LynxStak 2000

Can you picture RAID devices the size of external CD-ROMs on desktops, or imagine hot-swappable power supplies and hard disks that you can access without a screwdriver? Artecon's LynxStak 2000 packages the power of RAID in a small, flexible design. LynxStak includes configurations ranging from 1 controller with 2 hard disks to 2 controllers with 14 daisy-chained hard disks. I tested a LynxStak 2000 controller with three 9GB hard disks.

Using Artecon's configuration guide, I assembled the four units. After I stacked the hard disks and placed the controller on top, I locked the parts together using the sliding bars on the sides of each unit. Artecon provides SCSI jumper blocks that replace most of the bulky SCSI cables. I connected the two lower hard disks with these blocks and connected the top hard disk and controller with a 12" SCSI cable. The controller contains two channels (connectors) that you can connect to one or two host systems. Because I was using one system, I attached one end of a SCSI cable to the controller's Host Channel 2 and the other end to my test system's Adaptec 2940UW SCSI card. Then I powered up the system.

Innovative Features
The LynxStak offers unique features in addition to the SCSI jumper blocks. For example, LynxStak lets you daisy-chain AC/DC plugs between units so that one cord provides power to the RAID controller and hard disks. Each hard disk contains a hot-swappable power supply and locking device. The product's compact design makes configuration easy.

The LynxStak controller supports multiple drive configurations, including RAID 1 plus a spare (which includes a primary drive, a mirrored drive, and the spare), RAID 3, or RAID 5 (striping with parity). LynxStak lets you configure the RAID device three ways. One way is to use the light-emitting diode (LED) display on the controller. Press the up and down arrows on the display screen until the action you want to perform appears. Then press the ENT button. Another way to configure the RAID device is to connect the controller to a VT terminal or a PC emulating a terminal using a special 9-pin serial cable (I used Windows NT's HyperTerminal program). The simplest way is to use Artecon's RAIDvisor GUI software.

Using the LED Display
After I set the SCSI ID on the back of each drive (each unit must have a unique number), I held the ENT button down for 2 seconds, let it go, and pressed it again to select the Quick Install option. I pressed the up arrow until RAID 0 appeared, then held the ENT button down again. I confirmed that my 26GB array configuration completed when I checked NT's Disk Administrator. When I used the Quick Install option, the process took 5 minutes. However, I spent more than an hour creating subsequent RAID configurations with the LED display.

Using NT's HyperTerminal
To set up HyperTerminal, I powered down the LynxStak controller and plugged one end of an Artecon cable into the front of the controller. I attached the other end to a 9-pin male-to-female gender changer and connected these to a null modem. I plugged the null modem into the COM1 port on the test computer and rebooted.

After I opened NT's HyperTerminal program, I created a new connection to COM1 and powered up the LynxStak controller. I pressed the Enter key several times, and the setup window appeared. I navigated HyperTerminal's option screens quickly and reconfigured the hard disks easily. HyperTerminal lets you easily configure and manage the RAID device because HyperTerminal provides the choices in a menu on your screen. I spent less than 5 minutes setting up HyperTerminal and approximately 15 minutes configuring the RAID device.

Using RAIDvisor
Artecon's RAIDvisor, which provides a GUI interface, lets you manage a RAID array from a host computer or remote system. The software, which comes on three 3.5" disks, is easy to install. After I opened RAIDvisor, I selected Connect from the File menu and cable RS-232 from the pop-up menu. The pop-up menu provides a list of possible connections. I chose the COM1 port and a transfer speed of 19,200Kbps. I opened the Logical Drive, Physical Drive, Host Logical Unit Number (LUN) assignment, and Volume windows and viewed them simultaneously.

Conceptually, the array setup and management process for RAIDvisor is the same as that for HyperTerminal. However, RAIDvisor is easier to understand and navigate. In addition, RAIDvisor has a more colorful interface and more manageable windows.

RAIDvisor provided an easy configuration method. After I deleted the Logical Drive (i.e., the array I configured using LynxStak's Quick Install method), I clicked the white disk symbol in the Logical Drive window and chose Create from the pop-up menu. I selected the three 9GB hard disks and the RAID 5 array. I clicked the book symbol in the Volume window and created my 26GB partition. I assigned a LUN ID to the new volume, and my array was ready to test.

I opened NT's Disk Administrator to format the new array and assign a signature. LynxStak configured the three 9GB hard disks into 18GB because the RAID 5 array uses substantial hard disk space. I copied data to the newly created disk without any problems. I installed RAIDvisor in approximately 5 minutes, and the RAID configuration completed in about 7 minutes.

Testing the Lynx's Speed
I used Iometer to test my newly created LynxStak array's I/O speed and response times. Iometer provides disk I/O subsystem measurement and characterization for simulated users (workers) operating a particular system (i.e., single or clustered). Iometer calculated the I/O per second and the average and maximum response times in milliseconds (ms) for LynxStak. (You can download Iometer for free from Intel's Web site-- http://.developer.intel.com/design/servers/devtools/iometer.)

I chose a 30-minute test with one worker generating the load. The test completed in approximately 35 minutes, and the results confirmed that the LynxStak controller and drives are blazingly fast. The I/O per second was 110, and the average and maximum response times were 9.2ms and 154.45ms, respectively. I ran the test four times, and each time the results were within 1 percent of the original results.

One Cool Cat
The LynxStak 2000 impressed everyone in the Windows NT Magazine Lab. LynxStak lacks user-friendly documentation, but the unit is flexible and lets you set up RAID configurations quickly. Hot-swappable power supplies and hard disks provide fault tolerance. The compact SCSI jumper blocks and the stackable units make LynxStak usable in any environment. The LynxStak 2000 is an innovative solution to RAID problems.

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