Basics of RAID

Doggie Fizzle writes "RAID has been common in business environments for ages, and is now becoming more viable and popular for personal computers. This article focuses on the the basics of RAID, and spells things out for beginners or tech veterans. From the article: 'The benefits of RAID over a single drive system far outweigh the extra consideration required during installation. Losing data once due to hard drive failure may be all that is required to convince anyone that RAID is right for them, but why wait until that happens.'"

Comments

Still a single point of failure

[L-Train8]

With RAID, you still have a single point of failure. Instead of it being your hard drive, it is now your RAID controller. So what is the advantage?

Since a RAID controller doesn't have moving parts, is it less likely than a hard drive to fail?

Windows RAID Over Firewire - Registry Setting

[meehawl]

For those who have run out of internal space in their boxes, and who don't have external SATA or expensive hardware boxes, you can run RAID over Firewire.

The problem, however, is that out of the box Windows refuses to "promote" an external disk to dynamic, which is required on all post-NT4 rigs for RAID.

The solution is to add a semi-documented Registry flag, EnableDynamicConversionFor1394 .

HOW TO: Convert an IEEE 1394 Disk Drive to a Dynamic Disk Drive in Windows XP

Couple that with a cheap 4-bay firewire JBOD box and any spare old enclosures and you are set!

I run 2TB in various RAID configs on my Windows server (main and near-line storage). Have done so since 2002. No problems with the external boxes. The support for external firewire RAID is a little gnarly in Windows 2000 - volume must be mounted as a named virtual directory and cannot be mounted as a letter drive. Later Windows give you both options.

It can be part of a backup technique...

[sczimme]

Ultimately, what it comes down to is that mirroring merely makes the hardware more reliable, it is not a backup technique.

It can be part of this nutritious breakfast^W^W backup technique:

0) shut down the box

1) swap a fresh/new/wiped drive for one of the mirrored drives

2) rebuild the RAID

3) store the just-pulled drive appropriately (e.g. off-site) along with a second identical RAID controller

Now if the machine goes completely belly-up (as in a fire) the user can install the secondary RAID controller and the data-laden drive in a fresh machine, add another fresh/new/wiped drive, and rebuild the RAID in the new machine. This may not be terribly convenient nor perfect for everyone but it will be effective.

Remember, kids: just because a particular technique doesn't perform a task all by itself (in this case RAID 1 != backup) that doesn't mean it can't be part of a larger picture.