Virtualisation demands new provisioning plans
Wednesday, 13 May, 2009
How storage administrators provision data storage is changing in response to never-ending data growth and the popularity of money-saving technologies such as virtualisation and tiered storage.
The rise in popularity of virtual machines, and the speed at which they can multiply, means the storage team often has to figure out how to automate a provisioning process that in many shops is still a manual process.
At the same time, many organisations tier storage and have different types of drives, and that means storage administrators need to carefully plan and assess performance metrics and capacity when deciding which storage will work best with which applications.
SAN storage provisioning is more than simply formatting a drive, carving out a storage volume and assigning it an address, or logical unit numbers (LUNs). Other steps include mapping and masking the LUNs to enable the host to access them, zoning to specify which adapters can talk to which storage ports and configuring path management. Decisions points include the RAID level, the LUN size and an application's performance needs.
Brian Garrett, technical director of the Enterprise Strategy Group Lab, said that although fully automated end-to-end storage provisioning might sound great, getting there isn't so simple.
"First, it was a lot more complicated than we thought. There's a lot more heterogeneity that's needed," Garrett said. "But mostly, people didn't embrace it because there's workflow involved in large organizations. The DBAs, the server guys, the storage guys and the networking guys all have protocols and handoffs that they need to make along that process. They're not comfortable with a machine just automating and assigning these expensive resources and possibly introducing a risk of doing something wrong."
Table of contents
Virtualisation demands automation
Looking at block-based storage virtualisation
Vendors compete on automation, simplicity
Some users are choosing SRM software
Storage provisioning standards, scripting
VMware and secondary provisioning
Daniel Iacono, a SAN engineer at Philadelphia Insurance Companies (acquired last year by Tokio Marine Holdings), is looking to automate some aspects of the storage provisioning process through the scripting capabilities in his firm's Hewlett-Packard (HP) StorageWorks Enterprise Virtual Array (EVA) arrays. Even a simple script that would allow him to replace the host name and the LUNs, rather than going through the full rudimentary point-and-click process, could save some time when dealing with the company's growing virtual server environment.
The IT group's strategy is to virtualize wherever it makes sense. HP's Command View tool eases the provisioning process, and individual requests are generally handled in short order. But with the prospect of VMware ESX Server requests coming in bunches, automating steps of the provisioning process could help to minimise any wait time for the storage.
"That's why we're looking at automation," Iacono said. "Right now, it's a manual process. You physically have to have somebody carve off a LUN and present it to a server."
Another option under consideration is an NFS-based network-attached storage (NAS) device for the virtual environment. An administrator would simply need to take the file system on the NAS box and assign it to the ESX Servers. The servers would create Virtual Machine Disk Format (VMDK) files. And the storage administrator wouldn't need to do any major provisioning work, other than setting permissions for the NFS mount point, according to Iacono.
"There are tradeoffs," Iacono said. "If you provision using NFS, the performance is not as good as Fibre Channel. But the management tasks are easier."
The storage team may also scope out the prospects of internal cloud storage. The cloud would essentially operate as a single storage pool, eliminating the need for administrators to decide which arrays to use for different applications, Iacono said.
Block-based storage virtualisation is yet another option some storage shops consider to ease provisioning. organisations will find a wide range of products, from appliances to software-only options, operating at the array, the switch and the server. But no matter which they consider, the concept is the same: create an abstraction layer, or logical view, to enable the physical storage to appear as one large pool to an administrator.
Products include DataCore Software Corp.'s SANmelody and SANsymphony, EMC Corp.'s Invista, FalconStor Software Inc.'s Network Storage Server, Hitachi Data Systems' Universal Storage Platform V, IBM Corp.'s SAN Volume Controller, Incipient Inc.'s Network Storage Platform and NetApp Inc.'s V-Series. Storage virtualisation is also embedded into arrays from vendors such as 3PAR Inc., Compellent Technologies Inc., Dell Inc.'s EqualLogic and HP's LeftHand Networks Inc.
The technology, theoretically, can help storage administrators provision or manage across arrays from different vendors from one central place. But that's not what industry analysts typically see in practice. Instead, users tend to use storage virtualisation to help with provisioning, leveraging different storage tiers or migrating storage."Because of the continuing growth of storage and the continuing growth of server virtualisation, the only way you'll be able to effectively keep up with provisioning requests is through some sort of virtualized storage environment," said George Crump, founder of Storage Switzerland LLC, a Fort Worth, Texas-based consulting firm.
Most storage administrators often use the tools that are native to their arrays, although some still might prefer the command line interface (CLI). Element or device managers -- such as EMC's Symmetrix Management Console or Navisphere for its Clariion arrays, and HP's EVA Command View -- have matured and picked up features such as browser interfaces.
"They're all relatively easy to use compared to what you experienced five years ago, or even three or four years ago," said Barry Cohen, who both uses and tests products as chief technology officer at New York-based Edison Group Inc.
EMC's new Symmetrix V-Max system includes a feature called auto-provisioning groups. In the traditional provisioning process, administrators must individually mask each host port and map each volume to the storage port. Mapping and masking at the group level, using a wizard, can reduce the time to associate hosts to storage by 90% and cut down on errors, EMC claimed.
