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Managing the information that drives the enterprise

STORAGEFOCUS ON

INSIDEVMware storage management evolves

vSphere 5 forges stronger storage bonds

SSD satiates vSphere memory appetite

While VMware server virtualization is prettymature, the way the platform interacts withstorage is not. But that’s changing. Find outhow your job to support storage for VMwareis getting easier.

Storage in aVMwareenvironment

Copyright 2011, TechTarget. No part of this publication may be transmitted or reproduced in any form, or by any means, without permission in writingfrom the publisher. For permissions or reprint information, please contact Mike Kelly, VP and Group Publisher (mkelly@storagemagazine.com).

Managingstorage

for virtualserver

environmentsVirtual servers and storage systems don’t have

to exist in separate worlds; new tools and plug-insprovide single-console management of both

virtual servers and storage. BY ERIC SIEBERT

vIRTUALIZED SERVERS HAVE created plenty of problems for datastorage managers, not the least of which is keeping track of therelationships between data storage assets and virtual servers.Some storage management products have adapted to this newenvironment, allowing users to keep track of virtual servers, theapps they host and the storage they’re using.

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FUNCTIONAL SILOSInside every data center there are typically silos related to specific functionalareas, each with a dedicated group responsible for management. There areteams responsible for managing specific data center resources, such as thenetwork, servers, storage systems and virtualization. Each group focuses onmanaging its own area and works with other groups when needed to handleintegration points between groups. If a new server requires shared storage,the server team works with the storage team to get storage provisioned andpresented to the server.In a traditional physical server environment, the storage group can easily

manage the relationships between storage and physical servers: a logical unitnumber (LUN) created on a storage area network (SAN) is assigned to a physicalserver and only that server uses the LUN. Server virtualization changes all that.But storage is perhaps the most critical component of a virtual infrastructure,so it must be implemented and managed properly for maximum performanceand reliability. The relationship between server virtualization and storage is atight one, so the management must be as well.

VMs CAN COMPLICATE STORAGEVirtualization is about the sharing ofa common set of physical resourcesamong many virtual machines (VMs).Virtualization file systems like VMwareInc.’s VMFS allow many physical serversto read and write concurrently to thesame LUNs. This is possible because of aspecial locking mechanism that ensuresmultiple hosts have exclusive access toeach of their VMs on a shared LUN.Among server virtualization’s strengthsare its features that provide high avail-ability and workload load balancingacross a virtualization cluster. Featuressuch as VMware’s vMotion and Storage vMotion can move VMs while they’rerunning from host to host as well as from one storage device to another.To further complicate things, the movement of virtual machines on storage

devices doesn’t just occur at the virtualization layer. Many storage arrays nowhave an automated storage tiering feature built around tiers of devices withdifferent performance characteristics, such as solid-state drives (SSDs) andSATA drives that are pooled and presented to a host. The array dynamically

Among servervirtualization’sstrengths are itsfeatures thatprovide highavailability andworkload loadbalancing acrossa virtualizationcluster.

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STORAGE Focus On: Storage in a VMware Environment

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moves data across tiers based on performance demands. All of that occurs atthe storage layer and the virtual host is unaware of the movement.While the features that move VMs around are beneficial, they can cause

headaches for storage and virtualization administrators as the relationshipsbetween virtual machines, the physical hosts they’re located on and thestorage device where their virtual disk resides is a dynamic one. That willhave the most impact when troubleshooting problems and monitoring per-formance. Because the virtualization admin is unaware of what’s occurringat the storage layer and the storage admin doesn’t know what’s happeningat the virtualization layer, neither gets to see the big picture.

