MAGNITUDE XL-2800

Solve your storage problems

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 peakperformance. 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.

REDI, Set, Go!
XIOtech's REDI software consists of several modules that let you perform basic and advanced functions with the volumes you create. The standard REDI Logical Volume Manager is the interface for managing RAID and virtual disk creation and manipulation.

REDI Access lets you assign one or more servers to a set of virtual disks for data zoning; this capability lets you configure servers to access data exclusively or in a shared cluster. You can also prioritize individual connections for optimal performance where you need it most.

REDI Copy lets you create mirrored copies of virtual disks. You can mirror a virtual disk and perform a backup without taking the server down or affecting data access. Copying virtual disks lets you perform tests with confidence (e.g., Year 2000—Y2K—tests, software development environment tests). With mirrored copies, you always have a backup copy of your server volumes.

REDI Control adds remote configuration and monitoring capabilities to your system. You can keep tabs on your system's performance, rearrange or add volumes, and mirror volumes. This component uses TCP/IP for communication over your Ethernet network. The MAGNITUDE console has a network stack that loads automatically, a feature that enables SNMP management using any standard SNMP manager, such as HP OpenView.

Flexing the Muscle
XIOtech designed the MAGNITUDE from a systems administrator's perspective. The system lets you manage disk space rather than disks. Thus, adding, moving, and changing RAID and volume configurations is easier than ever before. The underlying disks are independent of the RAID volumes and virtual disks you create. When you create these volumes, you specify their size without regard for which physical disks you'll use. The MAGNITUDE manages how the data is laid out on disk, so you don't have to worry about how to optimize data layout for the best performance.

When you create a RAID volume, you specify its size, its RAID level (i.e., 0, 1, 5, or 10), and which disks will store the data. You can configure volumes to use only a specific set of disks. For instance, if you have a standard 288GB disk configuration (sixteen 18GB 7200rpm disks) and sixteen 36GB 10,000rpm disks installed, you can create two drive sets to represent the two disk types. For demanding applications, you can specify that the RAID volume be on the faster set of disks. As you see in Screen 1, when you create a drive set, you can view the drive locations so that you know which disks the drive set includes. Any or all of the eight available drive sets can include a particular disk.

In addition to the eight definable drive sets, the MAGNITUDE has a default drive set called All Data Drives. This drive set consists of all the physical disks that can contain data. You configure the disks as unused, reserved as hot spares, or available for data storage. When you use the All Data Drives set to create a RAID volume, data is striped over all the designated data disks that have available space. The physical disks can be of varying types, speeds, and capacities; the MAGNITUDE includes space from all designated disks regardless of their specifications.

You'll want to use as many disks as possible in your RAID volumes, because the more physical disks a volume includes, the better it performs. The MAGNITUDE automatically manages all the data striping, parity information, and hot sparing. You can take some control by changing the number of parity drives or performing a Copy/Swap to a newly created RAID with complete transparency. The new RAID can have a different configuration from the original one. For instance, if you have a RAID 5 array and wish to copy its information to a RAID 10 array, you can do so—without interruption and while the server is running.

Free Association
After you define your drive sets and create and initialize your RAID volumes, you need to create virtual disks to associate with your server connections. These virtual disks can be any size, up to the maximum size of the RAID volume. You number them from 0 to 31 (you can have as many as 32 virtual disks per server). After you create virtual disks and assign them to servers, the OS can partition the disks and format them with any OS-supported file system.

To assign virtual disks to servers, you associate them with the MAGNITUDE's eight clusters. Then, you assign server HAB connections to the clusters. Figure 1 depicts the MAGNITUDE architecture, in which you assign servers to logical device hubs (i.e., clusters). In the figure, Server 1 is assigned to Logical Device Hub 1 (i.e., Cluster 1), as are two virtual disks—a 50GB disk and a 30GB disk. As you can see, these virtual disks are independent of the physical disks. The virtual disks can belong to the same RAID 5 array or different RAID arrays (e.g., RAID 5, RAID 10) that are striped across the same set of disks.

Figure 1 illustrates the MAGNITUDE's support for redundant server connections, server clustering, and high-performance multi-HAB connections. For example, Server 2, which is a Hot Spare/Backup, isn't assigned to a logical device hub. If Server 1 experienced a hardware failure, you could assign Server 2 to Logical Device Hub 1 for booting. Thus, the server could be up and running within minutes of experiencing a system hardware failure.

Watching from the Sidelines
The MAGNITUDE's console runs on a Pentium PC inside the system's storage cabinet. This PC is active only during the system's startup, configuration, and monitoring sessions. After the system boots, you can turn off the PC. This structure is cost-effective because XIOtech doesn't need to build redundancy into the PC.

The system's console has several performance-monitoring capabilities that let you determine how your system is performing, including the performance of individual disks, virtual disks, or RAID arrays. A drawback is that you can't capture data over time for long-term analysis.

Screen 2 shows some of the information available for monitoring the system, such as physical drive statistics. At the bottom of the console is a readout of the system's I/O in megabytes per second. You can also view each HAB's status, the processor's status, the communication link, and the environment or temperature. At the very bottom of the display is a small window that shows the most recent system events. The MAGNITUDE stores all events and status information in a system log that you can review later.

Benefits
The MAGNITUDE makes your job easier. One advantage is that you can add space on the fly to give users the storage space they need without rebuilding or restriping data on servers.

The system's virtual disks give you additional flexibility. Suppose you need higher redundancy and better performance on a volume. The MAGNITUDE lets you easily create a RAID 10 array to replace your existing RAID 5 array. Then, you need to create virtual disks of equal or greater size for all the virtual disks you want to migrate. Finally, you must tag a virtual disk for Move/Copy and perform a Copy/Swap operation. This action mirrors the original virtual disk to the new virtual disk as the server continues to run. When the mirror process completes, the MAGNITUDE takes the old virtual disk offline and leaves the new RAID 10 virtual disk running. Any write operations that you perform during this transition occur on both RAID arrays. The swap occurs only after the arrays are identical.

You can also move or copy a virtual disk to another cluster. This method is useful in setting up testing and development environments or configuring a dedicated backup server. Moving a server's volume to another server is as simple as moving the virtual disk. Again, in some situations, a system restart might be necessary, but this step isn't necessary in typical data storage setups.

After the Sale
XIOtech's customer service and technical support are outstanding. During my testing process, I experienced a disk failure. I had identified a hot spare, so the system continued to run uninterrupted. Still, I called XIOtech's technical support department and received a new disk drive the next day.

Within a week, I received a phone call from XIOtech. The company had sent the faulty drive to Seagate for analysis and wanted to let me know that the problem I experienced originated with Seagate.

XIOtech includes a 1-year, onsite, next-day warranty with all systems to take care of any problems you might have. Additionally, the product comes with a standard 3-year parts warranty, which ensures that the company will promptly replace any problematic components.

To minimize your downtime in case of a system board or processor failure, XIOtech offers a spare-parts kit that includes a processor, a HAB, a 20-meter fibre cable, and several smaller components. This stock kit covers the nonredundant processor and HAB connections, which a systems administrator can replace easily using only a screwdriver. You can also hot-replace all the redundant components, and you can create a custom spare-parts kit to include such items as power supplies, fans, blowers, and drives.

Bottom Line
The MAGNITUDE is the most flexible piece of data storage equipment I've worked with. Without even using the system's full capabilities, I was able to reduce a database consistency check's elapsed time by 50 percent simply by moving a seven-disk RAID 5 array from an existing high-performance server platform to a seven-disk RAID 5 array in the MAGNITUDE. The system offers diverse configurations that you can use to customize your environment.