Realizing the Promise of Storage Virtualization


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Realizing the Promise of Storage Virtualization

  1. 1. A FORSYTHE WHITEPAPER Realizing the Promise of Storage Virtualization Where Does Storage and Data Virtualization Live? By Tony Johnson, Forsythe S torage Virtualization holds great promise for many IT organizations. This technology provides an abstraction layer between traditional host and array connectivity, without which, connected hosts on the SAN are impacted by the storage environment. With virtualization at the block level, each host no longer has direct visibility to its back end storage array(s)—thereby allowing daily operations, such as migrations, to occur in a non-disruptive fashion. These types of activities are normally disruptive to the stability of the storage environment. Two primary areas drive storage virtualization: DData Mobility SSimplified Management Data Mobility allows for data stored on logical units Storage and Data (LUNs) within a storage array to be moved through a Virtualization Services migration process. This migration process can be Before embarking on a storage virtualization endeavor, movement within a storage array or to another location it is important to understand the purpose of the initiative. outside the array. Movement within the array is often It is imperative that each customer keep three (3) clear part of intra-array storage tiering that leverages a multi- goals in mind: drive technology in one frame or footprint. Data mobility 1. Determine the key drivers for the solution or interest is a large concern for a number of IT organizations: 2. Decide what is to be realized from virtualization storage virtualization is an alternative to address the 3. Establish supporting ROI metrics to fund the migration concerns by allowing the process to occur endeavor (if necessary) without host downtime, relieving bandwidth capability pressures on not just the storage team but also on all of IT. With storage virtualization, metadata is used to Projects such as storage virtualization need to be match virtual LUNs as seen by the host to physical planned and socialized to gain the appropriate budget LUNs inside an array. The translation of virtual to for supporting the solution or direction. Storage physical happens in the virtual layer thus allowing non- virtualization generally relies on hard and soft cost disruptive movement of LUNs. savings around full-time equivalents (FTEs) and application downtime. However, substantial cost The promise of simplified management comes in savings may be found in tiering exercises such as re- various forms. Virtualization allows a single raid, re-tier and the reclamation of storage made management point for provisioning storage no matter available by the movement of storage data on LUNs what back end arrays exist once the storage has been from more expensive storage tiers to lesser cost storage provisioned to the virtualization layer using array-based non-disruptively, delaying the need to purchase more tools. It also allows for more advanced functionality higher priced capacity. such as replication, snapshots, clones and thin provisioning, all managed from the same management In a recent industry study from the Gartner group, the point. In fact, virtualization allows these functions determination of incorporating a services first approach regardless of the capability of the back end prior to hardware procurement proved to be the most prudent and profitable. Forsythe agrees with this array(s). A case in point would be thin provisioning. An approach and affirmed that this strategy has helped existing array may not be capable of thin provisioning; many enterprises achieve success. however, with the addition of the virtualization layer, that same array's LUNs can now be thin provisioned with virtualization. Many professional services organizations support the approach of Assessment & Design with "Best Fit" vendor selection. Some of the mentioned organizations in the Gartner study have vendor specific relationships
  2. 2. and some do not. The best return on the study would be from an organization that has multi-vendor Furthermore, with server virtualization becoming partnership so the customer can leverage the mainstream technology, associated storage knowledge, familiarity and understanding in the areas virtualization becomes more compelling. The same where they may not have a specific comfort level. efficiency and cost optimization drivers for servers apply to storage. These drivers include: The service offering should contain the following Data mobility across multiple heterogeneous elements: platforms • Review and baseline current environment Automated and policy based management • Determine conceptual technology solutions with ensuring that data is highly available and financial impacts resides in the right place at the right time at the • Determine vendor selection criteria with supporting right cost consistent with service level scorecards agreements and objectives • Provide final recommendations with clear prioritized Just as virtualization is changing the economics of roadmap to success servers and applications, virtualization is also a logical next step in the evolution of storage. Concerns Tools