Your SlideShare is downloading. ×
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
E-Book: Real Solutions for Virtual Backups
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

E-Book: Real Solutions for Virtual Backups

371

Published on

After years of trying to figure out the best way to back up virtual servers, it looks like virtualization and backup software vendors are finally on the right track

After years of trying to figure out the best way to back up virtual servers, it looks like virtualization and backup software vendors are finally on the right track

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
371
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
8
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. E-BookReal Solutions for Virtual Backups Sponsored By:
  • 2. SearchStorage.com E-Book Real Solutions for Virtual Backups E-Book Real Solutions for Virtual Backups Table of Contents VM Backup is Better than Ever VM backup strategies: Backing up virtual machines in VMware vSphere Implementing data deduplication technology in a virtualized environment Virtual servers put pressure on backupSponsored By: Page 2 of 18
  • 3. SearchStorage.com E-Book Real Solutions for Virtual BackupsVM Backup is Better than EverAfter years of trying to figure out the best way to back up virtual servers, it looks likevirtualization and backup software vendors are finally on the right track.By Rich CastagnaSometimes it seems like the whole virtual server backup scenario is playing out in slowmotion. But if you really consider where we were just a few years ago and where we aretoday, an awful lot has changed.Four or five years ago, with a few virtual machines (VMs) here and there, most storagemanagers were content to toss a few more backup licenses into the mix and give each VMits own backup agent. It was a solution that certainly worked, but also one that just couldn’tscale.The new virtual environment also turned out to be a fertile breeding ground for backup appsbuilt from the ground up to do VM backup. A handful of apps tightly focused on VMwareenvironments have flourished within this niche, but while these backup packages can handleVMs very effectively, they tend to lack some of the features that traditional backup appshave acquired over the years. So many adopters have found that they need to run their VMbackup apps in tandem with their general purpose backup applications.VMware tried to ease the backup pain with VMware Consolidate Backup (VCB) but it provedto be little more than a stop-gap measure that added steps and, while it might’ve fixed afew things, added steps to an already complex process. Few shops adopted VCB and thosethat did saw limited benefits.All of that now seems like the virtual server dark ages as over the past couple of years theoutlook has gotten considerably brighter. Backup software vendors realized the specializedneeds of virtual environments and have updated their apps to meet those needs. VMware,too, came to a realization that it’s better to leave backup in the hands of the backup expertsand changed course accordingly, choosing to provide easy hooks into its environment viaAPIs that both backup software vendors and storage hardware vendors could exploit.Sponsored By: Page 3 of 18
  • 4. SearchStorage.com E-Book Real Solutions for Virtual BackupsThose events have helped trigger what is perhaps the most fruitful period of backup productdevelopment we’ve seen since virtualization began its march through the data center. Itmight be a stretch to say that virtual server backup is a snap now, but with more—andbetter—alternatives today, VM backup is definitely a lot less difficult than before.Rich Castagna is the Editorial Director of TechTarget’s Storage Media Group.Sponsored By: Page 4 of 18
  • 5. SearchStorage.com E-Book Real Solutions for Virtual BackupsVM backup strategies: Backing up virtual machinesin VMware vSphereProblems backing up virtual machines? Learn about the latest VM backup strategies whenbacking up VMs in VMware vSphere with this strategy guide.By Mark StaimerVM backup in a VMware virtual infrastructure has never been straightforward. This isbecause most backup administrators dont see a need to change their backup strategy whenthey move from backing up physical to virtual servers. They implement agent or clientsoftware on each VM just as if it were a physical machine. It worked in the physical world,so why wouldnt it work in the virtual world? Well, it does work, but with some caveats.Because backup software is optimized to back up as many servers/devices as it can in ashort a period of time (which makes sense when attempting to optimize for windows oftime), it can overwhelm the I/O of a server with multiple VMs. Imagine 10 VMs attemptingto be backed up concurrently from the same physical server. Even the latest x86 multicoreprocessors from Intel and AMD will choke.Then theres the agent/client software running on each of the VMs. Backup software almostalways (with some notable exceptions) requires an agent or client piece of software runningon the server being protected. This software scans the server for new data at the block orfile level and backs it up at the next scheduled backup timeframe. That piece of software istypically touted as being "lite," meaning low resource utilization. The most commonresource utilization number thrown around in the industry is approximately 2%. How thatnumber is achieved varies; however, it does not reflect the resource utilization when theagent/client software is actually performing the backup. Then those resources are muchhigher. Multiply that by the number of VMs and suddenly you have a serious bottleneck inoversubscribed resources.VMware recognized these backup problems and implemented VMware snapshots that take apoint-in-time snapshot of each VM or virtual machine disk file (VMDK) image. Subsequently,VMware integrated Windows VSS with VMDK snapshots for Windows applications makingSponsored By: Page 5 of 18
