data protection for virtual server environments

8/9/2019 Data Protection for Virtual Server Environments

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Data Protection forVirtual Server Environments

Exploring Options and Technologies for Backup and

Recovery of Virtual Machines

White Paper

Kent Christensen, DatalinkAlan Howitson, Datalink

October 2008

Abstract:A dizzying range of technology choices awaits IT organizations trying to master the

art of data protection for virtual server environments. Those choices range from whether to use

familiar technologies, something new, or a combination thereof in order to effectively meet the

needs of the organization. Based on Datalinks insights gained from our experience protecting

enterprise data centers, this white paper provides practical advice and considerations surround-ing backup and recovery of virtual server infrastructures. We offer a glimpse at new data protec-

tion techniques and approaches that can help unlock the ultimate potential of an organizations

optimized virtual environment. We also provide details on how offloading much of the work

from the virtualized application infrastructure can help eliminate many virtual server backup

and recovery challenges. Given the current prevalence of VMware in many installations, this

paper focuses primarily on backup and recovery considerations in VMware environments.


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Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Early successes are not always easy to repeat . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Making good decisions for virtual server data protection . . . . . . . . . . . . . . . . . . . . .1

Common data protection challenges for virtual environments . . . . . . . . . . . . . . . . . . . . . . .2

Typical setting now includes hundreds of VMs . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Confusing options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Evaluating the options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Option 1: Backup agents and the use of third-party backup software . . . . . . . . . . . .4

Option 2: Server-based snapshots with VMware Consolidated Backup (VCB) . . . .5

High-level guidance on VCB operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Option 3: Storage array-based snapshots with array-based remote replication . . . .7

Other data protection considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

VMwares Site Recovery Manager (SRM) for remote replication . . . . . . . . . . . . . . .8

NAS (NFS) or SAN (Fibre Channel) for VMware backup/performance . . . . . . . . . . .9

Use of deduplication to reduce backup data footprints . . . . . . . . . . . . . . . . . . . . . . .9

Datalinks Enhanced Data Recovery (EDR) framework . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Applicable in a VM setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Datalink can help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Table of Contents


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Introduction

Early successes are not always easy to repeat

Todays data centers are in the midst of a massive revolution originating from

the move to virtual server architectures powered by solutions such as

VMware. Such growth is easy to understand. The benefits of server consoli-

dation via virtualization can be significant:

Dramatic savings in power/cooling costs and data center floor space

Cost savings from reuse and extension of existing assets

Simplified application management, rapid resource provisioning and the

ability to achieve new levels of application availability and portability

Given the widespread early success of virtual servers in organizations, many

have since chosen to enter the next wave of virtualization: Scaling the solu-

tion end-to-end througout the IT infrastructure and including enterprise appli-cations. However, as virtual server environments grow in size, the design and

day-to-day operation of such environments can become more complex.

Repeating success during the next phase of accelerated virtual server adop-

tion and growth can prove somewhat elusive.

To ensure the return on investment from virtualization is retained across the

data center, its important to look at the underlying network and shared stor-

age infrastructure supporting the move to virtual servers. The way IT organi-

zations choose to use other parts of their virtual server ecosystem for produc-

tion-level storage, archival, data protection and replication can significantly

impact overall savings. Such decisions can also impact how easy or hard it is

to manage and protect the virtual infrastructure.

The area of data protection offers a prime example of some of the complexi-

ties that can arise as a result of trying to scale out the virtual infrastructure.

Applying what have long been considered accepted data protection practices

during this accelerated growth phase can present significant challenges for

growing virtual server environments. Such challenges include concentrated

bottlenecks, performance slowdowns, and excessive data protection overhead.

Making good decisions for virtual server data protection

A dizzying range of technology choices awaits IT organizations trying to

master the art of data protection for virtual server environments:

Should you use whats familiar or adopt something different?

When does it make sense to combine multiple technologies?