to Support Storage Virtualization Why Virtualize Storage? There are many tools available to companies when When storage first evolved from direct attached to embarking on the storage virtualization endeavor. The networked, the original challenges of inefficient organization must first understand the viability within utilization were thought to be addressed. These areas their environment, the technical and economical include: justification as well as potential pitfalls during integration and operations. Enterprises have a choice to pursue Storage island concerns with both internal FTE resources and outsourcing Performance capabilities. Where there are clear upsides with an Scalability external professional services organization regarding time, tools and SME capability, the internal direction is Manageability not without merit. Availability However, over time, networked storage and its Many companies’ IT departments have the required associated scale has produced its own set of storage expertise and industry knowledge to support the challenges. Instead of individual, direct attached storage technical aspects. Many also have an internal project islands, we now have SAN islands. In effect, management organization (PMO) that keeps stated heterogeneity has caused utilization and management project initiatives on time and on task. challenges. Even within one manufacturer’s product line, different tiers of storage can have different components, operating environments, and array-based Features and Functions software and management tools. The key to storage virtualization is flexibility and different approaches to "best fit" the pre-existing environment. The endeavor must include FTE SME Consequently, provisioning, expansions and upgrades, resources that understand the nuances between the tuning and troubleshooting, recovery and lifecycle high-level direction as well as the technical depth and management become complex, inflexible and labor detail at the physical solution base level. intensive. This new set of pain points results in less predictable performance, higher risk and increased cost HP Solution LeftHand SVSP of ownership. Features Non-Disruptive Data Mobility Growth enablement Performance Cost Effective Popular belief seems to dictate that storage Scalability Disaster Recovery virtualization adds unnecessary complexity and Availability Increased Uptime and performance impact to a storage environment. Internal Simple Availability array virtualization has been available for many management Easier server upgrade generations of arrays, such as the HP LeftHand series, process and has reduced the complexities of storage HA for multiple VM management while increasing standard array image copies performance. External virtualization solutions such as Functions Storage Clustering Heterogeneous the HP SVSP may seem complex architecturally but Network RAID volume manager lead to an overall simplification of the storage iSCSI Networking Business Copy environment due to simplified management particularly Thin Provisioning Continuous Access in a heterogeneous environment. With proper planning, Local & Remote Thin Provisioning performance can be maintained and sometimes Copy Centralized, Role- improved so that storage virtualization is a welcome based management addition.
  3. 3. Best Practices Understanding the required features and functions, with a realization of business and economic focus to secure Storage Virtualization Industry Practices the decision, is a pertinent piece to the readiness and Determining the business requirements and technology procurement process. concern for a storage infrastructure is the initial step when defining a storage direction that might include The actual features and functions vary from solution to virtualization. Storage virtualization offerings have solution. The HP solutions of LeftHand and SVSP vary matured the second half of this decade and are as well. Here are a few key features and functions for continuing to capture interest. Storage administrators each: are attracted to virtualization because the solution unifies management, and managers like the technology that will simplify data migrations and improve overall operational efficiencies. Unification and simplification In/Out of Band Management have been recognized as key contributors for driving In-Band and Out-Of-Band management is in reference higher utilization rates. IT directors and CIOs are to how storage virtualization has an impact on the actual pleased with the fact that virtualization can help further input and output (I/O) traffic between a host server OS commoditize storage which provides additional leverage and a source storage array. during negotiations driving lower costs. An In-Band virtualization configuration is defined by Key Planning Questions having the virtualization engine in the data path, which receives the I/O requests from the host, and completes How are the business or application owners affected by those requests to the array on behalf of the host. In application outages and what service levels are in place? many cases, this could actually improve the response Is there a storage services catalog that defines service time from the host's perspective as the virtualization levels back to the application? engine