PLUG-INS FILL THE MANAGEMENT GAPStorage vendors recognized the importance of tight integration between storageand server virtualization and have worked to develop software integrationwith existing virtualization management tools like VMware’s vCenter Server.VMware offers a solid set of vSphere APIs that allows third-party vendors tointegrate their products with vSphere.Also, vCenter Server has a plug-in archi-tecture that makes it easy for third-party plug-ins to seamlessly integratewith the vCenter Server admin interface.Plug-ins appear as a tab inside thevSphere Client, and their behavior andappearance can be customized. Thisallows options or information to bedisplayed that’s specific to a particularobject, such as a VM, host or cluster.Not all storage vendors were quick to develop vCenter Server plug-ins, but

most of the major storage vendors today offer plug-ins that allow their storagearrays to be monitored and managed from within vCenter Server. Each vendor’sstorage plug-in typically only supports specific storage array models andfamilies, and the plug-in’s functionality and features vary from vendor tovendor. Generally, storage plug-ins may offer these capabilities:

• Simplified expansion of virtual data stores. LUNs are created andpresented to hosts, which then create data stores such as VMFS volumesfrom them. To increase the size of a data store, the underlying LUN on thestorage array needs to be increased first. The plug-in allows both the LUNand VMFS volume to be increased from the same console.

• Storage provisioning. Storage admins can assign chunks of storage tovirtual environments; this allows virtualization administrators to create and

Plug-ins appearas a tab inside thevSphere Client, andtheir behavior andappearance canbe customized.

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size their own LUNs and manage the configuration of the storage.• Storage management. A plug-in can give virtualization administrators

the ability to manage storage array capabilities like LUN masking and thinprovisioning, and to set multi-pathing policies, set tiering policies, optimizeI/O settings and define access lists.

• Automated VM storage mapping. This type of plug-in lets you monitorand manage the physical/virtual relationships between the virtual machines,hosts and storage arrays. This can help the virtualization admin by mappingbetween the virtualization identifier and the storage array identifier for thesame disk.

• View detailed storage information. This brings information from thevirtualization layer and the storage layer into a unified view, and lets you seethe exact details of the physical storage layer from within the virtualizationconsole.

• Physical storage health monitoring. This capability provides informationon the physical health of storage arrays so virtualization admins will knowwhen physical hardware fails or becomes degraded.

• VM cloning. The cloning of VMs is basically just a data copy job that canbe offloaded to the array, which can do it more efficiently. This is especiallyuseful in virtual desktop environments that have larger VM density.

• Backup and recovery at the storage layer. This allows you to createpoint-in-time snapshots on the storage array of VM data stores. You can thenmount the snapshot and restore VMs from it as needed.

ANATOMY OF A PLUG-INThe joining of the storage and virtualization layers allows the virtualizationadmin to stay within the context of the virtual management user interface(UI) without having to grant access to a specialized storage management UI.Most of the storage plug-ins let you define credentials for the storage arraysthat will be managed inside the virtualization management console. This allowsseamless integration between the two consoles, and it’s also good from asecurity perspective as you don’t have to grant virtualization admins directaccess to the storage management console.Hewlett-Packard (HP) Co.’s approach to the integration of storage manage-

ment into vCenter Server was to leverage its Insight Control managementconsole and integrate portions of it within vCenter Server as a plug-in. Inaddition to a module to manage HP storage, the company included a moduleto manage HP server hardware. So both server and storage hardware can bemanaged from a single console. When the plug-in is installed, it creates aspecial HP storage privilege within vCenter Server that allows access to be

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granted to the HP storage plug-in. The plug-in brings storage managementinto virtualization but not vice versa. vCenter Server has very granular permis-sions and roles can be defined so access to storage-specific information canbe granted to storage admins. This allows storage admins to have a singleconsole to all the storage arrays integrated with vCenter Server.The HP Insight Control Storage Module for vCenter Server currently supports

the firm’s P4000, EVA, P9000/XP and P2000/MSA storage arrays. The plug-increates an HP Insight Software tab in vCenter Server that appears whenevera VM, host or cluster is selected; it also offers a menu option for actionssuch as cloning/creating virtual machines or creating data stores. The tabalso provides a storage overview of the object selected, such as storageprovisioned to a host, and storage provisioned by a host and the arrays it’sconnected to; it also provides links to directly launch the storage manage-ment console for an array. There are various views you can select to seedifferent information, such as Storage Disks and HBAs & Paths; you can alsocustomize the columns and choose from the many detailed storage fieldsthat are available. In addition, there are sections so you can see specificstorage objects related to the object you’ve selected, such as VMs, hostsand data stores.

