The Economics of Tiers in Virtual Storage Pools

There are numerous companies that help cloud-enable apps, servers and networks. You’ve likely spent a fair amount of time strategizing with a few of them. Yet, it’s been our experience that storage considerations are often left for last; which inevitably leads to a mad scramble wrestling the many difficult, disk-related matters that no one had anticipated. We’d even go on to say that it is not at all uncommon for these seemingly peripheral issues to be overlooked altogether until they become a serious stumbling block in your rollout.

Fortunately, whether you’re in a panic, or early in your planning, you’ll find the guidance below timely and actionable. You see, DataCore, in partnership with our network of authorized solution advisors, offers consultation in the specialized domain of storage virtualization software – the state-of-the-art technology for tackling storage-related matters in IT organizations large or small.

We’ve accumulated strong credentials across 20,000+ installations spread across the globe. An increasing percentage of these aspire to host private clouds like you.

Cloud Reference Models

First, don’t be shocked at seeing the elaborate diagram (Figure 1) conceived by the National Institute of Standards and Technology (NIST). Think of it as the Reference Architecture for making a well-designed Cloud.

None of us pretend to be experts on these many service layers, but we do have a real good handle on the modules in the center of the diagram.

The Storage Side of Private CloudsKeeping it Light and Inexpensive

WHITE PAPER

AbstractIn the past 2 to 3 years, the storage side of private clouds has been weighed down by heavy iron, big spending and a lot of complexity. Throughout this white paper you’ll get acquainted with recent software developments and practices which reshape storage into a far more appealing and inexpensive component of your next generation IT environment.

Pressing Topics

• Contrast from typical data center

• Customer examples

• Where to get started

• Measuring success

• Transition Guidelines

• Resource Sharing & Provisioning

• Service Levels

• Automation

• Resiliency

• ChangeManagement

• Portability

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These incorporate those aspects of IaaS or Infrastructure as a Service, as well as the adjacent modules charged withabstractingandcontrollingthestorageresourcesunderneath.Morespecifically,theyhelpyouestablishhowsystemsshouldbeconfiguredandprovisioned;whatstepsyoucantaketoensureportabilityandinteroperability;doing so while shielding the surrounding layersfromtheinescapableproblemswhich hardware resources and the facilitieshousingthemcancauseyou.Theymayevenprepareyoutotakeonthosewildcurveballsthatthebusinessthrowsyourway. Let’s start slicing this downintomoredigestibleconcepts.

Not Your Typical Data Center

Analysts,suchasGartner,distinguishprivate Clouds from conventional IT practices using a few criteria:

Cloudsofferconsumersaself-serviceinterface using Internet technologies. Resourcesarenolongerpurchasedorassignedpermanentlytoaproject.Rather,theassetsarepooledandeachconsumer’s resource consumption

is metered in order to calculate costallocations.Bethatpurelyforinternalbudgetingpurposesoractualinternalbilling.Inthisregard,itisquitesimilartoapubliccloud.

Theprovider,namelyyou,isresponsibleforhostingascalable,sharedand,ideally,anautomatedinfrastructurethatcanstretchandshrinktofulfilluserdemands.We’llcoverhowsuchelasticityisachievedinasecond.Effectively,the consumer remains unaware of thecloud’sinternalworkings.Theysimplyinputprocessingrequirementsandgetbacktheirresultsfromthe

blackbox.Howquicklythoseresultscomebackdependsheavilyontheconduct of the storage infrastructure.

Drivers for Private Cloud

Understandthatbusinessagility,sometimesdefinedasthespeedwithwhichyoucanrespondtotheprocessingneedsofthecompany,isthenumberonereasondrivingmanyofyourcolleaguesto pursue a private cloud initiative (Figure3).Asmallerminorityisheadedtherebecausetheyhopetolowercostsover the long haul. Still others would prefertouseapubliccloudandunloadtheirITresponsibilitiesaltogether,buthavedeterminedthatthepublicroutedoesnotadequatelymeettheirservicelevel,regulatoryorlegalneeds.Therefore,theyhavetotakeownership.

Webringthisupbecauseithasmuchto do with setting expectations.

Theremaybeahandfulofyouthinkingthatthisprivatecloudstuffisbeyondyourreach.Buttheprinciplesdiscussedbelowstillapplytoyou.Infact,they’llhelpyouevaluateoutsourcingcandidates,shouldyouchoose to hire out the transition.