will sometimes acknowledge I/O faster than some aging or heavily utilized arrays. Once the requirements are determined, what will the architecture and/or configuration look like? Out-Of-Band virtualization is defined by having the What array or features are required? virtualization layer not impact I/O traffic. The redirection of I/O from host file system to physical storage happens Is storage allocation vs. utilization understood and is at the hardware layer of the SAN switching architecture there an issue with over provisioning? at wire speed with I/O acknowledgement coming from What is the storage chargeback model? the array, not the virtualization layer. Control functions of the virtualization engine and SCSI commands other What benefits will be gained by implementing a new than reads and writes are carried out by an Out-Of-Band technology direction? appliance that is not in the data path. It is important to start educating internal customers on how new technologies will directly affect them and how Setting Polices processes could change. Storage centralization is a Prior to setting the policy attributes within the fundamental part of any virtualization strategy and it is virtualization solution, it is important to thoroughly important to start socializing this with the application understand the policy requirements of the environment, owners encouraging them to move to a shared storage applications, servers and lines of businesses the model if one is not already in place. Defining and solution will be the central point of contact. Since standardizing a storage service catalog goes along with storage virtualization allows a pass-through to storage centralization and moderation design compatible legacy arrays, it is important to catalog, methodologies. By offering application owners storage categorize and constantly inventory the support use of service levels, this provides a level of abstraction to the the element behind the virtualization solution for business and will simplify the storage request process appropriate alignment. thus adding flexibility to the way storage is managed and provisioned to the customer. This helps remove the speeds and feeds conversations that some application As for setting policies, the management utility has many administrators can get hung up on, moving that different configurations. It can be used out-of-the-box responsibility to the storage team. and is highly configurable. Obviously, the out-of-the-box policy definitions would be generic in nature and will require administrative supervision for appropriately At a high level, storage virtualization can be placed into assignments. It is highly recommended to complete the three categories or layers in the virtualization stack. areas of catalog, categorization and inventory of current 1. Application or server operating system virtualization usage and plot into a policy matrix for proper such as Symantec Foundation Suite is the first configuration upon solution integration and category and the highest layer in the stack. implementation.
  4. 4. a. Basic virtualization functions such as RAID storage and lowering potential risk to the environment. sets and volume mirroring The storage team will still require management tools 2. The second virtualization layer would be network or and optics that provide capacity reporting capabilities to SAN fabric based services that include products help proactively plan storage upgrades and provide like HP SVSP. sufficient lead times for the procurement cycle. It is important to consider that adding virtualization to an a. Advanced functionality like thin environment provides a new way of doing things and provisioning, replication, data mobility thus required proper planning, testing and education. across all virtualized storage 3. The lowest layer in the stack, and most widely used Automation and Operations today, is array based virtualization a. Advanced functionality like thin Automation provisioning, replication, data mobility inside the array Most storage virtualization products on the market today contain some level of automation. Most of this The higher up the stack storage is virtualized the more automation revolves around the ability to make PIT storage becomes commodity and the less dependence (point-in-time) copies of data residing on a virtualized there is on a particular array manufacturer and the array, or automated failover in the case of a disk array software features that are in the array which help reduce or disk group failure. cost. The automation of PIT copy creation usually takes two Three basic storage or data tiers would be part of a forms. First, the ability to schedule the creation of the storage-virtualized infrastructure. copy through the management GUI, and that PIT copy 1. The first data tier relies on the most expensive software's ability to interface with a server or Virtual fiber channel, feature rich high-end enterprise Machine and with a database on that machine to get a class array. consistent copy of the data at that point in time. Second, the ability 2. The second data tier is comprised of midrange to use CLI commands to create the PIT copy, for low-end fiber channel or iSCSI enterprise class incorporation into user scripts. If an application is tied to array. an array