Raid

[drew]

Having never dealt with RAID setup (knowing next to nothing on the subject, having never used in the real world):

It effectively combines all HDD capacities to virtaully show one huge volume (granted, from what I've read, certain variations apply, 8GB=4, due to mirroring)?


In the quest to build my HTPC, the mobo controller can do 0/1/0+1/5/JBOD, which, I think I know what those are (some anyway).

What is the "best" RAID setup, and/or precautions/etc to take into consideration with each.

[thesameguy]

RAID comes in a lot of different flavors, and each one has its pros and cons. In common parlance:

0 = striping, where each disk has a portion of the total data and every member is integral. Designed for speed, not security. Each disks size counts towards the whole, eg 2 1tb disks = 2tb
1 = mirroring, where each disk has a copy of the total data so one disk can totally vaporize. Designed for security, not speed - although 1 tends to have fast reads and slow writes. Every other disk is a mirror, so 2 1tb disks = 1tb
5 = distributed parity, where each member contains some of the data so one disk can totally vaporize. Designed to be cheap, so it's slow and less secure than 1. But rather than 50% of your capacity being used for redundancy, only one member of the array is, so 3 1tb disks = 2tb

There are other common RAID levels, but these are the core components... eg, RAID 10 = two RAID 5 arrays mirrored.

JBOD = just a bunch of disks, the the point here is to combined lots of physical drives into one presented volume. There is no cost, redundancy, or speed benefit, it's just for usability.

Although RAID 5 is the cheapest solution for big data sets, I would NEVER use it on anything but a dedicated controller. The recovery scenario can be VERY difficult, sometimes impossible. It's not worth the risk. If your motherboard fails, you can (likely will) completely lose access to the data on that array unless maybe you replace it with the exact same board. Dedicated controllers store their configuration in a spot on the disk and use identical algorithms, so if your Adaptec/PERC/SmartArray controller fails, you just get another similar controller and it recovers your array (usually, almost always). You frequently cannot do that with lesser controllers. Just not worth it IMHO. If you want to do RAID, go buy a cheapo PERC or SmartArray off ebay.

RAID 1 is more expensive, but safer on less hardware. Windows can handle 0,1 and JBOD natively, you don't need a controller. The advantage of letting Windows handle these tasks is broader compatibility and possibly better recovery. The disadvantage is, commonly, a 1-2% speed hit.

FWIW, my solution is I keep one copy of the data on the server (previously on the HTPC) and one copy of the data on my desktop. I use a program to periodically sync them. That way I a) don't have to fuss with RAID, and b) if something catastrophic happens in one machine my data is still safe. Likely, with the server being up 24x7 its drive will wear out and die, whereas my desktop sees far fewer hours so the drive will survive. I think it's a great way to minimize complexity, power consumption, and risk.