  • 6. SearchStorage.com E-Book Real Solutions for Virtual Backupsstructured applications (SQL server, Exchange, Oracle, SharePoint, etc.), crash-consistent.Next, VMware implemented VMware Consolidated Backup (VCB) that allowed each VMDKsnapshot to be mounted on a proxy Windows server thats backed up separately from theVMs themselves (e.g., no agents on the VMs). Unfortunately, it required additional externalphysical Windows servers and its performance was slow. With the release of vSphere 4.1,VMware has taken a giant step forward in making VM backups easier and more effectivethan ever before.VMware vSphere vStorage APIs for Data Protection and Changed Block TrackingIn vSphere, VMware introduced its vStorage APIs for Data Protection (VADP). VADP allows aphysical or virtual backup server to tell vSphere to take a VMDK snapshot of a specific VMand back it up directly to the backup server. The backup software may require an agent orclient software to run on the vSphere hypervisor, although it doesnt have to do so. Noagents or client software is required on the individual VMs.VADP also goes one step further. In the past, every VMDK snapshot was a full snapshot ofthe entire VMDK. This made backing up each VMDK snapshot a lengthy process. It alsothreatened backup windows as VMDKs continuously grow. The VADP in vSphere 4.1 addedChanged Block Tracking (CBT). CBT means that each new backed up VMDK snapshotcontains only the changed blocks and not the entire VMDK image.The vStorage APIs for Data Protection and Changed Block Tracking allow VMs to be backedup simply and without disrupting applications; however, they are only one piece of thebackup puzzle. They require backup software that utilizes these pieces. VMware itself offersa low-end package called VMware Data Recovery (VDR). VDR is limited to a maximum of100 VMs and 1 TB datastores. Theres no global capability and it doesnt replicate.The good news is there are many backup vendor products that are considerably morescalable, feature-rich and take full advantage of VADP and CBT. Vendors such as AcronisInc., Asigra Inc., CommVault Inc., EMC Corp., Hewlett-Packard (HP) Co., IBM Corp., PhDTechnologies, Symantec Corp., Veeam Software, Vizioncore (now Quest Software) and ahost of others.Sponsored By: Page 6 of 18
  • 7. SearchStorage.com E-Book Real Solutions for Virtual BackupsBacking up VMs doesnt have to be the massive headache that it has been. VMware isproviding new tools and backup vendors are leveraging them. Take a look at your VMbackup strategy today and talk with your backup vendor about VADP and CBT if you are notalready taking advantage of this easier, faster paradigm.BIO: Marc Staimer is the founder, senior analyst, and CDS of Dragon Slayer Consulting inBeaverton, OR. The consulting practice of 11 years has focused in the areas of strategicplanning, product development, and market development.Sponsored By: Page 7 of 18
  • 8. SearchStorage.com E-Book Real Solutions for Virtual BackupsImplementing data deduplication technology in avirtualized environmentMore environments are showing an interest in implementing data deduplication technologyin their virtualized environments. Find out whats driving this interest and what to watch outfor when using dedupe in your virtual environment.By Jeff BolesMore and more businesses are showing an interest in implementing data deduplicationtechnology in their virtualized environments because of the amount of redundant data invirtual server environments.In this Q&A with Jeff Boles, senior analyst with the Taneja Group, learn about whyorganizations are more interested in data dedupe for server virtualization, whether target orsource deduplication is better for a virtualized environment, what to watch out for whenusing dedupe for virtual servers, and what VMwares vStorage APIs have brought to thescene. Read the Q&A below.Table of contents: Have you seen more interest in data deduplication technology among organizations with a virtualized environment? Is source or target deduplication being used more? Does one have benefits over the other? Does deduplication introduce any complications when you use it in a virtual server environment? Are vendors taking advantage of vStorage APIs for Data Protection?Have you seen more interest in data deduplication technology amongorganizations that have deployed server virtualization? And, if so, can you explainwhats driving that interest and the benefits people might see from using dedupewhen theyre backing up virtual servers?Sponsored By: Page 8 of 18
