Finally, affordable SANs.

During times when infrastructure spending is flat or reduced, storage management is at the center of increasingly complex IT problem. Today, most of the storage deployed in small and large businesses is directly connected to individual server groups. Direct-Attached Storage (DAS) is expensive and does not scale easily. DAS is also inefficient because it cannot be shared among servers, resulting in low utilization. All the while, applications continually demand more from their storage systems, putting increasing pressure on servers and storage products as their capacity, availability, backup, and disaster recovery needs intensify.

Storage consolidation using Storage Area Networks (SANs) does provide a solution; however, there are significant barriers to deploying SANs in many environments Conventional Fibre Channel SANs are expensive because they are built from relatively low-volume components and cannot be managed in an integrated manner. To attract the mid-range storage market and provide a solution for business critical applications, a consolidated storage solution must deliver the features of today's SANs ae but at a significantly lower cost and with less management overhead.

Fortunately, the advent of Ethernet-based SANs and the iSCSI standard means that it is possible to combine the simplicity of Ethernet networks with the advanced storage features mandated by mission-critical applications into a reasonably priced and easy-to-manage product.

Storage Consolidation

Storage consolidation ae a single, large, shared pool of storage that can be accessed by a variety of heterogeneous servers and applications on a network ae is an architecture that allows storage devices and servers to be acquired, managed, and upgraded independently. Centralized storage management can result in lower management costs, high availability, easy scalability, and efficient storage space utilization, in addition to simplified backup and disaster recovery strategies. With consolidated storage, costs can be shared by the various departments and entities utilizing the storage. One method of consolidating storage is to set up a SAN.

A survey of 86 companies, conducted by Robert W. Baird, shows the typical reasons customers install a SAN (see Figure 1).

[FIGURE 1 OMITTED]

Barriers to Using SANs for Storage Consolidation

What prevents the widespread use of today's SANs in the data center is the cost and complexity of deployment and maintenance. To implement an overall solution, many individual hardware and software components must be installed and managed in a synchronized fashion. The burden of supporting and upgrading many disparate elements is intimidating to organizations without large staffs and budgets. Often, the hardware and software do not operate in an integrated manner. Implementers address the problem with customized management solutions, which add to the burgeoning problem of heterogeneous or non-standard storage management. Often, SAN configuration complexities require that IT managers learn new tools and technologies in order to manage the various hardware platforms and the multitude of management interfaces created as a remedy for ongoing storage management problems.

These costs and complexities are acceptable in a mission-critical application environment, which is where Fibre Channel SANs have been beneficial. However, the typical environment for business-critical applications generally does not have a system management budget that can handle these concerns. It is not unusual for storage management to be part-time job for one or more people. Simply stated, a SAN cannot be used as a consolidated storage solution for mid-range storage unless it can deliver high-end features at significantly lower cost and with less complexity than the offerings available today. In addition, storage configuration must be simplified and day-to-day management tasks minimized, while avoiding the use of specialized networking technology that requires extensive training.

The survey previously referenced also reveals that 62% s of respondents cited high initial deployment costs as a main impediment to the deployment of SANs for mid-tier servers. One Fortune 500 manager said, "Our large, redundant, expensive SAN is overkill for this class of server and is, therefor, not a cost-effective solution."

Consolidated Storage for Business-Critical Applications

Today, there is a growing need to provide a consolidated storage solution for business critical applications with the same functionality as solutions geared toward mission critical applications ae but at a significantly lower cost and without excessive administrative overhead. This represents a business opportunity for an affordable, mid-range storage solution that protects data and also delivers advanced storage management features, such as seamless expandability, automatic load balancing, disaster tolerance, and replication. Such a solution would enable businesses to move away from DAS and enjoy the benefits of consolidated storage without the cost and complexity of conventional high-end storage products.

Affordable SAN Case In Point

An important example of affordable SAN is the PeerStorage Array 100E from a EqualLogic, the foundation of PeerStorage Solutions. This product delivers high-end storage management features in a affordable Ethernet-based SAN.

Modular design means you buy only the storage that is essential today ae when more space is needed, capacity can be seamlessly expanded while data remains online. With integrated storage management features such as automatic RAID configuration and load balancing, snapshots for centralized online backups, and remote data mirroring for disaster tolerance, the PeerStorage Array 100E can decrease the cost of deploying and managing storage.