We’ve also run into smaller educational institutions and municipalities such as Saginaw Intermediate School Districtwho’vebandedtogethertoachieve critical mass where a collective privatecloudmakesperfectsense.

Fig.1-NISTCloudReferenceModelwithDataCore’srolehighlightedSource: National Institute of Standards and Technology

Source: GartnerFig.2-Privatecloudcharacteristics

Throughout the rest of this whitepaper wewillgetabitmoretechnicalwithhands-ontips,beginningwiththesubjectofResourceSharing.

Resource Sharing

In cloud lingo, sharing and pooling are nearlysynonymous.RatherthanisolateITassetslikedisksandSANsintospecificprogramsorprojects,ashasbeenthenorminyearspast,oneestablishesa shared resource pool from which differentconsumersdrawcapacity.

The pool consists of multiple storage tiers, each well suited to meetdifferentreliability,qualityofserviceorperformanceobjectives.The pool amortizes the cost of the underlyinginfrastructureacrossmanyconsumers.Italsoabsorbsthepeaksandvalleysgeneratedbyvariableuserworkloads.Sharingisagoodthing!

Recalltheabstractionlayerweintroducedacoupleofpagesback?Itplaysabigpartinhowspaceisshared,and is a central feature of virtualization.

Recognizethatwhatsubscribersaskforandwhattheyactuallyconsumecanvarygreatly.Mostappsoverestimatetheirfuturediskneeds.Theymakebloatedrequestsforverylargevolumesthatinpracticegoheavilyunderutilized.“Thin-provisioning”techniquesbuiltinto storage virtualization software dealwiththemismatchverywell.

Thin Provisioning

In essence, the software doles out small chunksofcapacityjust-in-timetotheconsumer,anddoessowithouttyingupallthespacetheyinitiallyrequested;Inotherwords,nohugepre-allocationofdisks.Still,theapp‘sneedsaresatisfiedwhiletheorganizationsaveslotsofmoney.Ofcourse,DataCore’sthinprovisioningsoftwaretakescaretonotifyyouwellbeforetheexistingdiskspacebecomesexhaustedtomakeabsolutelysurethatyouexpandcapacityaheadofdepletion.

No Downtime to Expand or Migrate

Ifyouthinkthat’scool,hereisanotherbeauty.Nodowntimeisnecessarytoaddnew drives into the virtual pool. The new diskscouldbefromdifferentsuppliers,ifyoucanmanageabetterbargain,sincenobackwardcompatibilityisrequired.

With resource sharing we mentioned tiers.Theseclassesofstorage,betheyhigh,medium,orlow,mapdirectlyintocloudservicelevelsandSLAs.However,thosetiersareappliedverydifferentlyin the cloud than the static assignments thatyoumaybeforcedintotoday.

Havealookatthegraphictotheleft. During the course of running an app, certain execution segments requiredifferenttypesofstorage.

Portionsoftheprogram,saySQLServerorOracle,mayrequirefast,top-of-the-line,FibreChanneldisksorpossiblysolidstatedrivesduringitsheavydata-inputcycle.Whereasthebulkofintermediatecalculationswilldofineusingbasic,reliablespaceonrealinexpensivediskdrives.

Source: GartnerFig.3-Driversforprivatecloud

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Fig.4-Variablestoragerequirementsfromwithinthesameapp

AllocatingSSDsexclusivelytothedatabasewouldbeacostlymistake.Anditwouldtieupthosevaluableresources,whilekeepingotherapplications from getting to them.

Whocouldpossiblyjuggleallthosedecisionsinrealtime?Clearlynotajobforeventhemostadroitcarbonrobots.No,themagicisinarecentdevelopmentknownasautomatedstoragetiering.

Thesystemadministratorneedonlysettheglobalpolicyforthecircumstancesthat merit premium vs. inexpensive storageoranythinginbetween,andthenhandsitofftothesoftwaretotakecareoftherest.Needlesstosay,youcanstilldefineextraordinaryworkloadsthatabsolutelymusthavethespeediest,mostbulletproofassets;particularlyforappslikegeneralledgerreconciliationrunduringspecificcrucialwindows.Butbyandlarge,themajorityofworkloadsaredealtwithautomatically.

Suchdynamicoptimizationofdiverseresources,especiallytogglingbetweenequipmentfromdifferentsuppliers, is on the leading edge of 21stcenturycloudtechnologies.

Whatseemslikeexceptionallywell-runningappstotheuseris

largelyaproductofawell-balancedarsenalofpurpose-builtdevicesorchestratedbyDataCore’sstoragehypervisor.Combinedwiththinprovisioning,theytranslateintomajorsavingsandbigtimeagility.

