup and restore operations, you can use replication, log-shipping, clustering, and other methods to ensure that data remains protected.
  • Messaging Servers: Communications platforms such as Microsoft Exchange Server provide methods for keeping multiple copies of the data store in sync. Apart from improving performance (by placing data closer to those who need it), this can provide adequate backup functionality.
  • Web Servers: The important content for a web server can be stored in a shared location or can be copied to each node in a web server farm. When a web server fails, just restore the important data to a standby VM, and you’re ready to go. Better yet, use shared session state or stateless application features and a network load-balancer to increase availability and performance.

All of these methods allow you to protect against data loss and downtime by storing multiple copies of important information.

Guest-Level Backups

What’s so special about VMs, anyway? I mean, why not just treat them like the physical machines that they think they are? That’s exactly the approach with guest-level backups. The most common method with this approach is to install backup agents within the guest OS and to specify which files should be backed up and their destinations. As with physical servers, administrators can decide what really needs to be backed up – generally just data, applications, and configuration files. That saves precious disk space and can reduce backup times.

There are, however, drawbacks to this backup approach. First, your enterprise backup solution must support your guest OS’s (try finding an agent for OS/2!) Assuming the guest OS is supported, the backup and recovery process is often different for each OS. This means more work on the restore side of things. Finally, the restore process can take significant time, since a base OS must be installed and the associated components restored.

Examples of popular enterprise storage and backup solutions are those from Symantec, EMC, Microsoft and many other vendors.

Host-Level Backups

Host-level backups take advantage of the fact that virtual machines are encapsulated in one or more virtual disk files, along with associated configuration files. The backup process consists of making a copy of the necessary files from the host OS’s file system. Host-level backups provide a consistent method for copying VMs since you don’t have to worry about differences in guest operating systems. When it comes time to restore a VM (and you know it’s going to happen!), all that’s usually needed is to reattach the VM to a working host server.

However, the drawback is that you’re likely to need a lot of disk space. Since the entire VM, including the operating system, applications, and other data are included in the backup set, you’ll have to allocate the necessary storage resources. And, you’ll need adequate bandwidth to get the backups to their destination. Since virtual disk files are exclusively locked while a VM is running, you’ll either need to use a “hot backup” solution, or you’ll have to pause or stop the VM to perform a backup. The latter option results in (gulp!) scheduled downtime.

Solutions and technologies include:

  • VMware: VMotion; High Availability; Consolidated Backup; DRS
  • Microsoft Volume Shadow Services (VSS)

File System Backups

File system backups are based on features available in storage arrays and specialized software products. While they’re not virtualization-specific, they can help simplify the process of creating and maintaining VM backups. Snapshot features can allow you make a duplicate of a running VM, but you should make sure that your virtualization platform is specifically supported. File system replication features can use block- or bit-level features to keep a primary and backup copy of virtual hard disk files in-sync.

Since changes are transferred efficiently, less bandwidth is required. And, the latency between when modifications are committed on the primary VM and the backup VM can be minimized (or even eliminated). That makes the storage-based approach useful for maintaining disaster recovery sites. While third-party products are required, file system backups can be easy to setup and maintain. But, they’re not always ideal for write-intensive applications and workloads.

Potential solutions include products from Double-Take Software and from Neverfail. Also, if you’re considering the purchase of a storage solution, ask your vendor about replication and snapshot capabilities, and their compatibility with virtualization.

Back[up] to the Future

Most organizations will likely choose different backup approaches for different applications. For example, application-level backups are appropriate for those systems that support them. File system replication is important for maintaining hot or warm standby sites and services. Guest- and host-level backups balance ease of backup/restore operations vs. the amount of usable disk space. Overall, you should compile the data loss, downtime and cost constraints, and then select the most appropriate method for each type of VM. While there’s usually no single answer that is likely to meet all of your needs, there are some pretty good options out there!

Evaluating Network-Based Storage Options

Sep 7

Posted by Anil Desai in Best Practices, Management | No Comments

This article was first published on SearchServerVirtualization.TechTarget.com.