What are some of the pros and cons of each approach?

Datalinks depth of experience protecting enterprise data centers allows us to

offer real-world insights for these types of questions. Based on many such

insights, this white paper provides practical advice and considerations sur-

.

Data Protection for Virtual Server EnvironmentsExploring Options and Technologies for Backup and Recovery of Virtual Machines

2008 Datalink. All Rights Reserved. www.datalink.com 1

The area of data

protection offers

a prime example

of some of the

complexities tha

can arise as a

result of trying t

scale out the vir

tual infrastruc-

ture.


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rounding backup and recovery of virtual server infrastructures. We offer a

glimpse at new data protection techniques and approaches that can help

unlock the ultimate potential of your organizations optimized virtual envi-

ronment and ultimately enable you to scale to an end-to-end solution with

higher demand enterprise applications. We also provide details on how

offloading much of the work from the virtualized application infrastructure

can help you avoid many virtual server backup and recovery challenges.

Given the current prevalence of VMware in many installations, this paper

focuses primarily on backup and recovery considerations in VMware envi-

ronments.

Common data protection challenges for virtual environments

Typical setting now includes hundreds of VMs

At the start of many early VMware deployments and pilot projects, IT organ-

izations only needed to concern themselves with protecting a handful of vir-

tual machines (VMs) on one or two ESX Servers. This proved a fairly simple

task with test/development and lower impact applications often involving

the same software-based backup solutions used when the applications existed

on separate physical servers.

However, as the number of virtual machines in production has grown to sup-

port an ESX Server farm and up to several hundred virtual machines, data

protection challenges have emerged. These include:

Data I/O bottlenecks as multiple application backup jobs and processes

become consolidated onto fewer physical servers

Backups consuming too much of an ESX Servers resources (CPU and

memory)

Backups consuming too much network bandwidth

Potential data I/O bottlenecks on the network as backup data moves to

and from each VM Guest OS, each ESX Server, the VMware

Consolidated Backup (VCB) proxy server, a third-party backup server

and its underlying shared storage target

Backup management issues surrounding lengthy backup processes and

increasingly complex job scheduling

Storage bottlenecks when many guests access the same storage devices at

the same time

Lengthy restores now involving more layers of abstraction and complexi-

ty and the need to manage different technologies working together



As the number ovirtual machines

in production

increased to sup

port an ESX

Server farm and

up to several hu

dred virtual

machines, data

protection chal-

lenges emerged


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Avoiding such backup bottlenecks and overuse of ESX Server resources is

one key to efficient data protection. Just as essential to success is applying

the right skills and knowledge to develop a comprehensive approach to data

protection. Such an approach should successfully address the virtual environ-

ments many-layered recovery needs from logical and physical recovery to

local recovery and remote recovery. All of these data protection needs must

now be considered and incorporated in todays now-maturing virtual world.

Confusing options

As VMware popularity has grown, a number of data protection options have

become available. As a result, the varied technologies and objectives sur-

rounding virtual server data protection and remote replication can resemble a

confusing maze for those still getting comfortable with the day-to-day opera-

tion of virtual machines. Even once an organization decides on a specific

technology path, the various offerings available from one or more vendors

can be complicated. Figure 1 demonstrates some of this confusion.

Beyond this, just as there is a proliferation of technology choices for virtual

server protection and recovery, there also exist as many goals and objectives

trying to be achieved within each VMware-enabled data center or line of

business. Deciding which data protection objectives are most important, in

order of priority, is not always easy.

Organizations must first sift through multiple options like those identified in

Figure 2 on the following page.



VMware popular

ty has grown an

as a result, seve

al data protectio

options are now

available.

Backup Agent in Guest OS?

Backup Agent in VMware Service Console?

Site Recovery Manager?

Backup with Deduplication?

Server-based snapshots?via VMware Consolidated Backup (VCB)

Storage Array-Based Replication?

VCB Proxy + Backup Software?