Storage vendors’ vCenter Server

plug-insStorage vendor

Dell/Compellent

Dell/EqualLogic

EMC

Hewlett-Packard (HP)

HP/3PAR

IBM

NetApp

XIO

vCenter Server plug-in

vSphere Client Plug-in

EqualLogic Host Integration Tools for VMware(downloadable via Dell support site)

PDF describing multiple plug-ins(downloadable via PowerLink)

Insight Control Storage Module for vCenter

HP 3PAR Utility Storage and VMware vSphere

IBM XIV Management Console for VMwarevCenter

Virtual Storage Console

ISE Manager: vSphere Edition

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SINGLE-CONSOLE CONTROLIn addition to information about storage arrays, there are storage tools thatcan perform actions such as cloning a virtual machine by utilizing array-based replication, creating batches of new virtual machines, or provisioningstorage and creating VMFS volumes. While these tasks can be accomplishedwithin vCenter Server, the HP plug-in provides automation and offloads thetasks to the storage array, which can handle it more efficiently.

The vStorage APIs forArray Integration (VAAI)

VMware Inc.’s vStorage APIs were introduced in vSphere to allowtighter integration of advanced storage capabilities betweenvSphere and third-party storage applications and devices. There aremultiple categories of vStorage APIs that deal with different aspectsof storage integration. The vStorage APIs for Array Integration (VAAI)were co-developed with specific storage vendors (e.g., Dell, EMC,NetApp) to enable storage array-based capabilities directly fromwithin vSphere. Here are three examples of current VAAI features:

• Copy Offload. Virtual machine (VM) cloning or template-baseddeployment can be hardware-accelerated by array offloads rather thanfile-level copy operations at the ESX/ESXi host. This can also be appliedto other copy operations that occur, such as a Storage vMotion.

• Write-Same Offload. When provisioning an eager-zeroed virtualdisk (VMDK), the formatting process sends gigabytes of zeros fromthe ESX/ESXi host to the array. With write-same offload, the arrayhandles formatting of the eager-zeroed thick VMDK.

• Hardware-Assisted Locking. The traditional file-locking mech-anism using SCSI reservations is replaced by a more efficient mech-anism that is atomic (handled in a single operation). This allows foran increase in the number of ESX/ESXI hosts deployed in a clusterwith VMFS data stores.

As the vStorage APIs mature, expect to see even more offloadingand features at the storage array level, such as UNMAP support(return zeroed VMFS blocks), thin provision stun (stuns I/O if a thinvolume runs out of space), NFS file-level copy (analogous to XCOPYon block) and NFS advanced file attributes (so vSphere can betterunderstand more about files on NFS storage).

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The marriage of storage and virtualization in a single console allows fortighter management integration, which benefits virtualization admins but isless beneficial to storage admins. Virtualization admins can get more involvedwith some of the storage-related functions, but those are traditionally handledby storage admins, who may be reluctant to give up their control of provisioningand managing storage resources. Demonstrating the integration and features,and granting storage admins accessto the virtualization console, may helpconvince them to empower the virtual-ization admin to perform some basicstorage management. Even if virtualiza-tion admins aren’t allowed to managestorage resources, being able to viewdetailed storage array information isadvantageous by itself.While there are plenty of manage-

ment apps that integrate with VMware,there are plug-ins available for otherhypervisors, like EMC Corp.’s VirtualStorage Integrator for Hyper-V, whichintegrates with Microsoft Corp.’sSystem Center Virtual Machine Manager(SCVMM). Vendors have focused onVMware because of its popularity and because VMware has a deeper andmore mature set of APIs and SDKs. The storage integration plug-ins thatare available for virtualization are relatively new, and vendor offerings arestill evolving with more features and better integration. No matter whathypervisor you have, storage plug-ins are a must-have for any virtualizationenvironment, as they provide better visibility and integration, and enhanceyour ability to monitor, manage and troubleshoot your critical storageresources. 2