  • 9. SearchStorage.com E-Book Real Solutions for Virtual BackupsAbsolutely. Theres lots of interest in using deduplication for virtualized environmentsbecause theres so much redundant data in virtual server environments. Over time, wevebecome more disciplined as IT practitioners in how we deploy virtual servers.Weve done something we shouldve done a number of years ago with our generalinfrastructures, and thats creating a better separation of our core OS data from ourapplication data. And consequently, we see virtualized environments that are following bestpractices today with these core OS images that contain most operating system files andconfiguration stuff. They separate that data out from application and file data in their virtualenvironments, and there are so many virtual servers that use very similar golden imagefiles with similar core OS image files behind a virtual machine.So you end up with lots of redundant data across all those images. If you start deduplicatingacross that pool you get even better deduplication ratios even with simple algorithms thanyou do in a lot of non-virtualized production environments. There can be lots of benefitsfrom using deduplication in these virtual server environments just from a capacity-utilizationperspective.What kind of data deduplication is typically being used for this type of application?Do you see source dedupe or target, and does one have benefits over the other?There are some differences in data deduplication technologies today. You can choose toapply it in two places—either the backup target (generally the media server), or you canchoose to apply it at the source through the use of technologies like Symantecs PureDisk,EMC Avamar or some of the other virtualization-specialized vendors out there today.Source deduplication is being adopted more today than it ever has before and itsparticularly useful in a virtual environment. First you have a lot of contention for I/O in avirtualization environment, and what you see when you start doing backup jobs there.Generally, when folks start virtualizing, they try to stick with the same approach, and thatswith a backup agent thats backing up data to an external media server to a target,following the same old backup catalog jobs, and doing it the same way they were in physicalenvironments. But you end up packing all that stuff in one piece of hardware that has allthese virtual machines (VMs) on it, so youre writing a whole bunch of backup jobs acrossSponsored By: Page 9 of 18
  • 10. SearchStorage.com E-Book Real Solutions for Virtual Backupsone piece of hardware. You get a whole lot of I/O contention, especially across the WANs,and more so across LANs.But any time youre going out to the network youre getting quite a bit of I/O bottleneckingat that physical hardware layer. So the traditional backup approach ends up stretching outyour backup windows and messes with your recovery time objectives (RTOs) and recoverypoint objectives (RPOs) because everything is a little slower going through that piece ofhardware.So source deduplication has some interesting applications because it can chunk all that datadown to non-duplicate data before it comes off the VM. Almost all of these agentapproaches that are doing source-side deduplication push out a very continuous stream ofchanges. You can back it up more often because theres less stuff to be pushed out, andtheyre continually tracking changes in the background; they know what the deltas are, andso they can minimize the data theyre pushing out.Also, with source-side deduplication you get a highly optimized backup stream for thevirtual environment. Youre pushing very little data from your VMs, so much less data isgoing through your physical hardware layer, and you dont have to deal with those I/Ocontention points, and consequently you can get much finer grained RTOs and RPOs andmuch smaller backup windows in a virtual environment.Does data deduplication introduce any complications when you use it in avirtualized environment? What do people have to look out for?When youre going into any environment with a guest-level backup and pushing full stringsof data out, you can end up stretching out your backup windows. The other often-overlooked dimension of deduplicating behind the virtual server environment is that you aredealing with lots of primary I/O thats pushed into one piece of hardware now in a virtualenvironment. You may have many failures behind one server at any point in time.Consequently, you may be pulling a lot of backup streams off of the deduplicated target orout of the source-side system. And, you may be trying to push that back on the disk or intoa recovery environment very rapidly.Sponsored By: Page 10 of 18
  • 11. SearchStorage.com E-Book Real Solutions for Virtual BackupsDedupe can have lots of benefits in capacity but it may not be the single prong that youwant to attack your recovery with because youre doing lots of reads from this deduplicatedrepository. Also, youre pulling a batch of disks simultaneously in many different threads.There may be 20 or 40 VMs behind one piece of hardware, and youre likely not going to getthe recovery window that you want—or not the same recovery window you couldve gottenwhen pulling from multiple different targets into multiple pieces of hardware. So think aboutdiversifying your recovery approach for those "damn my virtual environment went away"incidents. And think about using more primary protection mechanisms. Dont rely just onbackup, but think about doing things like snapshots where you can fall back to the latestgood snapshot in a much narrower time window. You obviously dont want to try to keep 30days of snapshots around, but have something there you can fall back to if youve lost avirtual image, blown something up, had a bad update happen or something else. Dependingon the type of accident, you may not want to rely on pulling everything out of the deduperepository, even