Storage Array-Based Snapshots?

Other technology choices impacting backup/recovery effectiveness

Potential Backup Targets Network Storage Protocol

- Disk - SAN (iSCSI/FC)

- Virtual Tape Library (VTL) VMFS

- Tape RDM (Raw Disk Mapping)

- NAS (NFS)

NDMP

Virtual Server Toolbox Presents Multitude of Options

Figure 1: There are several data protection options from which to choose in a virtual-

ized environment


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Evaluating the options

A myriad of options exist for backing up and recovering data in a virtualized

environment, three of which are summarized below.

Option 1: Backup agents and the use of third-party backupsoftware

In many ways, traditional backup performed via backup software agents has

been a popular choice in emerging virtual server environments. VMware

environments opting for this approach to data protection have tended to

deploy this option in one of three different ways:

1. Backup agent installed individually in each VMs Guest OS

2. Backup agent installed in the ESX Servers Service Console

3. Backup software integrated with VCB

Table 1 on the following page discusses the pros and cons of the first two of

these options. The third option is discussed in the next section describing use

of VCB.

In many ways, trditional backup

performed via

backup software

agents has been

popular choice i

emerging virtual

server environ-

ments.



What Are Your Goals?

Other Considerations

How often?- Frequency of backup/RPO, expected frequency of restores

How fast?

- Backup window, RTO

How easy?

- Management oversight, time needed for backup/restore

Remote Restore?Bare Metal Restore?

Crash-Consistent?

Granular File Restore?Full Image-Level Backups

(VMDK)?

Local Restore?

Application Aware?

Figure 2: A first step in developing a data protection strategy is to clearly define

your goals


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Option 2: Server-based snapshots with VMware Consolidated

Backup (VCB)

Recognizing some of the ESX Server resource contention issues that began

to appear with backup agents used inside each Guest OS, VMware released

VCB as an off-host backup alternative. Installed on a Microsoft Windows-based physical or virtual machine, VCB is responsible for properly quiescing

and restarting VM operations and the applications in the guest OS using

VMware Tools in order to take server-based, crash-consistent snapshots of

each VMs contents. VCB provides the following methods of accessing virtu-

al machine disk data:

SAN Mode Used with Fibre Channel and iSCSI storage to completely

off-load backups to a physical VCB proxy.



Approach: Backup Agent in the Guest OS (best used for file-level restores)

Pros Cons

One of the most popular methods

Often perceived as an easier data protection solu-

tion for smaller VMware installations as it requires

little change to pre-VMware backup processes

Can result in more targeted, application-specific

backups and restores

Can be implemented with some form of deduplica-

tion in the guest OS to minimize strain on band-

width and server CPU

(Potential caveats for deduplication: restore process

may be significantly more complex with client-side

deduplication. Other intermediate hardware may alsobe required.)

May unduly increase the backup window as the number of VMs

and backup agents proliferate

Added stress on physical server resourcesCPU cycles, memo-

ry, and bandwidthcan lead to potential performance and latencyissues as the number of backup agents and VMs grow per ESX

Server(ESX Servers tend to require more server resources to

support the added number of VMs and operating systems

installed)

Use of multiple backup agents and jobs can tax the IP network

used to transfer backup data

Can be costly to license multiple backup agents as VMs multiply

Backup scheduling issues and management complexity can grow

as administrators struggle to keep track of mounting backup jobs

that must share resources on the ESX Server and network

May not scale easily or support centralized, standard data protec-

tion processes to accommodate a wider range of applicationsespecially for applications that operate both inside and outside of

VMware

Approach: Backup Agent in the Service Console (VMDK-level restore only)

Pros Cons

Takes advantage of VM file encapsulation to backup VMDK files directly from the service console

Does not require installation of multiple backup

agents per each VM

Is not VM-aware or application-aware

Difficult to manage and only provides VMDK-level resources

While not as significant as each VM having a backup client, there

is still the added processing overhead on ESX Server resources

Table 1: The merits of using backup agents to protect virtual server data


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Hot-Add Mode Utilizes VM as a VCB proxy with any type of storage

visible to the ESX Server to perform backups that do not require exposing

SAN LUNS to the proxy server. The VCB proxy reads data through the

IO stack of the ESX host.