Eric Siebert is a virtualization expert who has written many articles for TechTargetwebsites.

The marriage ofstorage and virtual-ization in a singleconsole allows fortighter managementintegration, whichbenefits virtualizationadmins but is lessbeneficial to storageadmins.

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ITH vSPHERE 4’S vSTORAGE APIS, released in 2009, VMware Inc. madestrides toward addressing the way its platform interacted withstorage resources. But the company for the most part paid scantattention to storage management from within vCenter Server.vSphere 5, which VMware plans to release in the third quarter,is set to change that scenario. The latest version contains manyimprovements—both big and small—that make it an exciting releasefor storage. In this article we will survey all the new vSphere storageenhancements.

STORAGE Focus On: Storage in a VMware Environment

vSphere5givesabigboost

tostoragevSphere 5 contains many storage enhancements,

including a storage-centric DRS tool, Storage Profiles,a new API for storage awareness and an improvement

to an existing API, an increase to the LUN size limit,and improvements to Storage vMotion. BY ERIC SIEBERT

STORAGE Focus On: Storage in a VMware Environment

One important note: Because some of these new vSphere storage featuresrely on specific functionality built into storage arrays, you will need to makesure that your storage array supports them before you can use them. Typically,most storage vendors do not provide immediate support for new vSpherefeatures and APIs across all their storage models, so be sure and check withyour vendor to find out when they will support it.

STORAGE DRSIn what is perhaps the most notablestorage improvement in vSphere 5,VMware has expanded its DistributedResource Scheduler (DRS) to includestorage. In vSphere 4, when DRS triesto balance VM workloads across hosts,it takes only CPU and memory usageinto account and ignores storageresource usage. Storage I/O Controlallows you to prioritize and limit I/Oon data stores, but it doesn’t allow youto redistribute it. Storage DRS in vSphere 5 fixes that limitation by selectingthe best placement for your VM based on available disk space and currentI/O load. Besides initial placement of VMs, it will also provide load balancingbetween data stores using Storage vMotion based on storage space utilization,I/O metrics and latency. Anti-affinity rules can also be created so certainvirtual disks do not share the same data stores and are separated from oneanother. Data store clusters (also known as storage pods) are used to aggre-gate multiple storage resources so Storage DRS can manage the storageresources at a cluster level comparable to how DRS manages policies aswell as compute resources in a cluster.

STORAGE PROFILESvSphere 5’s Storage Profiles enable virtual machine storage provisioning to beindependent of specific storage resources available in an environment. Youcan define virtual machine placement rules in terms of storage characteristicsand then monitor a VM’s storage placement based on these rules. The newvSphere Storage Profiles will ensure that a particular VM remains on a classof storage that meets its performance requirements. If a VM gets provisionedon a class of storage that doesn’t meet the requirements, it becomes non-compliant and its performance can suffer.

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STORAGE

In what is perhapsthe most notablestorage improvementin vSphere 5, VMwarehas expanded itsDistributed ResourceScheduler (DRS) toinclude storage.

