Building A Better SAN

Storage is a very important part of any server installation. However, given the continuing growth of customer data, even small businesses are starting to find it practical and affordable to work with a solution provider to migrate storage onto its own separate SAN.

A SAN is a common pool of storage configured to be accessible by multiple servers. SAN-based storage is typically connected via a Fibre Channel network, which requires the additional purchase of Fibre Channel host bus adapters (HBAs) and at least one Fibre Channel switch. However, for the small-business space, the use of iSCSI for SANs is growing because while iSCSI performance may not reach that of Fibre Channel in most cases, the storage can be served over a business's existing TCP/IP network. A SAN is typically built using high-availability components with hot-plug capability to prevent downtime and loss of data in the event that an error or hardware failure occurs.

SANs offer many benefits over more standard storage solutions. A SAN allows multiple storage subsystems to be handled and managed as a single pool of storage. This greatly simplifies the management of the storage pool and also makes more efficient use of all the available storage capacity. The capacity of a SAN can be increased whenever necessary, simply by adding more storage capacity to the existing drive arrays or by adding more drive arrays to the storage pool. In addition, portions of a SAN can be provisioned off as necessary to different users, departments and groups. Each user or group will see their portion as basically being their own drive.

For heavy storage users, a benefit of a Fibre Channel SAN is that storage traffic is kept off the main user network, thus making the main network more efficient for users.

In its most basic form, a Fibre Channel SAN consists of one or more storage arrays connected to one or more servers via fiber-optic cable. The array must contain Fibre Channel controllers, and the servers must contain Fibre Channel HBAs. Everything then is interconnected using one or more Fibre Channel switches.

Next: Moving Up To SAN

Moving Up To SAN

The timing for a small business to move from direct-attach storage to a SAN depends not on the number of users, but instead on how much data the company has and how it uses that data, solution providers said.

Charles Edge, a partner at 318, a Santa Monica, Calif., solution provider that partners with EMC for SAN implementations, said the need for a SAN depends on whether a customer requires high availability of data, easy expansion of capacity or performance. "The need for high availability or easy expansion is something you might see from a more mature organization, while the need for high performance is important for any company," Edge said.

Smaller businesses that already are implementing server virtualization via VMware or another application or are doing document management also are candidates for a SAN, Edge said. "In the small-business area, it's the solution driving the need for a SAN, not the technology," he said.

Craig Flint, owner of Computer ER | CERNetworks, a solution provider in Missoula, Mont., said the need for a SAN comes as smaller companies have a lot of data being created on a regular basis. "We look at what users are creating and revising, and the time it takes to go from one Gbyte of capacity to the next," he said.

Flint said most of his customers have less than 1 Tbyte of total capacity. His company is currently implementing Hewlett-Packard's All-In-One SAN appliance for two separate accounts—a photographer and an architect. "There, they have revision after revision of TIFs and AutoCAD," he said. "SANs are one of those things where it's easy to sell when the company absolutely can't expand storage fast enough."

Flint said his company has no sales staff and instead depends on monitoring a customer's servers to see if they could benefit from a SAN. "If we see a need for an additional server, we may ask them to consider a SAN," he said. "We monitor it. But if a customer doesn't need a SAN, we won't discuss it with them until it's time."

Edge said 318 is in a unique position with small-business SANs because of its location in the Los Angeles area. "L.A.'s Department of Water and Power has strung lots of dark fibre around town," he said. "We do metropolitan area networks for customers that could be a five-man editorial shop whose only customer is Universal or Disney. We can set them up with a Fibre Channel switch on each side, letting the smaller companies tie directly with the studio's SAN to collaborate on projects."

Designing a SAN can be intimidating, especially for the SMB sector, considering the typical SMB storage needs and technical expertise. A solution provider has to take into account a client's present and future storage needs, if that's even possible. The problem is in knowing how much storage a client will need in the future. One easy way around this dilemma is to start off with the minimum number of components but use hardy components that will allow easy and inexpensive capacity increases as necessary.

SAN Kits

A good head start in building a SAN can be had by using something like the HP StorageWorks 1000 Modular Smart Array Small Business SAN G2 Kit. The kit includes everything needed to put a high-performance SAN in place for not too much money. The only thing a solution provider has to decide is the number of hard drives to use and their capacity, as the kit does not include hard drives.

The heart of the StorageWorks SAN Kit is the HP StorageWorks MSA1000 Modular Smart Array, which can house up to 14 U320 SCSI hard disks and two controllers. The enterprise-class U320 drives are quite hardy, designed to operate in a 24x7 high-demand environment. They also perform well, spinning at 10,000 rpm and 15,000 rpm, depending on the model.

Furthermore, many large storage vendors, including EMC, HP, Network Appliance and QLogic, have unveiled easy-to-implement and affordable SANs that even a small-office administrator can install. For that reason, the CRN Test Center also looked at EMC's AX150 small-business SAN appliance. The AX150 can have single or dual controllers. The single-controller array can support two servers, while the dual controller can support up to four. With the controllers, the servers can be connected directly to the storage array using fiber-optic cables. To support more than four servers, the AX150 requires a Fibre Channel switch. The AX150 can connect up to 12 drives and can mix and match 250-Gbyte and 500-Gbyte hard drives to provide storage capacities ranging from 750 Gbytes to 6 Tbytes.

