SQL Server Magazine

Imagine that you just spent thousands of dollars and numerous hours installing 50GB of additional disk space to solve your company's storage expansion problems. Then, you receive a request for more disk space. Your applications are eating up space faster than you can add it.

XIOtech's MAGNITUDE family of disk arrays helps solve your storage problems. These systems perform well and are fault-tolerant and scalable. You can use the MAGNITUDE units for additional storage even if you have local volumes on a server.

The MAGNITUDE XL-2800, which is an entry-level model, provides 288GB of data storage on up to four servers. This system holds as many as 32 Ultra SCSI II disks and includes four MAGNITUDE Host Adapter Boards (HABs), four PCI HABs for the servers, sixteen 18GB 7200rpm hard disks, and XIOtech's Remarkably Efficient Device I/O (REDI) Logical Volume Manager software. Other configurations are available, with higher-capacity disks, more server connections, and an expansion cabinet that offers 32 additional drive bays with redundant power supplies and a built-in cooling system. At press time, XIOtech was introducing 36GB 10,000rpm and 50GB 7200rpm hard disks to provide as much as 3.2TB of data storage.

Plugging In
With your order, XIOtech generally sends a representative to help you with installation. A XIOtech employee delivered the MAGNITUDE XL-2800 and familiarized me with the system, explaining all the features and ensuring that I understood them. You may not need the on-site assistance if you are familiar with data storage technologies, but the representatives provide a valuable service by showing you exactly how everything works. You can also opt for training at XIOtech's facilities, then forgo the on-site installation in favor of configuring the system yourself. The company supplies usage manuals and a technical support number in case you have problems or questions.

The system's total setup time is less than 1 hour. You can use one of two connectivity methods to set it up: the point-to-point PCI-based interconnect method or the Fibre Channel Arbitrated Loop (FC-AL) connectivity method.

The point-to-point interconnect method works with Windows NT 4.0, Novell NetWare 4.11, and NetWare 5.0. XIOtech also plans for this method to work with Windows 2000 (Win2K), but has released no specific details about compatible features other than support for Storage Manager.

The point-to-point interconnect method consists of HABs, based on Intel's i960 chip, in the server and the MAGNITUDE. You can add optional write cache in 256MB, 512MB, 768MB, and 1024MB configurations. The HAB conforms to PCI 2.1 standards, but it is not hot-pluggable at this time. A fiber-optic cable connects the HAB in the server to a HAB in the MAGNITUDE. Using the point-to-point method and fibre-channel cabling lets you connect as many as eight servers to the system via the 1Gbps full-duplex ports from as far away as 500 meters. The HABs use XIOtech's Queue Management Technology (QMT) to continuously optimize large numbers of I/O requests and remove the burden of disk I/O processing from the servers' CPUs, thus ensuring efficient use of the PCI interconnect bandwidth.

If you need to connect more than eight servers, you must use the FC-AL connectivity method. This method lets you connect a theoretically unlimited number of servers to one MAGNITUDE. Any OS that supports FC-AL is compatible with the XIOtech system. Currently, the list includes Sun Solaris, Intel Solaris, SunOS, IRIX, HP/UX, AIX, Linux, and MacOS.

Assigning virtual disks to an FC-AL loop makes the volume available to all servers in the loop. XIOtech's unique data-zoning software lets you segregate data from servers the data isn't intended for by associating a virtual disk with a specific server instead of the entire loop. You can use a point-to-point FC-AL connection to attach a server to the MAGNITUDE, but according to XIOtech, the HAB point-to-point implementation can give you higher peak performance. FC-AL is best used in an environment requiring more than eight servers. You can also use both connectivity methods concurrently.

Connecting your OS to the MAGNITUDE can be somewhat tricky. Some hardware platforms require you to make minor configuration changes in your hardware. I had some trouble with a Compaq ProLiant 2500, which required a simple jumper change on the server HAB. The XIOtech staff immediately identified the incompatibility and provided the appropriate solution. This problem occurred because of the BIOS in the server HAB. The HAB is similar to a SCSI controller and can conflict with other SCSI adapters in your system, especially if you boot from the MAGNITUDE.

You install the MAGNITUDE driver the same way you install a SCSI adapter. The server sees the new virtual disks as you add or expand the available space. After you add virtual disks to a server or expand the space in a virtual disk, you might have to reboot the server to make the space available.

In most data storage situations, you can add or remove volumes online, though your particular use of the volume might require a system restart under NT. Using NetWare, you can add and remove volumes dynamically, so a restart is not necessary. XIOtech will also support the Storage Manager functions in Win2K, so you can dynamically add and remove storage volumes without necessitating a system restart.

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