LAN Mode (NBD Mode) Best used when environment does not permitthe use of the SAN or hot-add modes. Leverages over-the-network proto-

col to access the virtual disk and send the data to the VCB proxy.

For best results with backup and restores of NFS, organizations should con-

sider using NDMP. Third party backup software integrated with VCB is

responsible for scheduling and initiating VCB snapshots. Once the snapshots

reside on the VCB proxy server, the backup software performs its routine

backup to disk, a virtual tape library or physical tape. Table 2 describes bene-

fits and disadvantages of this approach.



Approach: Using VCB

Pros Cons

Developed and supported by VMware with its

own built-in API

Supports both file-level backup/restore for

Windows VMs or full VM image backup

Offers an off-host backup method with direct

access to shared storage via the VMware file sys-

tem (VMFS) Can significantly reduce backup processing over-

head for ESX Server resources

Integrates with many popular third-party backup

applications

No need to mount volumes in order to perform

single file restores for Windows files

Uses VSS as part of VMware Tools for quiescing

on ESX Server 3.5 update 2 hosts, which allows

application-level quiescing on Windows Server

2003 and file system-level quiescing on Windows

Vista and Windows 2008 virtual machines

Backup software integration with VCB can vary greatly and may

require specific licensing structure, added scripting and extra

knowledge of the VCB command line interface

Single VCB proxy is limited in scalability by the host bus archi-

tecture and simultaneous backup sessions, so for environments

with hundreds of VMs, it is costly to scale across multiple physi-

cal VCB proxy servers

VCB proxy only runs on Windows, so file-level restores are only

supported on the Windows Guest OS and other VM environ-

ments (such as Linux and Solaris) only have the option to lever-

age full VM backups using VCB

Only supports RDMs in virtual compatibility mode, not physical

compatibility mode

Image-level backup is a two-step process (from VCB staging

area to backup destination), so full VM backup increases back-

up processing overhead and disk resources on the VCB proxy

and also complicates restores

Cannot scale to other data center environments (such as critical

Oracle implementations) that remain outside of VMware.

Does not integrate with VMware Site Recovery Manager (SRM)

for remote restores

Table 2: The merits of using VCB


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High-level guidance on VCB operations

For organizations that use VCB, Datalink recommends the following:

Determine backup levels and retention (SLAs, RTOs, RPOs)

Carefully consider the total amount of data to be backed up per backupwindows

Size the backup environment for peak workload

Determine whether or not you are performing VMDK-level or Guest OS

file-level restores

Plan extra space for the staging area needed for full VMDK backups

Minimize the number of simultaneous backup sessions to no more than

eight

Dedicate different HBAs for reading data (in VMFS), writing data (to the

holding area), and subsequent offload to tape or disk

Leverage third party backup integration modules to simplify backup man-

agement with VCB

Option 3: Storage array-based snapshots with array-based remote

replication

Just as with growing environments that operate outside of VMware, organi-

zations have begun to leverage the replication and snapshot capabilities avail-

able within their underlying intelligent shared storage systems for VMWare-

related backup, restore and remote replication.

The array-based snapshot option allows system administrators to perform

low latency block-level snapshots within the storage array, resulting in zero

impact on the ESX Server resources and production network. Because array-

based point-in-time (PIT) snapshots from some storage vendors provide near

instantaneous backup and restores, the freeze time for virtual disks until the

VMware snapshot can be deleted is greatly reduced compared to other back-

up approaches. A few different snapshot approaches are possible:

1. Snapshot copies with VMFS and RDM (FCP/iSCSI): Crash-consistent

VMDK datastore-level snapshots provide immediate PIT state. VMs are

grouped based on backup policy making recovery of the entire datastore

very easy. Since this is a LUN, individual VMDK file recovery requires

the LUN to be mounted.