though it has massive benefits for optimizing the capacity youre using inthe backup layer.Last year VMware released the vStorage APIs for Data Protection and some otherAPIs as a part of vSphere. Are you seeing any developments in the deduplicationworld taking advantage of those APIs this year?The vStorage APIs are where it started getting interesting for backup technology in thevirtual environment. We were dealing with a lot of crutches before then, but the vStorageAPIs brought some interesting technology to the table. They have implications for all typesof deduplication technology, but I think they made particularly interesting implications forsource-side deduplication, as well as making source-side more relevant.One of the biggest things about vStorage APIs was the use of Changed Block Tracking(CBT); with that you could tell what changed between different snapshots of a VM image.Consequently, it made this idea of using a proxy very useful inside a virtual environment,and source-side has found some application there, too. You could use a proxy with somesource-side technology so you can get the benefits of deduplicating inside this virtualSponsored By: Page 11 of 18
  • 12. SearchStorage.com E-Book Real Solutions for Virtual Backupsenvironment after taking a snapshot, but it only deduplicates the changed blocks that havehappened since the last time you took a snapshot.Some of these vStorage API technologies have had massive implications in speeding up thetime data can be extracted from a virtual environment. Now you can recognize what datahas changed between a given point in time and you can blend your source-sidededuplication technologies with your primary virtual environment protection technologiesand get the best of both worlds. The problem with proxies before was that they were kind ofan all-or-nothing approach. You use the snapshot, and then you come out through a proxyin the virtual environment through this narrow bottleneck that will make you do a wholebunch of steps and cause compromises with the way you were getting data out of yourvirtual environment.You could choose to go with source-side, but you have lots of different operations going onin your virtual environment.Now you can blend technologies with the vStorage APIs. You can use a snapshot plussource-side against it and get rapid extraction inside your virtual environment, and a finerapplication of the deduplication technology thats still using source-side to this one proxypipe, which mounts up this snapshot image, deduplicates stuff and pushes it out of theenvironment. vStorage APIs have a lot of implications for deduping an environment andblending deduplication technologies with higher performing approaches inside the virtualenvironment. And you should check with your vendors about what potential solutions youmight acquire out there in the marketplace to see how they implemented vStorage APIs intheir products to speed the execution of backups and to speed the extraction of backupsfrom your virtual environment.BIO: Jeff Boles is a senior analyst with the Taneja Group.Sponsored By: Page 12 of 18
  • 13. SearchStorage.com E-Book Real Solutions for Virtual BackupsVirtual servers put pressure on backupVirtual servers solve many problems in the data center, but they also make backup harder.There are several ways to back up virtual servers, each with advantages and disadvantages.By W. Curtis PrestonVirtual servers have solved a lot of problems in the data center, but theyve also madebackup a lot harder. There are several ways to back up virtual servers, each with uniqueadvantages and disadvantages.Backup is the single biggest gotcha for VMware nirvana in large environments today.The usual backup methods cause many environments to limit the number of virtualmachines (VMs) they place on a single ESX server, decreasing the overall value propositionof virtualizing servers. To further compound matters, one possible solution to the problemrequires purchasing additional physical machines to back up the virtual machines (VMs).However, there are existing products that can solve the problem, if youre willing to moveyour VMware environment to different storage. If thats not possible, there are some "BandAid" remedies that can help until storage-independent products arrive. However youultimately address virtual machine backup, you can at least take some comfort in knowingthat youre not alone in your frustration.The problem is physicsWhenever I consider VMware, I find my mind turning to the movie The Matrix. The millionsof VMs running inside VMware are very similar to all of the virtual people living inside themovies matrix. As with the movie, when you plug into the "matrix" —VMware, in this case—you can do all sorts of neat things. In the matrix, you can fly through the air; with VMware,VMs can "fly" from one physical machine to another without so much as a hiccup. In thematrix, you can learn Kung Fu and fly a helicopter in seconds. In VMware, a virtual machinecan run on hardware it was never designed for thanks to the HyperVisor.But when you die in the matrix, you die in real life because your body cant tell thedifference between virtual pain and physical pain. Similarly, VMware cant break theSponsored By: Page 13 of 18