STORAGE

STORAGE Focus On: Storage in a VMware Environment

vSTORAGE APIs FOR STORAGE AWARENESSThrough a new set of APIs, the vStorage APIs for Storage Awareness (VASA),vSphere 5 is aware of a data store’s class of storage. The APIs enable vSphereto read the performance characteristics of a storage device so it can deter-mine if a VM is compliant with a Storage Profile. The vStorage APIs for StorageAwareness also make it much easier to select the appropriate disk for virtualmachine placement. This is useful when certain storage array capabilities orcharacteristics would be beneficial for a certain VM. The vStorage APIs forStorage Awareness allow storage arrays to integrate with vCenter Server formanagement functionality via server-side plug-ins, and they give a vSphereadministrator more in-depth knowledge of the topology, capabilities andstate of the physical storage devices available to the cluster. And, in additionto the functionality it lends to Storage Profiles, these APIs are a key enablerfor vSphere Storage DRS, by providing array information that allows StorageDRS to work optimally with storage arrays.

VMFS5 SIZE LIMITSThe new version of VMware’s proprietary Virtual Machine File System, Version5 (in keeping with vSphere 5), includes performance improvements, but thebiggest change is in scalability: The 2 TB LUN limit in vSphere 4 has finallybeen increased, to 16 TB. In vSphere 4, there is an option to choose fromamong 1 MB, 2 MB, 4 MB and 8 MB block sizes when creating a VMFS datastore. Each block size dictates the size limit for a single virtual disk: 1 MBequals 256 GB, 2 MB equals 512 GB, 4 MB equals 1 TB, and 8 MB equals 2TB. The default block size in vSphere 4 is 1 MB, and once set it cannot bechanged without deleting a VMFS data store and re-creating it. This causedproblems as many people used the default block size and later learned thatthey couldn’t create virtual disks greater than 256 GB. In vSphere 5, the blocksize choice goes away. There is only a single block size (1 MB) that can beused on VMFS volumes, supporting virtual disks up to a limit of 2 TB. Whilethe 2 TB LUN size in vSphere 5 has been increased, the single virtual disksize limit of 2 TB has not increased.For those upgrading to vSphere 5, porting existing data stores from VMFS3

to VMFS5 is seamless and non-destructive. But when you upgrade the volumeto VMFS5, it preserves the existing block size. If you want to get it to 1 MB,you have to delete the volume and re-create it. If you’re already at 8 MB, thereprobably is not much advantage to doing this. When it comes to LUN size,however, you can grow your LUNs larger than 2 TB after upgrading to VMFS5without any problems.

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STORAGE

STORAGE Focus On: Storage in a VMware Environment

iSCSI UI SUPPORTIn vSphere 5, VMware improved the user interface that is used in the vSphereClient to configure both hardware and software iSCSI adapters. In previousversions, to completely configure iSCSI support you had to visit multipleareas in the client, which made for a complicated and confusing process.In vSphere 5 you can configure dependent hardware iSCSI and softwareiSCSI adapters along with the network configurations and port binding ina single dialog box. And vSphere 5 has full SDK access to allow iSCSIconfiguration via scripting.

STORAGE I/O CONTROL NFS SUPPORTMany new storage features, upon release in vSphere, initially support onlyblock-based storage devices. Storage I/O Control (SIOC) is an example of thisconvention. SIOC enables you to prioritize and limit I/O on data stores, butpre-Version 5, it did not support NFS data stores. In vSphere 5, SIOC has beenextended to provide cluster-wide I/O shares and limits for NFS data stores.

vSTORAGE APIS FOR ARRAY INTEGRATION: THIN PROVISIONINGThe vStorage APIs for Array Integration (VAAI), introduced in vSphere 4, includethe ability to offload several storage-intensive functions from vSphere to astorage array. In vSphere 5, VAAI has been enhanced to allow storage arraysthat use thin provisioning to reclaim blocks when a virtual disk is deleted.Normally, when a virtual disk is deleted, the blocks still contain data, and thestorage array is not aware that they are deleted blocks. This new capabilityallows vSphere to inform the storage array about the deleted blocks so it canreclaim the space and maximize space efficiency.

