MiraLink 400 is a remote data mirroring appliance designed to be part of your business continuation and disaster-recovery plan. The product is a desktop unit that can have internal Serial ATA (SATA) or SCSI disk storage or external SCSI disk arrays that support Windows and other OS environments. You use MiraLink units in pairs. You connect one unit—a source unit—to the application server at the local site. Data written to this unit is mirrored in real time over a standard IP connection to the second unit—a destination unit—that is connected to a backup server at a remote site. Businesses commonly use MiraLink units for application data storage, either as the primary storage device or as half of a mirrored volume. MiraLink units appear to be "just a disk drive" to their respective application servers. On the primary application server, you use the Microsoft Management Console (MMC) Windows Disk Management snap-in to configure MiraLink resident volumes, just as you would configure a volume on a hard drive.
MiraLink's IntelliBuffer software insures data reliability and integrity by mirroring data from the primary server to the MiraLink source and destination units. In the event of a network failure, IntelliBuffer continues to queue the data in the source MiraLink unit. In Windows environments, data on the destination unit isn't available while the source unit is actively mirroring to it. In UNIX and Linux environments, MiraLink supports read-only access to data on the destination unit while active mirroring is in process from the source unit.
To create my test network, I used two identically configured Windows Server 2003 systems with Adaptec SCSI 29160LP Card storage controllers for my local (primary) and remote (secondary) servers. The MiraLink source unit I used for testing had 80GB of SATA disk storage and more than 75GB of IntelliBuffer storage. Physical setup consisted of connecting the MiraLink units to the local and remote server with a SCSI cable. Then I connected the servers and the MiraLink units to an Ethernet switch, as Figure 1 shows.
Configuring MiraLink units was easy. I used Microsoft Internet Explorer (IE) to connect to MiraLink's Web-based UI to assign IP addresses to the units, as Web Figure 1 shows. As recommended in the product manual, I set up and configured the units on the same network subnet.
During my testing, I used MiraLink's storage to mirror a volume and to write data to another volume; both processes worked without a hitch. My next task was to see whether I could access the data I had mirrored on the destination unit. First, I had to change the role of the MiraLink destination unit to that of a source unit—a simple matter of selecting Source on the Role tab in MiraLink's Web-based UI. Next, I booted the server that was connected to my destination unit, which was now my source unit. Finally, the Windows Disk Management snap-in showed the MiraLink source unit as a foreign disk, so I imported the disk and made its volumes accessible. The data files on both volumes were intact and usable. The MiraLink 400 worked as advertised.
PROS: Looks like a SCSI drive to the server; easy to install and configure