One prominent third-party tool that can assist with provisioning is Symantec's Storage Foundation, which consists of a volume manager, file system and dynamic multi-path components. The product has a central Web-based console to simplify administration. One function allows it to take volumes from any storage array that has been provisioned to a server and automate the steps to dynamically grow the volume without taking down the application, according to Sean Derrington, director of storage management and high availability at Symantec.
Some users turn to storage resource management (SRM) software to give them deeper insight into their infrastructures, from the storage devices to the network to the host bus adapters (HBAs) and, in some cases, even the applications. SRM tools include ControlCenter from EMC, Storage Essentials from HP, Tivoli Storage Productivity Center (formerly known as TotalStorage Productivity Center and still using the same acronym, TPC) from IBM, and Veritas CommandCentral Storage from Symantec.
Although the tools help with storage provisioning, they often facilitate, rather than complete, the provisioning. ControlCenter, for instance, makes calls to Navisphere or Symmetrix Management Console to do the actual provisioning work for EMC arrays, according to Scott Delandy, a senior product marketing manager at EMC.
EMC's SRM tool does not configure storage or do active device management of non-EMC arrays, although it is able to do discovery, reporting and auditing of the non-EMC environments, Delandy said. The discovery and reporting is achieved through support of the array profiles of the Storage Management Initiative Specification (SMI-S) put out by the Storage Networking Industry Association (SNIA), according to EMC.
Symantec's Veritas CommandCentral sends commands to the element/device managers to provision storage to several vendor's arrays, including those from EMC, and works with the vendor APIs to do the work that goes beyond the limits of SMI-S, according to Derrington.
HP's Storage Essentials is billed as supporting provisioning -- creating LUNs and masking them to a host -- in different vendors' arrays using SMI-S and/or the vendor-supplied APIs. The provisioning also extends to the zones in the fabric across the major switch vendors, according to Kalyan Ramanathan, director of marketing for Storage Essentials at HP.
IBM TPC's storage provisioning capabilities extend from the carving of the LUNs on the storage system to the mapping and masking of the LUNs, and also the ability to extend or grow a file system if the volume is running out of space, according to IBM. The product affords provisioning of both IBM and non-IBM arrays, as long as they support the appropriate SMI-S array profiles, said Jason Davison, a senior product manager with IBM's Tivoli storage.
"We're standards based. TPC uses SMI-S to do all of its storage provisioning. We don't talk to the APIs or the CLIs or anything like that," Davison said. "So, basically, every storage vendor that's SMI-S compliant and supports the specific profile to do provisioning, TPC can talk to and do provisioning for that storage system."
Greg Schulz, founder and analyst at The StorageIO Group, said that IBM's value proposition is its SMI-S standard support, but the approach comes at the expense of leveraging advanced vendor- or technology-specific features or functions that require the use of vendor-specific APIs or CLIs.
"It comes down to your preference of building around a standard, or standardizing your device element, provisioning and management toolsets," said Schulz, in an email. "Standards are great and should be an objective, however, not at the expense of adding complexity, or introducing extra management layers and cost, or inhibiting productivity."
In response, Davison wrote: "We strongly believe open standards driven by the SNIA organization provide customers with more flexibility in their management solutions, contrary to the closed, proprietary API approach that other vendors have instituted.
Davison said TPC's SAN planner functionality allows users to define criteria such as RAID levels and performance characteristics, and TPC will search the controllers and identify the target LUNs or storage pools that meet them. The tool provides recommendations and, if the administrator is satisfied, it can schedule or execute the commands to do the work.
HP stresses the need to take a holistic view of storage and its relationship to other pieces of the IT infrastructure. Its Storage Essentials tool provides a wizard that aims to ensure that customers provision in the right way, but provisioning is just one piece of the puzzle, said HP's Ramanathan. Storage Essentials is one piece of the company's Business Service Automation software suite, which also includes Operations Orchestration to help coordinate tasks, Server Automation and Network Automation.
VMware does allow administrators to provision storage and attach it directly to an individual virtual machine (VM). But it's far more common for the storage team to provision a large chunk of storage and let the virtualisation or server team carve it up as needed, according to Jon Bock, a group product marketing manager at VMware.
VMware doesn't provide the tools to provision the storage, but it does offer tools for the virtualisation team to do the secondary provisioning, allotting storage to the individual virtual machines, Bock noted.
"Typically, what we've seen with our customers is that the storage team doesn't want to get overburdened with all these requests for new storage," Bock said. "Given how easy it is to create a new VM, if they get a new request for storage on the SAN every single time that someone wants to create a new VM, they'll pretty quickly become the bottleneck."
Thin provisioning is a promising technology that could help to improve utilization rates for storage in a virtualized environment. Using it, administrators can present a large chunk of available storage to the server, but on the array, storage is allocated only as it is actually used.
Many of the array vendors offer support for thin provisioning, but now that VMware is also offering thin provisioning at the virtualisation layer, that may start to raise questions about who's in control of the storage.
"Is it the person who owns the VMs? Or is it the storage administrator?" said Bob Laliberte, an analyst at Enterprise Strategy Group, who noted that each could be doing thin provisioning independently of the other. "If your job's on the line to provide storage and you're doing thin provisioning, you really want to make sure that you know what the accurate picture is."
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