AsFigure5shows,distributionwise,we’ve found the median for fast SSD and Flash cards accounting for around 5%ofthepool’scapacity.Somewherein the 35 to 45% carved out from high-speedSASandFibreChanneldrives.Andthebalancemadeupofhigh-density,inexpensiveSATAdrives.

Hybrid Clouds

Interestingly,someofourcustomersoccasionallytapintopubliccloudstorage for short term extension to their privatecloudcapacity.Whichbringsustohybridclouds.That’swhereyouautotierbetweenyouron-premisesprivatelyownedassetsandoff-siterenteddisks,usuallyobtainedfromone of the commercial Cloud providers likeAmazon,AT&Tandseveralothers.Theextrabuffercomesinrealhandywhenyouneedalittlescratchspace,orwhenyouarchivedocumentsthatdon’twarrantthesamesecurityorregulatoryoversightasothervolumes.

It’s also a great option for storing contentsthatmayneedtoberecoveredafter a disaster; more on that in a minute.Butfirstweshouldaddressallthestandardizationtalkgoingaround.

Interchangeability

Youmayhavenoticedhowtightknitgroupsofvendorsareallyingtodictatebuildingblocksforprivateclouds,alwaysundertheguiseof“standardization.”Eachvendorclubhasadifferentrecipecalling out their hardware/software combination.Theirmessageimpliesthat choosing components outside the membercompaniescouldjeopardizeyourinstallationbecausethepieceshaven’tbeenpre-integrated.

Instarkcontrast,DataCore’sstanceonstandardizationenablescompleteinterchangeability;givingyouthefreedomtoharnessthebestpurpose-builtequipmentforeachtierinthecloud,regardlessofwhichfraternityis most popular at the time. We let youshopforthebestvalueamongcompeting hardware suppliers – all of whichhaveasuitablelineupofproducts.

It’smoreaquestionofwhomaybemorewillingtoearnyourbusinessnextgo-around.

Keytomakingthisworkisstickingtoestablisheddiskinterfaces,andtreatingstorageasnomorethanlargelyinterchangeablebucketsofdiskspace,tobereplacedwhentheirusefullifeexpiresandsomethingelsetakesitsplace.

Caching

Thereisanotherlessvisibletechnologyatplayherethatfiguresintothehigh-performanceresponsekeepinguserssmiling. We call it adaptive caching.

Ourcachingtechniqueshavebeenperfected over the past decade. Theyeffectivelymaintainfrequentlyaccesseddatainelectronicmemory

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Fig.5-TieredstorageacrossresourcesacrossHybridCloud

sotheycanbeaccessedmuchquickerthanwaitingonthemechanicaldisk.Similar methods are used in internet cachestoaccelerateyourwebbrowsingexperience.Adaptivecachingbooststheperformanceofdiskupdatesbeyondthe native speed of storage devices.

Besides the enhanced app response, thiscleverapproachtakescostoutoftheinfrastructure.Itallowsyoutoemploylessexpensivedisktechnologyin the pool and get faster results from equipmentalreadyonthefloor.Youknow-morebangforthebuck.

APIs

WhataboutthoseCloudAPIsyou’vereadabout?Itturnsoutthatmanyofthoseapplication programming interfaces are not so relevant when automation ismakingdecisionsonyourbehalf.

Havingsaidthat,upperlevellayersmust expose service catalogs to advertise what consumers can and can’t do.ButthoseactionstypicallyoccurabovetheIaaSstratumintheformofauser-friendlymenuselection.

Circumventing Outages Beforegoinganyfurther,whatdoyousaywespendafewminutesdealingwithmayhem?Yes,allthecrazyupheavalthatfollowsdisksaroundlikeaplague.Onthepositiveside,storagemanufacturersdoafantasticjobofimprovinghardwarereliabilityeveryyear.Buttheconstructioncrewsoutsideyourdatacentersseemlessconcerned.

Muchoftheunplanneddowntimethesedayshastodowithfacilityproblems;electrical,airconditioning,technicianerrors,leakyfaucets,toname a few. Emulate what professional hostersdoandyou’llbejustfine.It’sallaboutbuildingredundancyandcreatingalittledistancebetweenyourdataandharm’sway.

Ifyouaskus,keeptwocopiesofcriticaldata updated in separate rooms. Neversharethesamepower,HVACorplumbing.OK,sosharingisnotalwaysgood.Theroomscanbeafewfeetapartorupto100kilometersaway.Beyondthat,distance-relateddelaysstarttoappreciablyslowdownresponsetothe point where users complain.