toolset (replication, cloning, etc.), it is important to consider the impact of adding virtualization to these 3. The third data tier is a low-end fiber channel, applications and the scripting changes that may be iSCSI, SAS (Serial Attached SCSI) array with required. minimal feature set and functionality. Both HP SVSP and HP LeftHand solutions offer There are gaps between each tier and data movement automated creation of PIT copies of LUNs, both through between tiers without virtualization is a labor intensive the management GUI and with CLI commands. Since process that can induce unnecessary risk into the the destination storage pool can be selected ahead of environment. Addressing the gaps between data tiers is time, the PIT copies could reside on lower tiers of where storage virtualization, particularly at the storage within the same disk array, or in a different disk application or SAN fabric services layers, can help close array. This allows the user the ability to enjoy the full gaps within a storage infrastructure by providing unified useful life of a wide array of storage platforms for their management, data mobility and higher storage storage tiers, and not be locked into each arrays utilization rates. replication and management software tools. When selecting a virtualization solution items to Both HP SVSP and HP LeftHand solutions offer consider are product maturity, simplification, automated failover in the case of a disk array or disk interoperability, and feature requirements. group failure, assuming the LUNs that are presented to Interoperability is a critical item that can be overlooked servers have been correctly configured behind those during the selection process. Checking qualification virtualization products to withstand a disk array or disk matrices for server operating systems, HBAs, SAN group failure. This means using more than one disk directors and switch, and array patch levels save array as a storage resource when creating LUNs for considerable time during implementation or can presentation to servers. potentially disqualify some solutions for an environment. Product maturity is another important aspect and customer references should be requested. Proper Operations education is another requirement that should not be One of the benefits of storage and data virtualization is overlooked as storage virtualization is a net new the ability to manage the day to day aspects of the technology to the environment and should not be storage environment such as provisioning through a trivialized. This will help ensure a smooth "single pane of glass". While being able to completely implementation and transition to the new infrastructure manage storage arrays from more than one vendor in and help drive administration efficiencies by enabling a one software tool is still some time away, for a variety of storage administrator the ability to manage more reasons, many of the common management tasks can
  5. 5. be performed with the incorporation of standards by storage arrays, or arrays from different vendors. The storage service tier. ability to add software features to arrays that do not have those features is a key benefit to SAN based virtualization. Once service level criteria are defined for each storage tier, and arrays are chosen to support each storage tier, those arrays can be completely configured in advance Both HP SVSP and HP LeftHand solutions offer a single to meet those criteria. Storage virtualization platforms tool to manage storage assets, as well as to manage can utilize LUNs once they are presented to it, so pre- replication for any storage that virtualized through them. configuring the underlying storage arrays is a critical step to enjoying management of the arrays from a single software tool. Preparation Checklist for Storage Virtualization Prior to deciding, procuring or sponsoring the installation Here are examples of Tier 1 and Tier 3 service level of a storage virtualization solution, the customer should criteria: have a keen understanding and awareness that any storage virtualization solution is a technology enabler Service Criteria / TIER 1 TIER 3 and is a part of the overall solution. Many customers Attributes have operated under the misconception that the solution is a utility that requires little pre-requisite planning or LUN Sizes 50GB, 200GB 250GB, management after implementation. Complicating this 500GB fact is the thought that the solution will cure all issues and concerns. Many items need to be evaluated both RAID Level RAID 1 RAID 5 internally as well as during the solution selection Drive Type Fibre Channel SATA, 7200 process. (FC), 15K RPM RPM Concerns Checklist of Preparation Questions *The table above provides definition and detail around Compatibility Are there challenges with the terms expensive tier disk and lesser cost disk. heterogeneous storage arrays? With the service level criteria above, the disk arrays that Utilization What are the current utilization rates have been selected to contribute to Tier 1 and Tier 3 within the storage environment? storage would be pre-configured to those specifications, Reporting tools? using the individual array's management software. All Protection Are there integrated software products other functions would be handled by the