2. Snapshot copies with VMDKs on NFS: Snapshot copies are still taken on

the entire volume, but because the virtual disks are not abstracted within a

LUN, individual files can be easily extracted.

3. Hot or warm application-aware snapshots: Snapshot process is inte-

grated with VMware for guest-to-VMDK consistency. When distilled

down to its simplest mechanism, this approach uses array-based integra-

Organizationshave begun to

leverage the rep

cation and snap

shot capabilities

available within

their underlying

intelligent share

storage systems

for VMware-relat

ed backup,

restore and

remote replicatio




10/13

tion modules or custom scripting to communicate with the VMware infra-

structure API to enumerate all VMs on a datastore and execute pre-freeze

and post-thaw operations to provide application-aware consistency. This

method requires more effort but poses less risk.

Table 3 describes pros and cons surrounding use of the methods above forstorage array-based snapshot and replication for VMware.

Other data protection considerations

Other technology decisions can also impact the effectiveness and efficiency

of data protection and recovery for VMware environments.

VMwares Site Recovery Manager (SRM) for remote replication

Site Recovery Manager (SRM) is meant to automate, ease and more effec-

tively monitor and test disaster recovery, with little-to-no impact on produc-

tion operations. SRM is designed to integrate storage-based replication func-

tionality with VMwares Virtual Center and a centralized management inter-

face and policy engine. It initiates functions like VM failover and rewriting

and restoring VMs remotely in the proper sequence and then coordinating

this with storage replication.



Approach: Using Storage Array-based Snapshots with Replication

Pros Cons

Depending on the storage system in use, can lever-

age resources from the physical storage array to

provide rapid, often highly efficient low-latency snap-shots, significantly minimizing the impact of the

backup process on growing VMware installations

Allows backups and restores to be applied data cen-

ter-wide, instead of only in the VMware environment

If performed with the NFS file system, file-level

restores are a faster, more straightforward process

for all OS environments (Microsoft Windows, Linux,

Unix, etc.), not just Windows environments

Backup proxy no longer needs to be a Windows

server, thus enabling a heterogeneous backup and

recovery environment

Can closely integrate snapshots and remote replica-

tion functionality (with some storage systems) to

offer efficient local and remote replication, often from

within a single toolset

More complexity may be introduced when working with VMFS and

Fibre Channel block storage layers

Application-level recovery may still require more than one

approach, depending on storage vendor features with regards to

virtual infrastructure-aware and application-aware integration mod-

ules

Levels of integration can vary by storage vendor and may still

require custom scripting and integration

Backup retention policy for VMs combined with datastore layout

needs to be carefully planned and considered before implementa-

tion

Table 3: The merits of using storage array-based snapshots with replication


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Note that SRM is currently only supported by use of the Fibre Channel SAN

and iSCSI protocols. It is also not integrated with VCB.

NAS (NFS) or SAN (Fibre Channel) for VMware back-

up/performance

Many VMware environments began their foray into shared storage using a

storage area network (SAN) based on Fibre Channel network connectivity.

This is understandable, given the wide support for Fibre Channel offered by

VMwares operating system (VMFS), and VMware features such as VCB

and SRM. As the VM footprint grew in size and complexity, organizations

began to revisit whether or not a network-attached storage (NAS) architec-

ture, based on NFS, might offer other benefits, such as:

More streamlined VM performance. NFS installations with VMware often

report the ability to support a greater number of VMs per ESX Server.

They also report the ability to avoid more common FC-based disk queu-

ing bottlenecks and SCSI reservation locks that would otherwise decrease

performance.

Greater simplicity and faster backup/restores when combined with snap-

shot functionality and the straightforward directory structure of NFS.