Partofwhat’sneatabouttheDataCoresoftware is how it presents these two copies to the apps as a single coherent virtualdisksotheydon’thavetodoanythingspecial.InthebackgroundtheSANsymphony™-Vstoragehypervisorautomaticallykeepsthetwocopiessynchedup,transparentlyswitchingbetweenthemifonesideistakenout-of-service.Weusedevice-independentsynchronousmirroringoveracampusSANorlow-latencymetropolitanareanetworktokeeptheredundantimagesinlockstep.

Thisway,whentheA/Cunitkeelsoverinbuilding1andtheroomstartstoheatupanddrivesbegintoshutdown,theappisquicklyre-directedtothecopyinBuilding2withoutaglitch.Meanwhile,thesiteproblemscanbeaddressedunbeknownsttothesubscribers,andtheentireenvironmentcanberestoredandresynchronizedinthebackgroundoncethetemperatureisbacktonormal.

Worry-free Change Management

Inadditiontoshieldingyoursubscribersfrom unexpected environmental and facilityissues,redundancyplaysabigrole in eliminating planned downtime. Thesescheduledeventsdon’tusuallygetincludedinthewayITcountsoutages,buttheprivatecloudconsumerssuredo.

ThesecondarybenefitsofarchitectingforresiliencywithDataCoreisthatyoualsoachieveworry-free,non-disruptive, change management. Your team can repair, replace, upgrade and decommission storage and storage networkswithouthavingtoscheduledowntime.Anditcantakeplacewheneveryoudeemconvenient-preferablyduringnormalworkinghours.Soyourstaff,andyou,canspendholidayssomewhereotherthanthecomputerroomtryingtocompleteafranticdiskmigration.Fromtheconsumers’standpoint,everythingisworkingwellintheirCloud.

To put it in perspective, the prestigious NYPresbyterianHospitalrelocatedhalftheirdatacenterfromNewYorktoNewJerseywithouttakingdownusers.ThanksinlargeparttoDataCore.Theirhot-hotsitesarenowsplitacrossthe river separating the two states.

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RegionalDataCentersDisasterRecoverySite

Fig.6-Replicationtoensureresiliency

Mitigating Disasters

Thesecondphaseofyourbusinesscontinuityplanmustincorporatemorerobustdisasteravoidanceusingafarawaylocation.Theobjectiveis to safeguard the consumer’s information from regional threats or catastrophesthatcanaffectentiremetropolitanareas.I’mtalkingfloods,powergridfailures,earthquakes,hurricanes,andotheractsofGod.

Thetworeal-timecopieshousedwithin100kilometersfromeachothermaynotdoyoumuchgoodhere.A3rdremotecopyisrequired.

Inordertoimplementcost-effectivedisaster countermeasures, the DataCoresoftwarekeepsthedistantcopyreasonablyupdatedusingasynchronousreplication.Allyouneedisastandardlong-distanceIPWANconnectionbetweensites.

Ofcourse,thisextraprecautionimpliesadditionalinvestment.Consequently,itwouldbereservedforthemostcriticalinformationvolumes.Havingsaidthat,youmayuselowercosthardwareattheDRsitetocoverthesecontingencies. Some of our clients, for example,replicatetodistantbranchofficesequippedwithonlyrealbasicgear. The storage at opposing ends need notbethesame,becausethestoragehypervisorlayertakesresponsibilityforcopyingthedatabetweendissimilardevicesinahost-independentfashion.

Undoing Silly Mistakes

While we are on the topic of doom and gloom,yourprivatecloudstrategymustalsobecapableofreversingtheeffectsofvirusattacksandsillyusermistakes,regardlessofthediskdevicesusedtostorethedata.Frequentonlinediskbackupsmadepossiblebysnapshotsisone approach to restoration. But as fate wouldhaveit,theseuntimelyincidentsoftenoccurhoursafterbackups;which means that the consumer losesalotofvaluableworkiftheyrestorefromthepriorday’simage.

Morerecently,theinventionofcontinuous data protection (Figure 7) orCDP,allowsamoretimelyrollback,secondsbeforetheuserdeletedafile,orbeforethevirusinfectionarrived.CDPactslikeaDVR,soyoucanrollbackthevirtualdiskimageanywhereintimeupto48hours.Youthensurgicallyretrievethefileorwipecleantheviraleffects.Someliketocallitthe“Undobutton.”