In preparing our step-by-step approach to SANs, the CRN Test Center consulted Brad Goubeaux, director of enterprise sales at Keep It Simple Consulting, a San Francisco-based firm that installed SAN solutions from a variety of vendors, including HP and Network Appliance.

Next: SAN Steps

Prepare Your Site
The old adage, "Look before you leap," is sage advice for solution providers about to begin installations. Before even thinking about unpacking the boxes and setting up storage, VARs need to look at and assess the customer's network and environment. The technical team should evaluate the environment against a checklist to determine what is available, what's missing and what needs to be done.

Historically, SANs used Fibre Channel. However, with faster versions of Ethernet available, solution providers now have flexibility in selecting the wiring. While Fibre Channel has traditionally been the network of choice for SANs, it is no longer as cost-effective. And it has never been as easy as Ethernet.

"In an ideal world, the SMB will use Gigabit Ethernet in the data center," Goubeaux said.

Considering most SMBs already have an Ethernet network in place, "pulling CAT 5 cables is much easier," he said. However, most SMBs will not need to consider going as high as 10 Gigabit Ethernet for their SANs.

If the customer has chosen to use Gigabit Ethernet, the VAR needs to make sure there is a Gigabit switch (major vendors include Cisco Systems, HP and Netgear) in the data center. It is not necessary to upgrade the entire network to Gigabit Ethernet, Goubeaux said.

Since HP's MSA1000 is a Fibre Channel storage array system for entry-level and midrange SANs, this Solutions That Work will touch upon the steps necessary for setting up the Fibre Channel switch as well.

Part of the assessment should focus on the SAN's physical location, such as ensuring there's enough room on the rack. If not, a new rack needs to be prepared. There also should be enough space around the chassis for easy access during installation and servicing.

The data center will need to have the proper temperature, humidity and power supply. The VAR can work with the administrators to supply the UPS and cooling system.

The final part of preparing the environment is the servers themselves. In the case of HP StorageWorks, the administration server can run Windows Server 2000/2003 or Linux. Other SAN arrays might be limited to use with a specific operating system, such as Windows Server 2003.

For a Fibre Channel SAN, as in the case of the MSA1000, the server needs to be modified to accept Fibre Channel. The HP kit includes the HBA, a PCI card that is installed inside the server. The HBA is used to connect cables from the server to the Fibre Channel switch. One or more HBAs must be installed in each server that will access the MSA1000. Simple, single-path configurations need only one HBA in each server, while redundant, multipath environments require two. HBA drivers and HBA device management applications need to be installed at this time and configured so that the HBA knows which operating system the server is running.

While basic, the solution provider has to make sure the customer has identified which of the servers in the data center will be writing to the storage. The servers that will be connected to the SAN need to be identified and their information—IP address, physical location—made available.

Next: Set up the System

Set Up the System
Now that the physical environment is ready, the fun can begin. The solution provider at this time can unpack the storage device and the switch (regardless of whether it's Gigabit Ethernet or Fibre Channel) and install them both onto the rack. The MSA1000 is a 4U box, and the accompanying 2/8q Fibre Channel switch is 2U. Once they are both fitted into the chassis and properly secured, the hard drives can be installed. Hard-drive blanks are removed to make room for each individual drive. However, HP notes that the blanks need to remain in the unused bays for proper airflow and cooling.

Once the boxes are in place, they can be connected. For a Fibre Channel SAN, cables connect the HBA to the Fibre Channel switch and also connect the switch to the array's Fibre Channel input/output module.

Once everything has been cabled together, power cables can be attached. The last step is to connect the SAN to AC power and boot the storage device, switch and UPS. Since the startup routine may take a while on the storage device, the LED indicators provide important clues as to whether the individual components are working and powered. The HP device has an LCD panel mounted on the front that also provides short status information.

Goubeaux said his team can open up the box, get the system set up and finish the cabling in less than 30 minutes. The configuration is what takes a while—anywhere from two to four hours.

Next: Configure the Software

Configure The Software
Vendors generally ship wizard-based installation CDs with their SANs to remove the guesswork and complexity from the software configuration. Solution providers use the software to configure the switch, server and the actual storage device. During the installation process, the application also will display all the devices currently connected to the SAN. This is a critical step since any servers not being seen by the storage would be identified at this time.

The application also generally has a wizard to help administrators point the appropriate servers to the actual storage. At this point, knowing the operating-system and system information that should have been already collected would make the configuration process much smoother. The basic installation will set up the storage device, verify connectivity and identify servers that will be writing to the device.

Next: Configure the Software

Finalize The Settings

The same software application generally will have more wizard-based interfaces to help configure the storage array. With a click of the mouse and a few keystrokes, administrators can create a hot spare, define pools of disk capacity and designate virtual disks. The virtual disks can be assigned to a particular server, and logical drives can be created. VARs can configure the event notification system to receive e-mail alerts.

Finally, the application also will help with the storage provisioning, the process in which storage capacity is assigned to each server. All servers do not need to be allocated an equal amount of storage space on the device—e-mail servers will need more capacity than a small test server. The allocation can be customized to the customer's needs. The hard drives need to be initialized and formatted before the servers can write to the storage.

While they are all very specific and detailed tasks, many of the major SMB SAN vendors have bundled a comprehensive interface on the software CD to make this as easy as possible.

The servers need to be made aware of the storage device. Most office administrators routinely map network drives and change passwords. This is no different from such routine tasks. Once the drives are mounted and a drive letter or path is assigned, the system is ready to go.