SWAP TO SSDUsing solid-state drives (SSDs) as a storage tier is increasing in popularity.vSphere 5 provides new forms of SSD handling and optimization. For instance,the VMkernel will automatically recognize and tag SSD devices that are localto VMware ESXi or are available on shared storage devices. In addition, theVMkernel scheduler has been modified to allow VM swap files to extend tolocal or network SSD devices, which minimizes the performance impact ofusing memory overcommitment. ESXi can auto-detect SSD drives on certainsupported storage arrays; you can use the Storage Array Type Plug-ins (SATP)rules, which are part of the Pluggable Storage Architecture (PSA) framework,to tag devices that cannot be auto-detected.

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STORAGE

STORAGE Focus On: Storage in a VMware Environment

STORAGE vMOTION ENHANCEMENTS: SNAPSHOTS AND MIRROR MODEIn vSphere 4, if a VM had active snapshots it could not be moved to anotherdata store using Storage vMotion. In vSphere 5, that limitation has been removed.This is important because while Storage vMotion operations were not commonin vSphere 4, they are in vSphere 5 since the new Storage DRS feature will bemoving VMs between data stores on a regular basis as storage I/O loads areredistributed.Another Storage vMotion improvement relates to how changes are tracked.

In vSphere 4, VMware enhanced Storage vMotion by employing the ChangedBlock Tracking (CBT) feature to track block changes while a Storage vMotionoccurs instead of relying on VM snapshots. Once the copy process completed,the changed blocks were then copied to the destination disk. In vSphere 5 thecompany improved Storage vMotion even further, by abandoning CBT in favorof a new mirror mode. Instead of keeping track of blocks that change whilea Storage vMotion is in process and then copying them once it completes,Storage vMotion now performs a mirrored write, so any writes that occur duringthe Storage vMotion process are written to both the source and destination atthe same time. To ensure that the source and destination disks stay in sync,they have to acknowledge each write that occurs. In vSphere 4, VMs with a lotof CBT-related storage I/O had the potential of not keeping pace, in which casethe Storage vMotion process would eventually fail. This new process is moreefficient, much faster and avoids the potential for failure. 2

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wSTORAGE Focus On: Storage in a VMware Environment

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ITH vSPHERE 4’S vSTORAGE APIS, released in 2009, VMware Inc. madestrides toward addressing the way its platform interacted with storageresources. But the company for the most part paid scant attention tostorage management from within vCenter Server. vSphere 5, whichVMware plans to release in the third quarter, is set to change thatscenario. The latest version contains many improvements—both bigand small—that make it an exciting release for storage. In this articlewe will survey all the new vSphere storage enhancements.

Using SSD technology in a vSphere environmenthelps with memory overcommitment. Find out whatthe limitations of server hardware are, how memory

overcommitment works and why SSD is better atsupporting it than mechanical disk. BY ERIC SIEBERT

SSDsatiatesvSpherememoryappetite

STORAGE

STORAGE Focus On: Storage in a VMware Environment

One important note: Because some of these new vSphere storage featuresrely on specific functionality built into storage arrays, you will need to makesure that your storage array supports them before you can use them. Typically,most storage vendors do not provide immediate support for new vSpherefeatures and APIs across all their storage models, so be sure and check withyour vendor to find out when they will support it.

STORAGE DRSIn what is perhaps the most notablestorage improvement in vSphere 5,VMware has expanded its DistributedResource Scheduler (DRS) to includestorage. In vSphere 4, when DRS triesto balance VM workloads acrosshosts, it takes only CPU and memoryusage into account and ignores stor-age resource usage. Storage I/O Con-trol allows you to prioritize and limitI/O on data stores, but it doesn’t allowyou to redistribute it. Storage DRS invSphere 5 fixes that limitation by selecting the best placement for your VMbased on available disk space and current I/O load. Besides initial placementof VMs, it will also provide load balancing between data stores using StoragevMotion based on storage space utilization, I/O metrics and latency. Anti-affinity rules can also be created so certain virtual disks do not share the samedata stores and are separated from one another. Data store clusters (alsoknown as storage pods) are used to aggregate multiple storage resources soStorage DRS can manage the storage resources at a cluster level comparableto how DRS manages policies as well as compute resources in a cluster.