  • 14. SearchStorage.com E-Book Real Solutions for Virtual Backupsconnection between virtual worlds and physical worlds. Although those 20 VMs runningwithin a single ESX system may think theyre 20 physical servers, theres just one physicalserver with one I/O system and, typically, one storage system. So when your backupsystem treats them like 20 physical servers, you find out very quickly that theyre runningin one physical server.Usual solution: DenialMost VMware users simply pretend their virtual machines are physical machines. In variousseminar venues, Ive polled approximately 5,000 users to see how theyre handling VMwarebackups. Consistently, only a small fraction of those who have virtualized their servers withVMware are also using VMware Consolidated Backup (VCB). The majority simply use theirbackup software just as they would with physical servers.Theres nothing wrong with doing it that way. A lot of backup administrators suffer from a"VMware backup inferiority complex" because they think theyre the only ones doing VMbackups that way. Theyre actually part of a large majority.If youre doing VM backups that way and theyre working, dont worry. The good thing aboutdoing conventional backups is the simplicity of the process. Virtual machine backups workthe same as "real" backups; you have access to file-level recovery, database and appagents, and incremental backups.Backup from inside ESX serverAnother option is to run your backup software at the physical level inside the ESX server.But things get ugly quickly and youll find yourself doing full backups every day. Youre alsolikely to be doing this without any support from your backup software company, which haslittle incentive to make this method work. (Theyd much rather you use VCB or even thetypical agent approach as they get more revenue that way.) The reason you end up doingfull backups every day is because any change in the VM results in a modification of thetimestamp of its associated VMDK files. So even an "incremental" backup will be the sameas a full. This is rarely the best approach to virtual server backup.Sponsored By: Page 14 of 18
  • 15. SearchStorage.com E-Book Real Solutions for Virtual BackupsVMware Consolidated Backup: Hope or hype?VMwares answer to the backup dilemma is VMware Consolidated Backup. To use VCB, youmust install a physical Windows server next to your ESX server and give it access to thestorage that youre using for your VMFS file systems. It can access both block-based (FibreChannel and iSCSI) and NFS-based data stores. The server then acts as a proxy server toback up the data stores without the I/O having to go through the ESX server.There are two general ways a backup application interacts with VMware ConsolidatedBackup. The first method only works for Windows-based VMs. With this method, the backupapplication tells VMware via the VCB interface that it wants to do a backup. VMwareperforms a Virtual Shadow Copy Service (VSS) snapshot on Windows virtual machines andthen performs a VMware-level snapshot thats exported via VCB to the proxy server as avirtual drive letter. (The "C:" drive on the VM becomes the "H:" drive on the proxy server.)Your backup software can then perform standard full and incremental backups of that virtualdrive.The main advantage to this method is the ability to perform incremental backups. Thedisadvantages are that its Windows only, theres no official support for applications(including VSS-aware apps) and no ability to recover the VM itself, only the files within thevirtual machine.Alternatively, you can use the full-volume method. VMware performs VSS snapshots asbefore, but can also perform syncs for non-Windows VMs. However, with this method, theraw volumes the VMDKs represent are physically copied (i.e., staged) from the VMFSstorage to storage on the proxy server. Although theres no I/O load on the ESX serveritself, this approach places an I/O load on the VMFS storage thats the same as a fullbackup.With standard backup products, this staged copy of the raw volume is then "backed up" totape or disk before its considered an actual backup. This means that each full backupactually has the I/O load of two full backups. And unless the backup software does a lot ofextra work, there are no such things as incremental backups. That means VCB—with a fewexceptions—creates the I/O load equivalent of two full backups every day.Sponsored By: Page 15 of 18
  • 16. SearchStorage.com E-Book Real Solutions for Virtual BackupsSymantec Corp. and CommVault have figured out ways to do incremental backups.Symantec uses the full-volume method for the full backup and the file-level method for theincremental backup, and then uses the FlashBackup technology borrowed from VeritasNetBackup to associate the two. Symantecs method significantly reduces the I/O load onthe data store by doing the incremental backup this way; however, it requires a multi-steprestore of first laying down the full volume and then restoring each incremental backupagainst that volume. This restore method is cumbersome, to say the least. CommVaultsmethod is to perform a block-level incremental backup against the raw volume, which is a"truer" incremental backup that offers an easier (and possibly faster) restore thanSymantecs approach. However, it must be understood that CommVaults method stillrequires copying the entire volume from the data store to the proxy server. Therefore, theirincremental backup places the equivalent of the I/O load of a full backup on the data storeevery day.Restoring a VM also requires two steps. Your backup software restores the appropriate datato the proxy server and then uses VMware vCenter Converter to restore that to the ESXserver. If the backup software