Accidental IT: Installing Your First SAN

Welcome to Accidental IT, a series of technical how-tos for people whose job descriptions don't necessarily include tech support but who often find themselves doing just that for their co-workers.

Your company has outgrown its disk drive capacity...again. It's time to add yet another drive to your server. Aside from the fact that your server case only has room for one more drive, there are so many things that can go wrong during the upgrade that you're dreading taking the system down. Not only are your applications and data in jeopardy, but since you need to do the upgrade outside regular business hours, you're expecting to lose the entire weekend. Maybe it's finally time to install an external set of drives on its own high-speed network. Yep, we're talking about a SAN (storage area network).

To be sure, the decision to install a SAN is not one to be taken lightly. Despite the inconvenience and pain you experience every time you add a drive to a server, the level of planning and knowledge required to properly configure and install a SAN is much more intense. In addition, the cost of a SAN is on par with the cost of a server. However, the advantages of the SAN architecture can far outweigh both the costs and implementation complexities.

SANs offer operating system independence, easy expansion, and can supply storage to multiple servers simultaneously. You can start with a few drives and add more without taking the servers or the drive system down. The design of most SAN devices allows you to choose which and how many drives are arranged in your RAID configuration, and these systems are designed for high reliability.

PlanningAll SAN devices have their own features and setup procedures. What is common among them is the need to carefully plan your setup and configuration according to how the system will be used. A part of the planning process is validating the configuration of your SAN design. Configuring a SAN is not something to do without reading and following the manufacturer's instructions to the last detail.

An advantage to SAN devices is the flexibility they offer in expansion and connections. SAN networks can grow to include multiple SAN cabinets connected to multiple SAN switches and multiple servers. For our initial installation we will assume a single SAN cabinet connected to two Windows servers. Your network may include more than two servers, and all of them can access the SAN, but the connection path is through the two fibre channel-attached servers.

An example

For this example we will walk through the setup and installation of an HP StorageWorks Modular Smart Array 1000. The MSA 1000 is a rack-mounted housing with dual power supplies, internal dual SCSI controllers, 14 hot swappable drive bays, and a fibre-channel connector. Also included in the kit are two fibre-channel adapters, an eight-port SAN switch, and cables. In other words, everything necessary to install a SAN and connect it to two servers.

HP's MSA1000 kit includes all the components necessary to set up a SAN for a small business, but you will need to purchase the drives separately.

Step #1: Plan the configuration

Determine how much drive capacity you need and purchase the drives to support the capacity and the RAID configuration needed. The drives for the MSA 1000 will typically be SCSI Ultra 320 for high performance. Other configuration factors include the server configuration, physical location, and power supplies and power sources (to support the redundant power supplies). The MSA 1000 includes a detailed yet simple configuration guide. Use whatever documentation your SAN vendor supplies, and record your configuration in detail before you start the installation process.

Step #2: Prepare the server

Update the operating system with the most current patches and updates. It is critical that the server is working properly before installing the host bus adapter (HBA) and the SAN management software.Step #3: Install the HBA

Install the fibre-channel HBA card in each of your servers. This is similar to installing a SCSI card. Be sure to use the driver supplied by the SAN manufacturer, which may be different from what is supplied by the HBA manufacturer.

Step #4: Prepare your switch or hub

Most SANs connect through a switch in much the same way an Ethernet LAN connects its components. The MSA 1000 includes an eight-port switch. Set your switch up according to the manufacturer's instructions. For this installation, one fibre-channel cable will connect the SAN array to the switch and the other two fibre-channel cables will connect the switch to the HBAs in the servers. When it's necessary to expand your SAN, you can connect more SAN arrays and more servers to the same switch based on the number of ports in the switch, and add more switches as necessary.

Step #5: Install the SAN in the rackOnce all the optional components that may require accessing the top or rear of the unit have been physically installed, mount the SAN in your equipment rack. Once the housing is mounted, install the hard drive units in the drive bays as you have previously designated during the planning phase. At the same time, mount your switch.

Step #6: Cables

Connect your power cables to the power supplies and backup units, then connect the fibre-channel cables between the SAN, switch, and computers. Follow the design layout you created during the planning phase.

Step #7: Power up the devices

The physical installation is now complete. Turn on the power to each of the units (SAN, switch, and server). Monitor the various status displays on each device according to the manufacturer's instructions. Once all the devices have successfully come online it is time to configure the SAN.Step #8: Configure the SAN

During your planning session you designated one of the servers as the management console. Install the manufacturer's configuration and management application. Use the configuration application to define the RAID configuration and partitions for the drives in the SAN according to the plan you defined during the planning phase.

Once your SAN has been configured, it is available as a storage device attached to the server or servers connected to it. Storage capacity can now be added without taking your servers off line, by simply adding drives to the SAN cabinet. Additional servers can be added to your network, and they can access the applications and data on the SAN, or can access separate partitions as necessary.