STORAGE PROFILESvSphere 5’s Storage Profiles enable virtual machine storage provisioning to beindependent of specific storage resources available in an environment. You candefine virtual machine placement rules in terms of storage characteristics andthen monitor a VM’s storage placement based on these rules. The new vSphereStorage Profiles will ensure that a particular VM remains on a class of storagethat meets its performance requirements. If a VM gets provisioned on a classof storage that doesn’t meet the requirements, it becomes non-compliant andits performance can suffer.

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If a resource shortageoccurs in any onearea on a host—suchas RAM—the numberof VMs that the hostcan run will berestricted despiteplentiful resourcesin other areas.

STORAGE

STORAGE Focus On: Storage in a VMware Environment

vSTORAGE APIs FOR STORAGE AWARENESSThrough a new set of APIs, the vStorage APIs for Storage Awareness (VASA),vSphere 5 is aware of a data store’s class of storage. The APIs enable vSphereto read the performance characteristics of a storage device so it can deter-mine if a VM is compliant with a Storage Profile. The vStorage APIs for StorageAwareness also make it much easier to select the appropriate disk for virtualmachine placement. This is useful when certain storage array capabilities orcharacteristics would be beneficial for a certain VM. The vStorage APIs forStorage Awareness allow storage arrays to integrate with vCenter Server formanagement functionality via server-side plug-ins, and they give a vSphereadministrator more in-depth knowledge of the topology, capabilities and stateof the physical storage devices available to the cluster. And, in addition to thefunctionality it lends to Storage Profiles, these APIs are a key enabler forvSphere Storage DRS, by providing array information that allows StorageDRS to work optimally with storage arrays.

VMFS5 SIZE LIMITSThe new version of VMware’s propri-etary Virtual Machine File System,Version 5 (in keeping with vSphere 5),includes performance improvements,but the biggest change is in scalability:The 2 TB LUN limit in vSphere 4 hasfinally been increased, to 16 TB. InvSphere 4, there is an option tochoose from among 1 MB, 2 MB, 4MB and 8 MB block sizes when creat-ing a VMFS data store. Each block sizedictates the size limit for a single virtual disk: 1 MB equals 256 GB, 2 MBequals 512 GB, 4 MB equals 1 TB, and 8 MB equals 2 TB. The default block sizein vSphere 4 is 1 MB, and once set it cannot be changed without deleting aVMFS data store and re-creating it. This caused problems as many peopleused the default block size and later learned that they couldn’t create virtualdisks greater than 256 GB. In vSphere 5, the block size choice goes away.There is only a single block size (1 MB) that can be used on VMFS volumes,supporting virtual disks up to a limit of 2 TB. While the 2 TB LUN size invSphere 5 has been increased, the single virtual disk size limit of 2 TB hasnot increased.For those upgrading to vSphere 5, porting existing data stores from VMFS3

to VMFS5 is seamless and non-destructive. But when you upgrade the volume

VMware storagemanagement

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Using an SSD as thestorage device forvirtual machine swapfiles allows you tomake use of memoryovercommitmentwithout taking a bighit in performance.

STORAGE

STORAGE Focus On: Storage in a VMware Environment

to VMFS5, it preserves the existing block size. If you want to get it to 1 MB,you have to delete the volume and re-create it. If you’re already at 8 MB, thereprobably is not much advantage to doing this. When it comes to LUN size,however, you can grow your LUNs larger than 2 TB after upgrading to VMFS5without any problems.

iSCSI UI SUPPORTIn vSphere 5, VMware improved the user interface that is used in the vSphereClient to configure both hardware and software iSCSI adapters. In previousversions, to completely configure iSCSI support you had to visit multiple areasin the client, which made for a complicated and confusing process. In vSphere5 you can configure dependent hardware iSCSI and software iSCSI adaptersalong with the network configurations and port binding in a single dialog box.And vSphere 5 has full SDK access to allow iSCSI configuration via scripting.