Imagine living in a crowded apartment with a bunch of people that think they own the place. Operating systems and applications can be quite inconsiderate at times. For example, when they’re running on physical machines, these pieces of software are designed to monopolize hardware resources. Now, add virtualization to the picture, and you get a lot of selfish people competing for the same resources. In the middle is the virtualization layer – acting as a sort of landlord or superintendent – trying to keep everyone happy (while still generating a profit). Such is the case with disk I/O on virtualization host servers. In this Tip, I’ll discuss some options for addressing this common bottleneck.

Understanding Virtualization I/O Requirements

Perhaps the most important thing to keep in mind is that not all disk I/O is the same. When designing storage for virtualization host servers, you need to get an idea of the actual disk access characteristics you will need to support. Considerations include:

  • Ratio of read vs. write operations
  • Frequency of sequential vs. random reads and writes
  • Average I/O transaction size
  • Disk utilization over time
  • Latency constraints
  • Storage space requirements (including space for backups and maintenance operations)

Collecting this information on a physical server can be fairly simple. For example, on the Windows platform, you can collect data using Performance Monitor and store it to a binary file or database for later analysis. When working with VMs, you’ll need to measure and combine I/O requirements to define your disk performance goals. The focus of this tip is on choosing methods for storing virtual hard disk files, based on cost, administration and scalability requirements.

Local / Direct-Attached Storage

The standard default storage option in most situations is that of using local storage. The most common connection methods include PATA, SATA, SCSI, and SAS. Each type of connection comes with associated performance and cost considerations. RAID-based configurations can provide fault-tolerance and can be used to improve performance.

· Pros:

  • Generally cheaper than other storage options
  • Low latency, high bandwidth connections that are reserved for a single physical server

· Cons:

  • Potential waste of storage space (since disk space is not shared across computers)
  • Limited total storage space and scalability due to physical disk capacity constraints (especially when implementing RAID)
  • Difficult to manage, as storage is decentralized

Storage Area Networks (SANs) / Fibre Channel

SANs are based on Fibre Channel connections, rather than copper-based Ethernet. SAN-based protocols are design to provide high throughput and low latency, but require the implementation of an optical-based network infrastructure. Generally, storage arrays provide raw block-level connections to carved-out portions of disk space.

· Pros:

  • Can provide high performance connections
  • Improved compatibility – appears are local storage to the host server
  • Centralizes storage management

· Cons:

  • Expensive to implement – requires Fibre Channel-capable host bus adapters, switches, and cabling
  • Expensive to administer – requires expertise to manage a second “network” environment

Network-Based Storage

Network-based storage devices are designed to provide disk resources over a standard (Ethernet) network connection. They most often support protocols such as Server Message Block (SMB), and Network File System (NFS), both of which are designed for file-level disk access. The iSCSI protocol provides the ability to perform raw (block-level) disk access over a standard network. iSCSI-attached volumes appear to the host server as if they were local storage.

· Pros:

  • Lower implementation and management cost (vs. SANs) due to utilization of copper-based (Ethernet) connections
  • Storage can be accessed at the host- or guest-level, based on specific needs
  • Higher scalability (arrays can contain hundreds of disks) and throughput (dedicated, redundant I/O controllers)

· Cons:

  • Simplified administration (vs. direct-attached storage), since disks are centralized
  • Applications and virtualization platforms must support either file-based access or iSCSI

Storage Caveats: Compatibility vs. Capacity vs. Cost

In many real world implementations of virtualization, an important bottleneck is storage performance. Organizations can use well-defined methods of increasing CPU and memory performance, but what about the hard disks? Direct-attached, network-based, and SAN-based storage options can provide several viable options. Once you’ve outgrown local storage (from a capacity, performance, or administration standpoint), you should consider implementing iSCSI or file-based network-based storage servers. The primary requirement, of course, is that your virtualization layer must support the hardware and software you choose. SANs are a great option for organizations that have already made the investment, but some studies show that iSCSI devices can provide similar levels of performance at a fraction of the cost.

The most important thing to remember is to thoroughly test your solution before deploying it into production. Operating systems can be very sensitive to disk-related latency, and disk contention can cause unforeseen traffic patterns. And, once the systems are deployed, you should be able to monitor and manage throughput, latency, and other storage-related parameters.

Overall, providing storage for virtual environments can be a tricky technical task. The right solution, however, can result in happy landlords and tenants whereas the wrong solutions result in one seriously overcrowded apartment.