virtualization for snapshot and/or remote replication platform, such as LUN presentation and local/remote in use? replication. Solution What is the best course of action for the current environment? (In-band or Different standard LUN sizes were used above as a tool Out-of-band) to help system administrators differentiate between LUNs on separate tiers. Some virtualization solutions Performance What are the performance allow pools of back end devices that can be used to requirements? (SLA, OLA, Storage differentiate performance level LUNs from capacity level Catalog) LUNs. Since the back end array characteristics can be transparent, it is important to understand those back- end characteristics to ensure application performance Simply stated, storage virtualization is a vehicle for the and service levels with a virtualization solution. storage engineer, architect, manager and/or administrator to simplify the provisioning of the storage resources and reduce the heterogeneous complexity of When using LUN sizes to differentiate between storage storage infrastructure. The vehicle will require a tiers, a base standard LUN size must be chosen, and all thorough understanding as well as maintenance for a LUNs created from that base should be a multiple of smooth running machine. that base. In the example above, a 25GB base LUN size could be appropriate for all storage platforms in use. Those base LUNs could then be combined to form a Many customers move into virtualization alongside LUN of the desired size to be presented to a server. another event such as an array refresh. The majority of virtualization solutions require a host outage as the LUNs are moved from a standard array to host Another benefit of storage and data virtualization is the connection to a virtualized connection. Moving to ability to enjoy the replication capabilities the virtualized storage during a single outage that would be virtualization platform offers regardless of the underlying required anyway is a prime opportunity for most storage storage array being virtualized. Those same replication organizations. Other opportune times to move into capabilities can also be enjoyed between dissimilar
  6. 6. virtualization are during application roll outs and host Storage virtualization can be a complex undertaking. It upgrades, once again taking advantage of an outage is imperative to consider all angles when determining that is already scheduled. your storage virtualization direction. Appropriate services should be undertaken to help make this Use Case determination, taking application impact, management and training requirements, potential downtime and ROI An organization needed to solve the following business before making a technology decision. Internal issues: virtualization carries no risk or complexity, but only • Reduce application downtime due to storage solves the problems inside a single array. Network migrations based virtualization can solve problems for an entire storage environment but carries more risk and • Increase managed TBs per FTE complexity. • Reduce time and complexity required for Storage virtualization has come of age as a technology. integrations due to M&A activities It is becoming accepted, fairly widely deployed and solves many IT storage problems. We are still waiting • Reduce downtime required for re-tier requirements on some automated tools and better end to end (host to to reduce storage costs array) management visibility, but the promise and reality of storage virtualization makes taking a hard look at the benefits for your environment imperative. The enterprise’s IT organization installed HP SVSP storage virtualization solution and started a controlled roll out to selected hosts. They started with new VMware ESX hosts and virtualized existing hosts during . normal maintenance windows. Resulting benefits: • Once virtualized, a host's LUNs are able to be moved either from tier to tier inside an array or between arrays without host impact. • LUNs are able to be provisioned and replication is managed from the SVSP console, eliminating the need to use array tools. This will allow storage growth without additional FTEs • New to the environment arrays are immediately virtualized (M&A or purchase) and are then managed the same as existing arrays Conclusion Storage virtualization takes many forms and can be found at the host level, SAN fabric level and array level. Virtualization in storage arrays like HP LeftHand represents a barrier free path to utilize and make targeted arrays easier to manage, deploy and provision. However, internal array virtualization only applies to a single array thus limiting effectiveness in an entire storage environment. Storage network virtualization such as HP SVSP moves the virtualization stack outside of the array to a point between the hosts and arrays. This allows management of multiple heterogeneous arrays from a single point, making the entire storage environment easier to manage, deploy and provision. This is a welcomed feature of mobility and flexibility in today's storage industry and solves a problem faced by many IT organizations. 800-843-4488 I ©2009 Forsythe Solutions Group, Inc. All Rights Reserved. Contents may not be reproduced, in part or in whole, without prior written permission from Forsythe.