Alternatives to software mirroring
What's the best method for a total copy from drive 1 to drive 2, for the purpose of backup in case drive 1 gets corrupted? You know first-hand the downside of mirroring.
Here's our setup: Both drives are SATA-cabled. We have a Promise FastTrack 378 controller, with the drives set up in striping and independent. The computer consist of an Asus P4 3.0 Windows 2000 SP4.
This will save time and the necessity of having to load both drives from scratch. Many programs require a boot disk in DOS. Also, how is the RAID controller handled? It must a simple answer, but it's beyond my megabit brain.
This is a discussion topic that comes up from time to time but unfortunately, low-cost options are somewhat limited. The usual "ghosting" approach presents support challenges with RAID disks, making that solution unreliable in the current context. There are "bare metal restore" products available, but as the name implies, a restore or recovery operation is required. As you mention, mirroring does have its limitations, with the most obvious being the risk of corruption to two images instead of one. However, if used creatively, hardware mirroring (not software) could potentially address your requirements. Many system administrators use hardware mirroring combined with removable hard drives to that end. Once the mirror copies are synchronized on both disk drives (or sets), the drives are simply disconnected and left in the enclosure to be used if and when needed. Obviously, this approach implies the availability of removable drives but also implies fairly static data on the drives to avoid having to frequently resynchronize mirror images.
Ultimately, there are snapshot or volume replication products that allow you to create local or remote copies of disk volumes. These copies can be subsequently accessed by the system or replicated back to the original volume in case the original became corrupt. At that point however, the solution has moved far away from a simple copy of drive 1 to drive 2. As always, it then becomes a question of measuring business requirements against cost.
This was first published in March 2005