CDPisusuallyreservedforselectdatavolumesbecauseittakesupmorediskspacetokeeparolling,time-stampedlogofthedata.Itsure is a powerful complement to online snapshots. Let’s go on now toahappiersubject–expansion.

Expansion

Healthyconsumptionofyourprivatecloud will cause it to grow.

Again,youarchitectforscalabilityupfront,layingoutthegroundworktoincreasenotonlydiskcapacity,butthroughput.Thisisaccomplishedbyscaling out the storage virtualization nodes commensurate with demand.

DataCoregivesyoutheuniquechanceto choose the most appropriate storagehardwareateveryexpansionor hardware refresh point. As well as selectthebestserverplatformonwhichthestoragehypervisorwillrun.Thesetoocanbeupgradedinplacetogetmore“oomph”fromyourITmuscles.

Comprehensive layer of device-independent services

Takealookatthiscollage(Figure8) framing the top level functions included in the DataCore software. The impressive capabilitiesoperateacrossallthepopularstorage devices, irrespective of the assortmentofgearthatyoumayhavechosen.Thefeatureshavebeeninternallydeveloped from the ground up and are managedcentrallyasanintegratedfunction set from a common console.

Uniform, central management in combinationwithautomationsimplifiesadministrationofyourprivatecloudandprovidestheportabilityandexpandabilitynecessarytotakeonthefuture.Recognizethatonemuststepoutsidetheembeddedcontrolsofindividualdevicestopulloffasuccessfulprivateclouddeployment.

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Continuous Data Protection (CDP)

Rewind to time before problem occurred

Fig.7-Reversingeffectsofusermistakesandmalware

Where to Begin

Butwhereshouldyoustart?Wewouldadviseyoutoconsideryourentrypointcarefully.Gartner,forexample,suggeststhatthemostsuitableworkloadstoinitiallytransitionintothecloudwillbethosewithshortlifespansandmore tolerant SLAs. These include development and test scenarios or sales demosandon-linetrainingcurriculaaswellaswebservers.Thesemakeexcellentcandidates,goodforfinetuningthenewself-servicemechanismsand usage metering utilities.

Measuring Success

Speakingofmeasurement,hereare some ideas for gauging success. It’s important to determine howyouwillassesssatisfactionwellbeforeyoulaunch.

• Areyoumoreagile?

> Expandtomeetspikes > Wind down when done

• Isyourenvironmentmoreflexible?

• Didyoulowercosts?

> Higherassetutilization > Fewer admins > Cheaper to expand

About DataCore SoftwareDataCoreSoftwaredevelopsthestoragevirtualizationsoftwareneededtogetthehighestavailability,fastestperformanceandmaximumutilizationfromstorageresourcesinphysicalandvirtualITenvironments.Itprovidesthecritical3rddimensiononwhichthesuccessofserveranddesktopvirtualizationprojectshinge,regardlessofthemodelsandbrandsofstoragedevicesused.

© 2012 DataCore Software Corporation. All Rights Reserved. DataCore, the DataCore logo and SANsymphony are trademarks or registered trademarks of DataCore Software Corporation. All other products, services and company names mentioned herein may be trademarks of their respective owners.

For additional information, please visit: www.datacore.com or e-mail: info@datacore.com

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Establishquantitativeandqualitativeyardsticks,operationalandfinancial.Anddothisfromboththeinternal IT end as well as from the consumer’svantagepoint.Theytendtobewaymoreobjective.

• Areyourusershappier?

o Responsiveapps

o Alwaysavailable

o Quickrecoveryfromusererrors

Inclosing,wewouldberemissnotto mention how important people, processes and policies determine how smoothlyyouwilltransitionintoaprivatecloud.DataCore’snetworkofconsultants and trusted advisors can helpyougetitrightfromtheoutset.

Fig.8-SANsymphony-Vfeaturessupportedacrossdiverseandmutuallyincompatiblestoragedevices

ANALYSIS & REPORTING

CENTRALIZEDMANAGEMENT

ASYNCREMOTE

REPLICATION

THINPROVISIONING

DISKPOOLING AUTO-TIERINGHIGH SPEED

CACHINGSYNC MIRRORING(HIGH-AVAILABILITY)

UNIFIED STORAGENAS/SAN

ONLINESNAPSHOT

CONTINUOUSDATA PROTECTION

& RECOVERY

DISKMIGRATION

LOAD BALANCING

RAIDSTRIPING

CLOUDGATEWAY