STORAGE I/O CONTROL NFS SUPPORTMany new storage features, upon release in vSphere, initially support onlyblock-based storage devices. Storage I/O Control (SIOC) is an example of thisconvention. SIOC enables you to prioritize and limit I/O on data stores, butpre-Version 5, it did not support NFS data stores. In vSphere 5, SIOC has beenextended to provide cluster-wide I/O shares and limits for NFS data stores.

vSTORAGE APIS FOR ARRAY INTEGRATION: THIN PROVISIONINGThe vStorage APIs for Array Integration (VAAI), introduced in vSphere 4, includethe ability to offload several storage-intensive functions from vSphere to astorage array. In vSphere 5, VAAI has been enhanced to allow storage arraysthat use thin provisioning to reclaim blocks when a virtual disk is deleted.Normally, when a virtual disk is deleted, the blocks still contain data, and thestorage array is not aware that they are deleted blocks. This new capabilityallows vSphere to inform the storage array about the deleted blocks so it canreclaim the space and maximize space efficiency.

SWAP TO SSDUsing solid-state drives (SSDs) as a storage tier is increasing in popularity.vSphere 5 provides new forms of SSD handling and optimization. For instance,the VMkernel will automatically recognize and tag SSD devices that are localto VMware ESXi or are available on shared storage devices. In addition, the

VMware storagemanagement

vSphere 5storage boost

Memoryproblems fix

Sponsorresources

17

STORAGE

STORAGE Focus On: Storage in a VMware Environment

VMkernel scheduler has been modified to allow VM swap files to extendto local or network SSD devices, which minimizes the performance impactof using memory overcommitment. ESXi can auto-detect SSD drives oncertain supported storage arrays; you can use the Storage Array TypePlug-ins (SATP) rules, which are part of the Pluggable Storage Architecture(PSA) framework, to tag devices that cannot be auto-detected.

STORAGE vMOTION ENHANCEMENTS: SNAPSHOTS AND MIRROR MODEIn vSphere 4, if a VM had active snapshots it could not be moved to anotherdata store using Storage vMotion. In vSphere 5, that limitation has beenremoved. This is important because while Storage vMotion operations werenot common in vSphere 4, they are in vSphere 5 since the new StorageDRS feature will be moving VMs between data stores on a regular basisas storage I/O loads are redistributed.Another Storage vMotion improvement relates to how changes are

tracked. In vSphere 4, VMware enhanced Storage vMotion by employing theChanged Block Tracking (CBT) feature to track block changes while a StoragevMotion occurs instead of relying on VM snapshots. Once the copy processcompleted, the changed blocks were then copied to the destination disk.In vSphere 5 the company improved Storage vMotion even further, byabandoning CBT in favor of a new mirror mode. Instead of keeping trackof blocks that change while a Storage vMotion is in process and thencopying them once it completes, Storage vMotion now performs a mirroredwrite, so any writes that occur during the Storage vMotion process arewritten to both the source and destination at the same time. To ensurethat the source and destination disks stay in sync, they have to acknowl-edge each write that occurs. In vSphere 4, VMs with a lot of CBT-relatedstorage I/O had the potential of not keeping pace, in which case the Stor-age vMotion process would eventually fail. This new process is more effi-cient, much faster and avoids the potential for failure. 2

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About Dell and VMware:Dell and VMware deliver efficient cloud infrastructure solutions that are fast to deploy, and easyto manage. The Dell | VMware® alliance is built upon a strong history of working together totest, certify and improve solutions involving VMware® technology on Dell servers and storage.