The Array is a self-contained, fault-tolerant iSCSI block storage array designed for Ethernet environments. Each array contains industry-standard disk drives, high-performance storage controllers, and redundant, hot-swappable hardware, including power and cooling components, in a rack-mountable chassis. Connecting an array to a network and running a simple utility are the only requirements for installation. Total setup time is less than 20 minutes.

Configuring one or more arrays into a group allows you to manage multiple arrays as easily as you can manage one. A group presents a single, dynamic pool of shared storage. Administrators allocate portions of the storage pool to volumes, which are seen on the network as iSCSI targets. As arrays are added to the group, capacity and network bandwidth expand seamlessly ae with no user intervention required and no increase in management overhead. Data placement and load balancing across disks and arrays occur automatically, as needed. Figure 2 shows a PeerStorage Group with one PeerStorage Array 100E.

[FIGURE 2 OMITTED]

Specifically, group provides the following benefits:

Runs on ordinary Ethernet networks with the iSCSI protocol. By using standards-based technologies, there is no need to train administrators in specialized technologies and hardware, such as Fibre Channel. Interoperability issues, common in many SANs, are not a problem.

Reduces costs due to the high volumes and intense vendor competition in the Ethernet hardware market. One of the major costs when building a FC SAN is the cost of connecting a server, which ranges from $2450 to $4000 per connection. This alone makes Fibre Channel an impractical technology for mid-range servers. Using standard Ethernet technology, the cost of connecting a server is in the range of $80 to $850 per connection.

Uses iSCSI to provide robust authentication between the providers and the consumers of storage resources. This eliminates the need to understand and manage arcane security features, such as Fibre Channel's Switch Zoning and LUN Masking.

Delivers enterprise-level functionality as part of the base product. Included are multi-path access, graphical and command line management interfaces, volume snapshots, host access controls, automatic load balancing, and synchronous remote data mirroring. There are no software licenses to deal with, and maintenance is greatly simplified. One does not need multiple management consoles to perform a storage management procedure on behalf of an application. Volume creation, resizing, and backup/restore operations using snapshots can all be done in a single Web browser session.

Eliminates the need for administrators to manually map volumes onto physical disks or individual controllers. To create a volume, you specify only a name and size. To increase the size of a volume, specify only the new size. The group handles the details of storage allocation and capacity balancing across the available physical disks and arrays. In addition, dynamic rebalancing occurs automatically as performance metrics change.

Automatically reallocates physical resources to volumes when the hardware configuration changes. This means that when an array is added to a group, the additional storage space, disk performance, and network bandwidth provided by the new array are immediately available to applications ae with no manual configuration tasks required.

The Cost-Effective SAN

With the introduction of the PeerStorage Array 100E from EqualLogic and products like it, it is now possible to move from a DAS environment to a consolidated storage solution that offers the benefits of networked storage at a significantly reduced cost and without the complexity of Fibre Channel SANs.

It is possible to demonstrate the cost benefits of a group, as compared to equivalent DAS and SAN solutions. The initial storage costs for hardware, software, and training, in addition to the ongoing management and maintenance costs for hardware and software were compared for DAS, FC SAN, and group configurations. Two environments were used: a five-server, 2TB storage environment (raw capacity) and a twelve-server, 5TB storage environment. The hardware, software, training, and maintenance costs for the DAS and FC SAN configurations were obtained from distributor websites such as cdw.com. They are "street" prices, not list prices.

DAS storage solutions are generally assumed, utilization issues aside, to have the lowest initial purchase cost. And, when application storage needs are modest enough that the needed disks can be fit into the server enclosure, this is true. But when application storage needs exceed the limited space in the server enclosure, external storage enclosures are needed. The cost of per-server external storage enclosures ae each with its own power, cooling, and electronics ae- drives the hardware cost of DAS above that of a SAN solution.

Fibre Channel SAN solutions squander their cost advantage over DAS because of their high connection costs (switches and HBAs) and the additional SAN management and multi-path access software they require. As can be seen in Figure 4, these costs drive the total acquisition cost of FC SAN considerably above that of DAS. A group, on the other hand, requires no extra software and uses commodity Ethernet products for connectivity, so it is cheaper than DAS in all dimensions ae hardware, software, connectivity, training, maintenance, and ongoing management costs.