For a closer look at the merits and disadvantages of using FC, iSCSI or NFS

protocols with VMware, contact a Datalink representative.

Use of deduplication to reduce backup data footprints

Datalink has assisted VMware customers with deploying ancillary technolo-

gies such as data deduplication in their efforts to reduce the capacity of

VMware-related backup data transmitted and stored, both locally and remote-

ly.

There are a number of options for deduplication in the market. Some offer

client-side deduplication that is performed at the ESX Server (or within the

Guest OS) prior to backup data transmission. Others are appliances that oper-

ate in the network. Still others offer the ability to deduplicate primary

VMDK file data, while also being able to deduplicate secondary snapshot

backup sets and archives.

Datalinks Enhanced Data Recovery (EDR) framework

Applicable in a VM setting

Datalink has deployed its enhanced data recovery (EDR) model for years to

support the recovery and availability needs of mission critical applications in

several customer environments. This framework focuses on data center

growth, simplification of IT administration and the ability to successfully

blur the lines between data protection, disaster recovery and business conti-

nuity.

With the advent of VMware, the EDR model has also been refined for use in

virtual server environments. Still, its core tenets remain, including:

As the VM foot-print grew in siz

and complexity,

organizations

began to revisit

whether or not a

network-attached

storage (NAS)

architecture,

based on NFS,

might offer othe

benefits.




12/13

Reliance on disk-based backup and tape-based archiving, which has been

enabled by falling SATA-based disk prices and the use of mature,

advanced software functionality

Leveraging the performance, reliability and the random access nature of

RAID

Augmenting the abilities of tape

Data protection technologies and strategies underpinning the EDR frame-

work are shown in Figures 3 and 4.



ConventionalDisk

Virtual TapeLibrary

Point-in-TimeCopy

Continuous DataProtection

Data Deduplication

Replication

Cost of Protection

Cost of Lost Data

Cost of Recovery

Cost of Time

days hours seconds seconds hours days

$$$$$$ $$

$$$ $ $ $$$

Recovery Point Recovery Time

Enhanced Data Recovery Continuum

FailureOccurs

ESX Servers

SnapshotCopies

Replication

WAN

Storage Network

SRM

Storage Network

Figure 4: EDR with array-based snapshots and remote replication

Figure 3: EDR is a unique Datalink framework that incorporates disk-based technologies into data


13/13

Based on these tenets, Datalink has deployed a wide range of data protection

architectures for virtual server environments that incorporate various options

outlined in the previous sections of this paper.

Some of the most successful implementations, as shown in Figure 4, tend to

incorporate use of the following:

Array-based snapshots

Array-based remote replication

VMware SRM

Conclusion

Datalink can help

As a leading information storage architect, Datalink analyzes, designs, imple-

ments, and supports information storage infrastructures and solutions in a

variety of environments, including those heavily involved in server virtual-

ization. Not tied to one manufacturer or suite of products, we use technolo-

gies from multiple industry-leading and competing innovators and tailor

solutions to your needs.

With a strong base of technical resources, Datalink is known for unbiased

and balanced insights, field-tested best practices, and practical advice and

support that help todays data centers make the best use of technology to

meet business and IT needs.

VMware-based data centers are benefiting from Datalinks needs-driven data

protection practice and gaining ultimate reassurance of the merits of theirplanned solutions. Working with Datalink, organizations have access to cur-

rent proof points from Datalinks in-depth testing and interoperability lab,

where we incorporate VMware-based and backup software provider tech-

nologies as well as disk-based snapshot and replication technologies from

underlying storage solution vendors.

To learn more about how Datalink can help your organization sort through its

options for data protection with virtual servers, contact Datalink at (800)

448-6314 or visit www.datalink.com.

To learn moreabout how

Datalink can hel

your organizatio

sort through its

options for data

protection with

virtual servers,

contact Datalink

at (800) 448-6314

or visit

www.datalink.com


data protection for virtual server environments

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