supports it, it can do individual file restores by putting anagent on the virtual machine and restoring directly to it; however, restoring the entire VMmust be done via the two-step method.All of these issues contribute to the relatively limited adoption of VCB as a backup solutionfor VMs. While VMware said VCB has been licensed fairly extensively, my experienceindicates that a good number of those license holders have yet to implement it. Theressome hope for a better backup process, however, with VMwares vSphere.Some help from point productsThere are a few "point products" designed specifically to address VM backup that can beincorporated into the backup process to address some of these issues. VizionCore Inc. wasearly to the market with its vRanger Pro product, and has been doing VMware backupslonger than anyone else. Another popular alternative is esXpress from PHD VirtualTechnologies. Both products are able to do VMDK-level full and incremental backups, andfile-level restores with or without VCB. The two products think and behave very differently,however, so make sure you find the best match for your environment. Note that volume-Sponsored By: Page 16 of 18
  • 17. SearchStorage.com E-Book Real Solutions for Virtual Backupslevel backups with both products still require reading the entire VMDK file, even if they onlywrite a portion of it in an incremental backup.Source deduplicationYou can also use source deduplication backup software, such as Asigra Inc.s Asigra, EMCCorp.s Avamar or Symantecs NetBackup PureDisk. The first way source deduplicationbackup software can be used is by installing it on the VM where it can perform regularbackups. However, source deduplication backup requires fewer CPU cycles and is less I/O-intensive than a regular backup (even an incremental one), so it significantly reduces theimpact on the ESX server. Doing backups this way also lets you use anydatabase/application agents that the products may offer. The downside is that youre notusually able to do a "bare metal" restore of a VM if this is the only backup you do.Some products take this approach a bit further by running a backup inside the ESX serveritself, capturing the extra blocks necessary to restore the virtual machine. But this methodrequires the backup app to read all the blocks in all of the VMDK files to figure out whichones have changed. That could significantly impact I/O on the CPU as it calculates and looksup all those hashes.CDP and near-CDP approachesContinuous data protection (CDP) and near-CDP backup products are used in much thesame way that deduplication software is used. Theyre installed on your VM and back upvirtual machines as they would any other physical server. The CPU and I/O impact of such abackup is very low. Most CDP software wont allow you to recover the entire machine, soyoull need to have an alternative if your VM is damaged or deleted.Near-CDP-capable storageSo far, all of the methods covered have as many disadvantages as advantages—if not more.But theres a completely different solution that merits serious consideration: Use a storagesystem that has VMware-aware near-CDP backup already built into it. (Keep in mind thatnear-CDP is just a fancy name for snapshots and replication.) Dell EqualLogic, FalconStorSoftware Inc. and NetApp all have this ability. Other storage vendors are developing similarcapabilities, so check with your storage vendor.Sponsored By: Page 17 of 18
  • 18. SearchStorage.com E-Book Real Solutions for Virtual BackupsThe concept is relatively simple. VMDKs are stored on their storage, and each has a tooldesigned for VMware that you can run to tell it to back up VMware. VMware then performs asnapshot similar to what it does for VCB, allowing your storage box to then perform its ownsnapshot of the VMware snapshot. Replicate that backup to another box and you haveyourself a backup.The CPU hit on the ESX server is minimal. And the I/O hit on the storage is also minimal, asall it has to do is take a snapshot and then perform a smart, block-level incremental oftodays new blocks by replicating them to another system. (Note that this block-levelincremental is being done by the storage that already knows which blocks need to becopied, so the I/O impact is as low as it can be.) Vendors that offer these capabilities havetheir own ways of providing file-level restores from these backups as well.Dell EqualLogic systems, because theyre iSCSI, can communicate directly with the virtualmachines via IP to coordinate the snapshots. FalconStor has agents that run in all your VMsto coordinate snapshots and do the "right thing" for a number of applications. NetApp usesVMware tools to do snapshots; however, NetApps truly unique trait is that it can dedupeVMware data—even live data. Think of all of the redundant blocks of data you can get rid ofby using the deduplication tool included with NetApps Data Ontap operating system.Bottom line for VM backupThere are a number of technologies you can deploy today to make VMware backups better.However, many of them are still saddled with disadvantages, especially when compared totraditional backup processes. Perhaps the best current alternative is to move your VMwareinstances to VMware-aware near-CDP-capable storage. Or maybe VMware will solve some ofthese backup problems with vSphere.BIO: W. Curtis Preston is an independent consultant, writer and speaker. He is thewebmaster at BackupCentral.com and the founder of Truth in IT Inc.Sponsored By: Page 18 of 18

×