[FIGURE 4 OMITTED]

Ongoing system management costs are the most difficult data to obtain. Thus, an analytical approach was taken to determine these costs. First, a set of activities was identified. These activities are representative of the tasks a storage administrator performs on a regular basis and include creating and resizing volumes, installing new disks or new storage units, and analyzing and rebalancing the storage load. Then, several administrators were interviewed to obtain estimates of how long these activities take and how often they are performed. This input provided a basis for determining the relative effort required to manage the DAS, FC SAN, and PeerStorage Group configurations.

Industry literature was also examined to determine the largest physical storage configuration the average administrator could handle. The industry estimates varied from 800GB/person to 2.6TB/person for DAS, and from 6TB/person to 24TB/person for a FC SAN ae a wide range.

The dollars-per-terabyte costs shown in Table 1 were obtained from an understanding of the comparative complexity of the DAS, FC SAN, and PeerStorage Group configurations and their required hardware and software components the information gleaned from administrators, and the relative efforts required for the common activities. Ultimately, the costs were lower than the industry range for DAS, and in the high end of the industry range for FC SAN and PeerStorage Groups, possibly reflecting the fact that the industry literature presented an overly optimistic attitude towards SANs in general. The costs from Table 1 were then used to establish the ongoing yearly costs for each configuration, as shown in Tables 2 and 3.

As Tables 2 and 3 show, not only does a PeerStorage Group have a lower management cost than a DAS or FC SAN solution, it also has lower initial costs. For a manager of mid-tier storage who is currently using DAS but is looking for a consolidated storage solution, the choice is clear. Instead of an expensive, complex, conventional SAN solution, Ethernet-based PeerStorage Solutions from EqualLogic provide the most effective use of corporate funds. The total three-year cost of a PeerStorage Group is 45% of the cost of today's SAN solutions, and a mere 35% of the cost of DAS solutions.

Conclusion

In summary, arrays like EqualLogic's PeerStorage Array 100E deliver a self-managing storage array that provides enterprise-class features using industry-standard Ethernet SAN connectivity and the iSCSI standard protocol. The result is an ideal consolidated storage solution for midtier storage in the data center.

This demonstrates an affordable consolidated storage solution. Over three years, the cost of a PeerStorage Group is 35% of an equivalent DAS configuration and approximately 45% of an equivalent SAN solution. Strategies like these eliminate the barriers to adopting consolidated storage and deliver a simple solution that provides an excellent return on investment.

Table 1--Management Costs/TB assuming burdened manager salary of $75K

                    TB/Person   Persons/TB    $/TB

DAS                     3         0.333      $25,000.00
FC SAN                  8         0.125      $ 9,375.00
PeerStorage Group      16         0.0625     $ 4,687.50

Table 2--Comparative costs for 278 solutions

                                  PeerStorage   DAS          FC SAN
                                    Group
Hardware and Software Purchases   $ 42,805      $  59,022   $  81,849
Installation and Training         $  1,563      $  10,805   $  20,380
3 Years of Hardware Maintenance   $ 11,557      $  11,430   $  14,797
             Total Initial Cost   $ 55,925      $  81,257   $ 117,026
Yearly Software Support Cost      $      0      $   2,529   $   4,368
Yearly Management Cost            $  9,375      $  50,000   $  18,750
            Total Initial Cost    $  9,375      $  52,529   $  23,118
             Total 3-Year Cost    $ 84,050      $ 238,843   $ 186,381

Table 3--Comparative costs Of 518 solutions

                                  PeerStorage      DAS       FC SAN
                                     Group
Hardware and Software Purchases   $ 101,293     $ 106,629   $ 219,807
Installation and Training         $   1,875     $  17,129   $  25,775
3 Years of Hardware Maintenance   $  27,349     $  28,919   $  36,340
             Total Initial Cost   $ 130,517     $ 185,736   $ 281,922
Yearly Software Support Cost      $      0      $   5,951   $  10,045
Yearly Management Cost            $  23,438     $ 125,000   $  46,875
             Total Initial Cost   $  23,438     $ 130,951   $  56,920
              Total 3-Year Cost   $ 200,829     $ 578,587   $ 452,683

Figure 1--Customer reasons for buying SANs

Percentage of Respondents

                          Backup   11
                   Manageability   12
         Availability/Redundancy   12
                     Reliability   18
                     Performance   25
Scalability and Resource Sharing   62

This feature was provided courtesy of EqualLogic.

www.equallogic.com

Ellen and Richard Lary, nationally known technologists in mass storage, are principals at Tutelary LLC.